Microbial Enhanced Oil Recovery Pilot Test in Piedras Coloradas Field, Argentina by NED SPE STUDENT CHAPTER

SPE 53715 Microbial Enhanced Oil Recovery Pilot Test in Piedras Coloradas Field, Argentina M. A. Maure, SPE, and F. L. Dietrich, SPE, Microbes, Inc. and V. A. Diaz and H. Argañaraz, Perez Companc S.A.

Copyright 1999, Society of Petroleum Engineers Inc. This paper was prepared for presentation at the 1999 SPE Latin American and Caribbean Petroleum Engineering Conference held in Caracas, Venezuela, 21–23 April 1999. This paper was selected for presentation by an SPE Program Committee following review of information contained in an abstract submitted by the author(s). Contents of the paper, as presented, have not been reviewed by the Society of Petroleum Engineers and are subject to correction by the author(s). The material, as presented, does not necessarily reflect any position of the Society of Petroleum Engineers, its officers, or members. Papers presented at SPE meetings are subject to publication review by Editorial Committees of the Society of Petroleum Engineers. Electronic reproduction, distribution, or storage of any part of this paper for commercial purposes without the written consent of the Society of Petroleum Engineers is prohibited. Permission to reproduce in print is restricted to an abstract of not more than 300 words; illustrations may not be copied. The abstract must contain conspicuous acknowledgment of where and by whom the paper was presented. Write Librarian, SPE, P.O. Box 833836, Richardson, TX 75083-3836, U.S.A., fax 01-972-952-9435.

Abstract Extensive feasibility tests involving Microbial Improvement Technology were conducted with the two main productive formations in Piedras Coloradas Oilfield, Mendoza Province, Argentina. The program started March 1997 and continued during twelve non-consecutive months. Six producer wells, two of them horizontals, were under a systematic program of inoculations using hydrocarbon-degrading anaerobicfacultative microorganisms. A complete set of rheology parameters, specific geochemical fingerprints and biomarkers comparison was used to evaluate pre- and post-trial compositional alterations in produced fluids. Project performance in terms of fractional flow evolution was correlated with well completion configuration and reservoir petrophysics by the use of parametric models and compared on a well-by-well basis with corresponding decline and complementary baselines. Incremental Oil averages 66% over baseline with minimum values of 28.5% and maximum above 110%. Results are consistent and show a clear correlation between treatment design modifications and water cut reduction. This correlation proves that Microbial Enhanced Oil Recovery methods are controllable and predictable if team integration and proper engineering methods are observed during pilot design and well monitoring stages. Cost per Incremental Barrel (CIB) was 5.1 $/barrel during pilot stage. On MEOR Expanded scales, this value is forecast to decrease to below 2 $/barrel. The project demonstrates that this technology is cost effective, easy to implement and complies very well with local environmental regulations and biosafety issues. This pilot program is the first part of an integral mid-term strategy to use biotechnology in paraffinic oil bearing

reservoirs. Further evaluations in course will be covering microbial influence mechanisms on waterflooding methods. Introduction Enhanced Oil Recovery pilot tests using biotechnology methods were conducted with the two main productive formations in Piedras Coloradas Oilfield,Mendoza Province, Argentina (Figure 1). The objective of these trials was to determine project performance in terms of fractional flow evolution and its correlation with well completion configuration and reservoir petrophysic parameters. By the use of experimental design techniques, associated objectives were achieved to determinate how predictable and controllable this technology is based on previous screening criteria and monitoring routines. Piedras Coloradas Field Description The field was discovered in 1953 and production started in 1956. It is located in Argentine Republic (South America), 65 km southwest of the city of Mendoza. It is part of NW-SEoriented trend of oilfields that parallels the western margin of the Cuyo basin. The field produces from two separate reservoirs: Conglomerado Rojo Inferior, named C.R.I.(Barrancas Fm.) and Victor Oscuro Member (Rio Blanco Fm.). The first accounts for 80% of the total production (Figure 2). The area produces 430 M3/D of very paraffinic oil becoming from 85 active wells. Average production per well is 5.8 M3/D with a standard deviation of ±7.3 M3/D). Active wells are grouped in four batteries and 24 of these are horizontal. Eighty percent of Piedras Coloradas production comes from 38% of wells. The field has incipient waterflooding projects with 6 wells injecting 1100 M3/D in both reservoirs. MEOR: Conceptual frame Microbial Enhanced Oil Recovery (MEOR) technology is based on the systematic inoculation of producing wells with hydrocarbon-degrading anaerobic-facultative microorganisms. The primary goal of the method is to extensively colonize the poral medium of the oil bearing . [Ref .: 1, 16] Seven different microbial products (sub-communities) of highly motile, synergetic, symbiotic microorganism consortia were initially used to test Piedras Coloradas oil biotreatability. These strains are naturally occurring bacteria capable of deriving nourishment from linear hydrocarbons. A combination of products is necessary to adjust the bacterial

M. A MAURE, F. L. DIETRICH, V. A. DIAZ, H. ARGAÑARAZ

community to specific substrates (oils) and reservoir conditions. Microbial products are also conditioned to have an adequate balance in type of complementary nutrients, buffers, trace elements (K+, Na+, Mg++, Ca++, Fe++/+++, Zn++, Co++) and bio-catalizers, since formation water usually lacks sufficient nitrogen and phosphorous. Secondary objectives of this stage are to stabilize enzymatic reactions at water/oil interfaces in the productive formation, in order that such biochemical action can modify oil mobility, by the generation of solvents and bio-surfactants. Differences in microbial effect in treated wells could be detected in two consecutive stages: 1- Clean-up effects by the removal of organic damage occurring in the near wellbore of the perforated interval, opening non-productive zones bearing oils with a more segregated, heavy and pseudoplastic behavior. This effect produces a high peak in oil rate but only for a limited time (Figures 19, 20 and 21). 2- Rheological effects by the compositional alteration occurring at deeper colonization radius, in drainage zones with extremely low shear rate values. This effect is the most important MEOR objective to pursue in treated wells, as this improvement is sustainable for a long period if proper microbial inoculation schedule is continued (Figure 23, c2 segment, Figure24, v-w segment). The proof of these alterations and consequent modifications is accomplished by serial Rheological Lab Procedures (Annex A) in combination with Organic Geochemistry Methods (Biomarkers and GC-MS Chromatography, Annex C). The change in amount and compositional characteristic of produced fluids arises as a consequence of microbial action on saturated hydrocarbon substrates under anaerobic conditions accompanied by a strong modification on N/P ratio in the colonized poral volume. Changes in micro-environmental parameters existing in poral space promote specific metabolic paths that ultimately produce the cracking on linear and branched paraffin compounds, which are present in abundance in Piedras Coloradas oil (Figures 31, 32). The expected result is the shifting in molecular weight and chain length toward a lower range and greater compositional homogeneity. The most significant evidence is the viscosity reduction at low shear rates and the shift in pour and cloud temperature points (Figures 42 and 43, Annex A). Candidate wells were selected as producers from only one reservoir (Barrancas or Rio Blanco), avoiding treatment of multilayer systems, with different petrophysical parameters. Related Case: Tupungato MEOR Project Tupungato is a neighbor field in close connection with Piedras Coloradas area. The North-West limit is common for both areas. It is also part of NW-SE oriented trend of oilfields that parallels the western margin of the Cuyo basin. In July 1994 a MEOR pilot project was started and conducted for two years, involving the same formations and showing very positive results. Project details were discussed in a previous technical

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paper [Ref.: 1], and served as an important reference to encourage MEOR application in Piedras Coloradas field. MEOR In Piedras Coloradas Field General Screening Criteria Primary requirements to check are: 1. Crude oil composition must contain n-alkanes in sufficient amount and show little or no evidence of previous levels of biodegradation by indigenous microbiota. Table 6. 2. Bottom hole temperature need to be less than 250 °F. Pressure is not a limiting factor. 3. Chlorides less than 100,000 ppm in the formation water. 4. PH is best near neutral. 5. Pore throat distribution in objective reservoirs needs to have a minimal portion above the range of microbial community size to permit microorganism migration. This requirement means to have an "available window" in poral geometry to permit profound microbial incursion (Figures 3, 4, 5 and 6). Fluid Evaluation, Oil Comparison of a complete set of rheology parameters, specific geochemical data, ionic patterns, fingerprints and biomarkers was used to evaluate pre- and post-trial compositional alterations in produced fluids. PVT relevant data. Bubble pressure (psi): GOR (M3/M3): Bo factor (M3/M3 ): Viscosity (cp, SR>20 s-1, 180°F): API°:

1023 37 1.176 4.5 (Roll Ball viscometer) 32 (Reservoir condition)

Geochemical background In October 1988, Geochemical Analyses were performed on five oils from Piedras Coloradas field (EI-14, PC-29, PC-44, PC-55 and PC-74). This report provide a clear evidence that these oils could be good targets for a MEOR program, in close agreement with results obtained in Tupungato pilot project. Main conclusions were [Ref.: 2]: • All five Piedras Coloradas oils belong to one oil family. • All are very paraffinic, undegraded oils that were sourced from a single source facies. • All geochemical parameters indicate a single oil type, with normal alkane distributions. • Pristane/Phytane ratios and carbon isotope ratios are particularly diagnostic oil-oil correlation parameters. • The oils show no signs of water washing or biodegradation. • An odd-carbon preference is discernable in the oils, both in the medium range (C17, C19) and higher molecular weight (C23, C25) n-alkanes. These preferences, together with the presence of C27 and C29 steranes suggest the oils were derived from both algal and terrestrial precursors (Table 6).

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MICROBIAL ENHANCED OIL RECOVERY PILOT TEST IN PIEDRAS COLORADAS FIELD, ARGENTINA

MEOR-oriented geochemical studies Two independent geochemical laboratories and consultants were selected to evaluate compositional alterations and their correlation with rheology parameter evolution. Conceptual basis and methodology. Changes in the composition of petroleum during a MEOR process can be followed through analyses that are typically applied in the geochemical characterization of rock bitumens and oils. These changes could occur at a bulk or molecular level, most likely both, and are difficult to anticipate: each oil type subjected to a specific microbial batch treatment reacts in a different manner under particular subsurface conditions. Moreover, these changes are time-dependant and several of them sequential, and could show up at very different times in non-related oils. A summary list of the analytical techniques applied to the geochemical characterization of oils can be found in Annex C. Short comments of the changes that could be expected after a MEOR process on a particular oil are: • Liquid Column Chromatography is applied after precipitation of asphaltenes to determine the proportions of saturated hydrocarbons, aromatic hydrocarbons and resins + NSO (nitrogen, sulfur, oxygen) compounds. The naphthenes can be later estimated as a part of the saturates from the whole oil gas chromatography. These five fractions are expected to change after a MEOR process. Modification of API gravity should be related to the changes in the bulk composition of the oil. • Percent Sulfur is a typical bulk parameter of an oil, which will likely be modified after a MEOR process. • High Resolution Whole Oil Gas Chromatography typically allows determination of normal- and isoparaffins (quantitatively, in ppm) and defines the “envelope” of an oil. Ratios between compounds and relations between ranges of compounds (light, medium, heavy) as well as the chromatogram baseline should change after a MEOR process. • Gas Chromatography of the Saturated Hydrocarbon Fraction basically provides the same information as whole oil gas chromatography but is more precise in resolving peak co-elution and allows better ratio calculations. However, a big disadvantage is that during isolation of the fraction the light compounds <C15 are partially or totally lost. • Gas Chromatography of the Aromatic Hydrocarbon Fraction allows identification and quantification of the typical aromatic compounds present in oils: methyl-naphthalenes, dimethylnaphthalenes, trimethyl-naphthalenes, phenanthrene, methyl-phenanthrenes and dimethyl-phenanthrenes. Relationships between these groups of compounds and between isomers could change after a MEOR process. • Detailed C6-C7 Gas Chromatography. Twenty-five compounds are identified and quantified in the C6-C7 range through gas chromatography. The range is very

•

sensitive to microbial attack and should experience changes after a MEOR process. Stable Carbon Isotopes of Whole Oil, Saturates Hydrocarbon Fraction And Aromatic Hydrocarbon Fraction. The δ 13C values are bulk characteristics of oils. After a MEOR process the values could hypothetically show minor to significant modifications. Gas Chromatography – Mass Spectrometry Of Saturates Hydrocarbons. The terpane and sterane biomarker fingerprints represent extraordinary valuable information in the characterization of an oil (source, thermal maturity, biodegradation). A MEOR process could very possibly modify molecular ratios and parameters of these fingerprints. Gas Chromatography – Mass Spectrometry Of Aromatic Hydrocarbons. Similar to saturate biomarkers, the fingerprints of aromatic steranes are a supplement to the molecular characterization of an oil. In addition, the method allows quantification of 2- & 3-ring aromatic hydrocarbons (naphthalene, phenanthrene and dibenzothiophenes compounds).

Rheological studies Conceptual basis. Oil as very complex substance exhibits typical non-Newtonian behavior. Viscosity is shear rate sensitive (pseudoplastic model) and it correlates strongly with the fluid dynamics occurring in the poral space. The concept of constant viscosity in the drainage area is no longer valid, rather "apparent" values are pertinent. Specific quantitative lab procedures were conducted to measure the shift in rheological properties in treated (inoculated) and untreated (control) samples obtained from well head manifold for every candidate well. Lab indexes and methodology. Serial assays were conducted to determine the alterability of Barrancas and Rio Blanco oils under systematic microbial influence (enzymatic cracking). Basically, lab procedures consisted of serial inoculations of oil with seven different microbial products, followed with 48 to 96 hours of controlled atmosphere incubation at specific temperatures. Further examination of inoculated and control oil (originals) using full computational rotational viscometers (Brookfield DVII+/III models), will be produced the necessary plots and data vectors to generate quantitative indexes. Deviations in µapp.[mpa.s] vs. Temperature [°F] and µapp.[mpa.s] vs. Shear Rate [1/s] curves were the basis for calculating quantitative numbers describing the degree of compositional alteration. Mathematical expressions for these dimensionless indexes are described in Annex A. These numbers translate the graphical information into lab performance indicators. Furthermore, they are used during pilot monitoring to contrast and compare lab and field figures. So, the Newtonian Index (NI) is used to evaluate the shifting from shear rate sensitive (pseudoplastic) behavior toward a more newtonian fluid. The comparison between

M. A MAURE, F. L. DIETRICH, V. A. DIAZ, H. ARGAÑARAZ

control and inoculated oil samples is evidence of microbial cracking by each different microbial culture. To test as positive NI need to be greater than 1.10. (Eq.32) The Delta Viscosity (DV) Index measures the global change in apparent viscosity in the explored range of shear rates (minSR, maxSR). To test as positive DV need to be greater than 0.10, (Eq.33) By direct mathematical manipulation of DV index, a simple version of Enhanced Oil Recovery factor (EOR Index) is obtained, as related only to viscosity contribution. An exceeding EOR value from 1.15 tests as positive, (Eq. 34) A data base of 84 oil samples from 11 different fields (22 from P.C. area), pertaining to the same sector of Cuyo sedimentary basin were tested to define general rheological properties of Mendoza North oils. First evaluations start on 1994. In general all these crude oils tested far above cut-off values, evidencing very good microbial treatability. Piedras Coloradas values in pre-selected wells were: Sample

EOR

PC-1020 (Horizontal, V.O.) PC-1022 (Horizontal, V.O.) PC-86 (Vertical, V.O.) PC-94 (Vertical, V.O.) PC-19 (Vertical, C.R.I.) PC-68 (Vertical, C.R.I.)

1.64 4.44 20.80 0.27 13.50 1.57

0.38 0.39 0.76 0.61 0.39 0.95

1.61 1.64 4.13 2.60 1.64 20.89

Limit for positive testing

>1.10

>0.10

>1.15

Fluid Evaluation, Water Ionic pattern and salinity of formation water need to meet certain requirements to avoid side effects during the MEOR pilot test. Maximum limit in chlorides is considered safe when it has less than 100.000 p.p.m. PH is best near neutral. Blending water is also conditioned and monitored for total solid content and particulate size distribution (Figure 39) Reservoir Characterization Main Mechanism of drainage for both reservoir is due to gas expansion assisted by incipient artificial water drive. Waterflooding projects are not massive. Structurally the Cuyo basin is an extensive NW-trending depocenter that is limited by extension faults which were subjected to several movements. In Piedras Coloradas area, these tectonics movements formed an anticlinal structure that plunges to the southwest. This structure continues westward to the Tupungato field. A- Barrancas Fm. (C.R.I.) Poral geometry: Core testing using microporosity and capillary pressures converted into poral throat distribution show very large pore system with average values of 50 µm (Figures 4, 6). Effective interval: 8 m Petrophysical parameters End Point relative permeabilities values

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Kro(Swi): 0.46 Krw(Sor): 0.13 Swirr (%): 31.4 Sor (%): 23.3 Porosity (%): 16.8 Absolute Permeability (md): 120 Depth (m.b.s.): 1930 Reservoir Temperature (°F) 170 Original Reservoir Pressure (psi): 2285 Present Reservoir Pressure (psi): 569 Bubble Pressure (psi): 1023 GOR (M3/M3): 37 Bo factor (M3/M3 ): 1.176 Viscosity (cp, SR>20 s-1, 170°F): 4.5 (Roll Ball viscometer) API° (Bottom Hole Conditions): 32 Lithology: Conglomeradic and sandstone with variable interleaved shales and limonite components B- Rio Blanco member (V.O.) Poral geometry: The poral system is controlled by the quantity and type of cement, which is related to the amount of tuff ashes between the grains. Capillary pressures and electronic microscopy runs on core specimens were used to determine pore geometry characteristics. It follows a distinctive matrix monomodal distribution with poral throat mean values centered at 2 µm (Figures 3 and 5). Further evaluation has detected the presence of microscopic fractures. These small fractures, which are common in this tectonic framework contribute to the movement of fluids and permit microbes migration outward in the reservoir. Effective interval: 2-4 m Petrophysical parameters End Point relative permeabilities values Relative permeabilities Kro(Swi): 0.57 Krw(Sor): 0.36 Swirr (%): 30.6 Sor (%): 28.2 Porosity (%): 16.2 Absolute Permeability (md): 5-10 Depth (M.b.s.): 2030 Reservoir Temperature (°F) 180 Original Reservoir Pressure (psi): 3371 Present Reservoir Pressure (psi): 1279 Bubble Pressure (psi): 1026 GOR (M3/M3): 35 Bo factor (M3/M3 ): 1.154 Viscosity (cp, SR>20 s-1, 170°F): 4.5 (Roll Ball viscometer) API°(Bottom Hole Conditions): 32 Lithology: Good reservoirs are mainly related to the presence of sand associated with alluvial fan influx from the western flank of the basin. Deposition occurred under a persistent rain of ash, generating tuff and mixed rocks. Pilot Design Design of a pilot test is a complex task. To produce the best results in terms of degree of significance and discrimination it

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MICROBIAL ENHANCED OIL RECOVERY PILOT TEST IN PIEDRAS COLORADAS FIELD, ARGENTINA

is necessary to integrate a multidisciplinary team in biotechnology, reservoir, production and complementary areas (rheology and geochemical topics). The main issues behind pilot design is to achieve technical closure and good levels of correlation between controllable and uncontrollable groups of variables. The controllable variables are mainly MEOR treatment parameters. The uncontrollable variables are related with fluid and rock characteristics, which exert significant influence on MEOR response. Additional goals are to confirm feasibility indexes exhibited during laboratory testing. The pilot was designed to define microbial impact on productivity index for every treated well, completion method and reservoir in exploitation. A reasonable prediction capability between previous screening and post-MEOR results is another important objective. Discrimination in pre- and post-pilot data information and good “signal to noise ratio” are essential for a successful pilot. The trial needs to be programmed to see all relevant processes in time (pilot duration) and spatial dependence (number of wells, depth and structural position). Minimal time scale needs to be a twelve months period. Another important concept behind of pilot implementation is to reduce the uncertainty for all relevant measurement occurring during the pre- and post-MEOR stages. Finally, cost of pilot evaluation need to be consistent with expected benefits under different scenarios, risk and expansion strategies. Well Selection Six producer wells from a pool of 29 possible candidates (12 from Barrancas and 17 from Rio Blanco Fms.) were selected to implement the pilot according with following scheme: • Barrancas Formation: PC-19 (Vertical), PC-68 (Vertical) • Rio Blanco Formation: PC-1020 (horizontal), PC1022 (horizontal), PC-86 (Vertical), PC-94 (Vertical) Main reasons behind this selection are: 1. Adequate number of candidates to have sufficient statistical significance and good discrimination in wellby-well performance evaluation. 2. Non-marginal wells having consistent and clear fluid production histories. 3. Capable of discriminating microbial stimulation and EOR improvements in corresponding with control variables for each targeted reservoir (Barrancas Fm. and Rio Blanco Fm). 4. Wells producing oils with positive bio-treatability tests. 5. Adequate completion and extraction configuration. 6. Relevance to determining design consideration for future expansions. Operative aspects Treatments Initial microbial treatments were variable amount of microbeladen water (having neutral PH and with solid particulate control), followed by a 72 hour shut-in period. Subsequent

periodic treatments have been one third of initial volume every 15 days. Treatment design centers on seven items: 1. Method of inoculation based on well completion and extraction method (Figures 37 and 38). 2. Microbial community structure. 3. The total biotic concentration to use during initial and periodic treatments. 4. Blending and displacement water. 5. Microbial product structure (product participation). 6. Frequency of periodic inoculations. 7. Initial and periodic latencies (shut-in time) that follow every treatment. Horizontal wells. Initial inoculation was conducted by squeezing method according to diagram of Figure 40. Initial treatment size of 150 barrels was the minimum considered, based on a lateral diameter of 0.15 m. This size would provide a bio-reactor that the production would be in for one day as it traveled to the wellbore, if the entire 150 barrels were displaced into the formation. To ensure this the treatment size was increased by the capacity of the lateral from 150 to 220 barrels. If the formation would accept a larger treatment at low pressure, an initial treatment volume two to three times this might be considered. A higher microbe concentration in the maintenance treatments is advisable due the treatment size mandated by the length of the lateral. The formation needs to be over balanced in so that it can take fluid over the 3 day shut-in time. Periodic treatments were by batching using annulus space. The volume of microbe-laden water was calculated so that as the fluid level in the well gradually decreases, the fluid forced into the formation is microbe-laden and not displacement water. Using pressure build-up data, the bottom hole pressure at the end of three days was used to determine approximately what the fluid level in the well would be at the end of the shutin period, and the treatment was sized accordingly. Vertical wells. The initial treatment was designed to use a lower concentration than the maintenance treatment. Usually a 1: 210 dilution was used on the initial treatment (0.2 gal./bbl.) and a 1:84 dilution on the maintenance treatments (0.5 gal./bbl.). The rationale is that with the longer shut-in times the microbes have more time to grow and become established than with the shorter times normally used on maintenance treatments. For wells having a low average permeability limiting fluid input, higher concentration for the initial treatment is probably advisable. The maintenance (periodic) treatment size of 50 barrels was selected as a compromise between radius of microbial penetration and quick fractional flow stabilization after shut-in period. Results in Tupungato field validated this assumption. Both initial and periodic treatments were by annulus (Figure 41). The original program of treatments is summarized in Table 1. Product participation was P #1: 28.5%, P #4: 13.5%, P #5: 9.5% and P #6: 48.5%. Microbial sub-communities are presented in liquid medium as concentrates, having 106 - 108 viable microorganism per ml. Microbial liquid product (five

M. A MAURE, F. L. DIETRICH, V. A. DIAZ, H. ARGAÑARAZ

gallon drums) was stored out of direct sunlight and extreme weather conditions (+5 to +30 ºC), avoiding freezing temperatures. Project evaluation The inoculation program started March 1997 and continued for twelve non-consecutive months. Two reservoirs and six producer wells, two of them horizontals, were under a systematic program of inoculations using hydrocarbon degrading anaerobic-facultative microorganisms. A complete set of rheology parameters, specific geochemical fingerprints and biomarkers comparison was used to evaluate pre- and post-trial compositional alterations in produced fluids. Technical aspects Methodology to evaluate MEOR performance MEOR’s long-term distinctive response is to increase net oil rate and simultaneously to reduce Water Cut (Figures 07 to 18). This typical duality in MEOR response is explained by the change in apparent oil and water mobilities in the colonized portion of the reservoir, the bioreactor. Project Performance is evaluated well by well by tracking Productivity Index (P.I.) evolution (Eq. 1). Individual well testing into common battery and last generation echometry were used to have good data input for calculating and updating P.I. Four production tests per well per month, with confirmatory duplicate tests, were the usual monitoring to track project performance. Special care was taken to verify constancy in dynamic fluid levels pre- and post-MEOR. Pre-Meor adequate baselines for every well were calculated before starting the program of inoculations. Low noise (data scatter) allowing consistent decline curve determination is of the upmost importance for proper discrimination of microbial effects on well and reservoir productivity. Project evaluation is based on a customized set of MEOR Performance Curves (MPC), Eq. 2 with embedded rock-fluidmicrobiota parameters which are validated using field data. Annex B. The use of MEOR performance curve methodology is accomplished in four basic steps: • First, lab screening procedures are conducted to test rheology behavior in produced oils using control and inoculated samples for every well; • Second, Incremental Oil Rates (IOR) and Water Cut vs. time figures are forecast according to treatment design, reservoir and well completion information; • Third, predicted curves are correlated with field performance data during pilot implementation; providing insights and guidelines for process optimization and treatment design alteration, permitting assessment of MEOR prospects and offering practical guidelines during field implementation and pilot project follow-up monitoring; and • Fourth, economical models are run to calculate updated profitability indexes.

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Field data was matched using radial/elliptical flow model expressions considering concentric coupled zones of altered and original fluids. The model considers the oil as nonNewtonian, shear-rate-dependent fluid (Annex B). Mechanistic models could be easily adjusted to take into consideration horizontal completion geometry and permeability anisotropy. Net oil increment Evaluation of incremental oil was performed using reservoir simulations that consider two-parameter rheological models (Ostwald de Waele Nutting scheme, Annex B). Results are dimensionless time-dependent quotients of Productivity Indexes for the oil fraction before and after MEOR. The influence on MEOR response of petrophysic parameters is mainly associated with two aspects: 1. Microbial Migration Rate (MMR) is related to reservoir poral geometry (pore throats distributions); and 2. Shear Rate Field (SRF) is based on colonized reservoir and fluid flow dynamics and their connection with apparent viscosity. MMR correlate very well with how quickly the maximum MEOR response is obtained (improvement in Productivity Index, PI). This point will be depends on final radius of bacteria penetration and density of colonies in the corresponding reservoir poral spectra. SRF has a singular importance with shear rate sensitive oils (pseudoplastic behavior) and degree of compositional alteration. Figures 07 to 18, and 25 to 30 summarize pre- and post-MEOR oil production history. Composite performance is showing in next graph. Change in oil decline tendency before and after MEOR is clear and well defined. Incremental Oil averages 66% over baseline (dashed) with minimal values of 28.5% and maximum above 110%, in close correlation with oil °API variation: PC-19 , Pre: 19.3 , Post: 24.0 °API; PC-1020, Pre: 21.9, Post: 23.3 °API. 200 Qoi

Oil Rate (6 wells composite) Pilot_start

Qbase [M3/D]

ORm

150 t t 100

ORtot

ORtotm

0 1000

shift , T , T i x Time [days from MEOR start] t

shift , t , t

MEOR curve-type Baseline Incremental Oil Pre-MEOR production history Post-MEOR experimental points

1000

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MICROBIAL ENHANCED OIL RECOVERY PILOT TEST IN PIEDRAS COLORADAS FIELD, ARGENTINA

Water Cut Reduction Figures 8, 10, 12, 14, 16 and 18 summarize pre- and postMeor water cut evolution. Water cut tendencies for the sixwell composite is shown below. Water influx is decreasing in relation with oil. Change in water cut tendency is evident and is a clear indication of compositional and mobility alteration at reservoir conditions.

100

Water Cut (6 wells composite) Pilot_start

[%]

WRtot

WRtotm

clean-up of the productive interval and by new oil produced from original poor quality oil bearing zones. This increase is not a trend and might better be viewed as a baseline shift. Additional before and after MEOR samples from PC-19 (C.R.I. member) and PC-1020 (V.O. member) are currently under analysis. API gravity show a consistent and increasing trend: °API variation (lab normalized conditions) PC-19 Pre-MEOR: 19.3 Post-MEOR: 24.0 ∆: +4.7 PC-1020 Pre-MEOR: 21.9 Post-MEOR: 23.3 ∆: +1.4 Saturates hydrocarbons PC-19 Pre-MEOR: 62.2 PC-1020 Pre-MEOR: 57.1

80 i x

Post-MEOR: 66.9 Post-MEOR: 68.4

Light end alteration: C6 and C7 components PC-19 C6 C7 Pre-MEOR: 0.30% 0.57% Post-MEOR: 1.34% 2.08% 40 1000

1000

T ,T i x [Time from MEOR start, days]

Pre-MEOR history Post-MEOR experimental points

Experimental Design (E.D.) To analyze MEOR performance correlation with specific variations in treatment parameters a limited Experimental Design was conducted beginning mid-course in the original inoculation schedule. Mann-Whitney (Non parametric test, also named U proof) statistic procedure was used to verify degree of significance between treatment changes and MEOR response. Tables 2, 3 and 4, Figure 19, 20 and 21, summarize E.D. results: Segment Baseline-A: Clean up; BC: Microbial colonization; CD: Colony retraction (well is understimulated); DE: re-colonization after of concentration changes. Rheological comparison A clear and remarkable improvement in oil rheology was detected (Figures 33, 34, 35 and 36). Geochemical comparison A significant alteration in oil geochemical properties, biomarkers and fingerprints was detected. Figures 31 and 32 summarize the changes in Piedras Coloradas MEOR application. Light ends (S1) are mainly originated by enzymatic cracking on n-alkanes (S2), and their increase continues over the life of the project. On the other hand the increase in heavy compounds (S3, S5) occur during initial

PC-1020 Pre-MEOR: Post-MEOR:

C7 C6 0.68% 1.00% 0.82% 1.33%

Esteranes indicator The molecular change that correlate positively with microbial molecular attack is the decrease in the C29 Compounds in relation to the C27 counterparts. This decrease is readily apparent in the m/z 217 mass fragmentograms specific for steranes. Also, detectable is a significative increase in αββ isomers in respect to ααα (specially in C29 esteranes). Biomarkers A general increase in terms of absolute concentration (ppm) for the complete series of usual biomarkers such as C30 Hopane is observed: C30 Hopane (ppm) Status PC-19 PC-1020 Pre-MEOR: 1486 1326 Post-MEOR: 2048 2052 Note: 25-Norhophanes series was not detected in post-MEOR samples. Phenathrene/Dibenzothiophene ratio Status PC-19 PC-1020 Pre-MEOR: 14 9.5 Post-MEOR: 15.9 10.2

M. A MAURE, F. L. DIETRICH, V. A. DIAZ, H. ARGAÑARAZ

Quantified compounds (Methylnaphaftalenes, %) PC-19 Status MN DMN TMN MP Pre-MEOR: 2.79 18.30 26.79 22.69 Post-MEOR: 7.65 31.35 31.42 12.33 PC-1020 Status Pre-MEOR: Post-MEOR:

MN 8.53 8.92

DMN 26.29 29.64

TMN 27.57 32.42

MP 16.54 12.56

Where: MN, Methylnaphaftalenes; DMN, Dimethylnaphaftalenes; TMN, Trimethylnaphaftalenes; MP, Methylphenathrene. A progressive decrease in Aromatics, NSO and asphalthenes is detectable. Also observable is a clear variation in CPI (Carbon Preference Index) with increasing tendency in odd carbon chain predominance mainly in nC15 to nC27 range [Ref: 5, 8]. Biosafety issues MEOR bacteria used in Piedras Coloradas project are nonpathogenic. During the pilot, special care was taken to meet local and foreign regulation in regard to environmental and health topics Toxicity tests on animals and plants were done by the Institute of Microbiology (Academia Sinica) and by the Institute of Atom Energy Utilization, Chinese Academy of Agriculture Science, both in the Peoples Republic of China. Selected animals and plants were Kunming mice (200 individuals, weighting 18-20 grams., half-male, half-female) and Cucumber (Jinyan #5 strain) and rice (Yuefu strain) seeds respectively. Special essay protocols and method of exposure using microbial products number #1, #4, #5 and #6 were applied to germinated plants, seeds and animals under test. All results were no adverse affects for plants or animals. The microbial product caused no abnormalities in plants (rice and cucumber) and mice. No abnormality or disease occurred on different crops by different ways of treatment. No abnormality occurred of heart, liver, spleen, lung, kidney or intestine of test mice. Economical aspects Five year and longer forecasts using net present value curves based on adjusted individual well performance curves were calculated at project termination. Then an integrate set of NPV figures for the six well composite was calculated over a similar period with sensitivity and risk analysis. Different economic indexes like Pay-Out (break even point analysis), Exposure, and Internal Rates of Return (I.R.R.) were derived. Further analysis with floating scenarios of oil prices (from location-adjusted WTI of 17.5 to 10 $/barrel), taxes and treatment alternatives provide a detailed profitability evaluation (Tables 8, 9 and 10).

SPE 53715

Pay-Outs (PO) Based on a well by well analysis an average PO value of 75 days from pilot start was obtained. Cost per Incremental Barrel (CIB) CIB was 5.1 $/barrel during pilot stage. On MEOR Expanded scales, CIB is forecast to decrease to below 2 $/barrel. The difference is due to pilot trials being conducted at small scale, and being intensive in studies, operative support and engineering (Table 8). Incremental Reserves (IR) IR totalizes an optimized value of 141,800 M3 of oil at economic limits (<1 M3/D per well). A mean value of 50,000 M3 were assumed as conservative. Values were considering well-by-well analysis and the further integration of individual calculations for the composite (Table 9). Internal Rate of Return (IRR) IRR value is above 200% at average optimized prospects. Conclusions 1- MEOR is technically feasible in Piedras Coloradas field 2- Both formations test positive with similar performance figures. 3- MEOR on horizontal completions has interesting and positive effects in terms of restoring productive length and size of colonized areas. 4- MEOR is profitable at pilot and scaled stages. 5- A high correlation exists between the Piedras Coloradas and Tupungato-Refugio projects in both conditions and performance. 6- Multidisciplinary team integration and proper monitoring techniques are key factors to optimize fractional flow and incremental recovery in microbial stimulated reservoirs. Course of future actions 1- To conclude in-course optimization stage in a cluster of wells under treatment. 2- To evaluate best expansion strategies for vertical and horizontal wells to maximize economic return.. 3- To evaluate MEOR potential in waterflooding schemes. SI metric Conversion Factors acre-foot x 1.233 489 E+03 = barrel x 1.589 873 E-01 = foot x 3.048* E-01 = md x 9.869 233 E-04 = ml x 1.0 E-06 = psi x 6.894 757 E+00 = U.S.Gal x 3.785 412 E+00 = °F (°F -32)*5/9 E-01 = * Conversion factor is exact

m3 m3 m µm2 m3 kPa L °C

Acknowledgements We want to thank to Perez Companc Company and Microbes Inc. for permission to publish this paper. Special thanks to Piedras Coloradas directive staff and operative team for

SPE 53715

MICROBIAL ENHANCED OIL RECOVERY PILOT TEST IN PIEDRAS COLORADAS FIELD, ARGENTINA

valuable discussion, follow-up effort and contribution to interpret MEOR field data. We also thank Alfredo Rezinovsky, for his assistance in preparing this manuscript. References 1. Microbial EOR Technology Advancement: Case Studies of Successful Projects. F.L. Dietrich, SPE, F.G. Brown, SPE, Z.H.Zhou, SPE, Microbes, Inc.; and M.A.Maure, SPE, Green Consultores. SPE 53715. 2. Geochemical Report, Source Rock Evaluation of the PCXP 1002 Well and Characterization of Five Oils, Piedras Coloradas Field, Cuyo Basin, Argentina, October 1988, Exlog Consulting Services. 3. Wettability Literature Survey - Part 2 :Wettability Measurement. William G. Anderson, SPE, Conoco Inc. Journal of Petroleum Technology, November 1986. 4. Effect of Wettability Alteration on Water/Oil Relative Permeability, Dispersion, and Flowable Saturation in Porous Media. F.H.L. Wang, SPE, Exxon Production Research Co. SPE Reservoir Engineering, May 1988. 5. New Tools Target Oil-Quality Sweet Spots in Viscous-Oil Accumulations. P.C. Smalley, SPE, and N.S Goodwin, BP Exploration ; J.F. Dillon and C.R. Bidinger, BP Exploration (Alaska) Inc. ; and R.J. Drozd, IITRI. SPE 36652. 6. Microbial-Enhanced Waterflooding : Mink United Project. Rebecca S. Bryant, SPE, and Thomas E. Burchfield, SPE, Natl. Inst. for Petroleum & Energy Research ; DM. Dennis, Microbial System Corp. ; and D.O. Hitzman, Injectech Inc. SPE 17341. 7. Calculating Viscosities of Reservoir Fluids From Their Compositions. John Lohrenz, Bruce G. Bray, Members AIME, Charles R. Clark. Continental Oil Co, Ponca City , Okla. U. of Kansas. Lawrence , Kans. Paper presented at SPE Annual Fall Meeting, held in Houston, Tex., Oct. 1114-1964. 8. Pieter Shenck Award acceptance speech Geochemical indicators of biodegradation : tools for developing and managing heavy oil assets (17th. International Meeting on Organic Geochemistry, Donostia- San Sebastian, September 6, 1995). Mark A. McCaffrey. 9. A Genome Probe Survey of the Microbial community in Oil Fields. Voordouw. G. ; Telan , A. J. Department of Biological Sciences, The University of Calgary, Alberta, T2N 1N4, Canada. 10. Surfactant - Base EOR Mediated by Naturally Occurring Microorganisms. CP. Thomas, SPE, M.L. Duvall, SPE, E.P. Robertson, SPE, K.B. Barrett and G.A. Bala, SPE, EG&G Idaho Inc.. SPE 22844. 11. A Prediction Technique for Inmiscible Processes Using Field Performance Data. Iraj Ershaghi, SPE, U. of Southern California. Doddy Abdassah, SPE, U. of Southern California. SPE 6977. 12. Crude Oils in Reservoirs : The Factors Influencing their Composition. Chapter I. 6. Ph. Blanc and Connan. (Elf

13.

14.

15.

16.

17.

18. 19.

20.

21. 22.

23.

24.

25.

Aquitaine , Centre Scientifique et Technique Jean Feger 64018 Pau Cedex, France.) Laboratory Testing of a Microbial Enhanced Oil Recovery Process Under Anaerobic Conditions. Bruce Rouse, Franz Hiebert, and L.W. Lake, U. of Texas. SPE 24819. A Mathematical Model for Microbially Enhanced Oil Recovery Process. Xu Zhan, R.M. Knapp, and M.J. Mclnerney, U. of Oklahoma. SPE/DOE 24202. Mathematical Modeling of Microbial Enhanced Oil Recovery. M. R. Islam, U. of Alaska-Fairbanks. SPE 20480. MEOR - Altamont/ Bluebell Field Project. L.P. Streeb, Coastal Oil & Gas Corp., and F.G. Brown, Natl. Parakleen Co.. SPE 24334. A Study of Formation Plugging with Bacteria. J.T. Raleigh. D.L. Flock. Members AIME . The U. of Alberta. Edmonton, Alta. Journal of Petroleum Technology, July 14, 1964. Microbes Deep inside the Earth. James K. Fredrickson and Tullis C. Onstott. Scientific American, October 1996. Optimization of Microbial formulations for Oil Recovery : Mechanisms of Oil Mobilization, transport of Microbes and metabolities , and Effects of Additive. R.S. Bryant, T.E. Burchfield, K.L. Chase, K.M. Bertus, and A.k. Stepp, IITRI/NIPER. SPE 19686. A Parametric Comparison of Horizontal and Vertical Well Performance. Hemanta Mukherjee and Michael J. Economides. Dowell Schlumberger. SPE 18303. Productivity of a Horizontal Well. D.K. Babu and A.S.Odeh, Mobil R&D Corp.. SPE 18298. Augmentation of Well Productivity with Slant and Horizontal Wells. SD.Joshi, SPE, Phillips Petroleum Co. SPE 15375. Dimensionless Methods for the study of particle settling in Non-Newtonian Fluids. Liang Jin, SPE, and Glenn S. Penny, SPE, Stim-Lab Inc. SPE 28563. The Transport of Bacteria in Porous Media and its Significance in Microbial Enhanced Oil Recovery. Long Kuan Jang, M.M. Sharma, and T.F. Yen, U of Southern California. SPE 12770. Advances in the characterization of microbial populations in the subsurface. Ian Head. NRC News, May 1996, Subsurface Microbial Populations.

M. A MAURE, F. L. DIETRICH, V. A. DIAZ, H. ARGAĂ&#x2018;ARAZ

SPE 53715

Tables

Treatment Design (original) Well PC-1020 H (V.O.) PC-1020 H (V.O.) PC-68 (B.R.C.) PC-19 (B.R.C.) PC-94 (V.O.) PC-86 (V.O.)

Start Date [dd/mm/aa] 17/3/97 03/04/97 31/03/97 27/03/97 24/03/97 20/03/97

C.I. [Gal] 63 63 63 63 63 63

L.I. [hs] 72 72 72 72 72 72

C.P. [gal] 9 15 8 8 8 7

L.P. [hs] 24 24 24 24 24 24

Frequency [T/month] 2 2 2 2 2 2

Method *Squeeze/Batch *Squeeze/Batch Batch Batch Batch Batch

C.I.: Initial Concentration of Microbial Concentrates (P#1,P#4, P#5 and P#6) L.I.: Latency (initial shut-in time) C.P.:Periodic Concentration L.P.:Latency (Periodic shut-in time) Frequency: Treatments per month * Inoculation method, Squeeze only for Initial Treatment Table 01: MEOR, Inoculation parameters

Treatment modifications (Experimental Design) Well

Original concentration Time interval [gals]

PC-1020 H (V.O.) PC-1020 H (V.O.) PC-68 (C.R.I.) PC-19 (C.R.I.) PC-94 (V.O.) PC-86 (V.O.)

17/3 - 15/5 3/4 - 15/5 31/3 - 15/5 27/3 - 15/5 24/3 - 15/5 20/3 - 15/5

9 15 8 8 8 7

Modified Percentage concentration of change Time [gals] interval 15/5 - 15/6 20 +122 % 15/5 - 15/6 25 +66 % 15/5 - 15/6 16 +100 % 15/5 - 15/6 8 0% 15/5 - 15/6 8 0% 15/5 - 15/6 14 + 100 %

Table 02: MEOR, sensitive analysis on concentrations

Oil rate comparison ORo [M3/D] Well PC-1020 H (V.O.) PC-1020 H (V.O.) PC-68 (C.R.I.) PC-19 (C.R.I.) PC-94 (V.O.) PC-86 (V.O.)

Pre-MEOR 8.8 19.9 3.9 2.3 13.6 8.0

ORm1 [M3/D] Post-MEOR Phase 1

ORm2 [M3/D] Post-MEOR Phase 2

ORm3 [M3/D] Post-MEOR Post. Modif.

18.3 33.9 4.4 4.4 23.9 8.2

13.0 14.6 5.9 8.3 15.5 6.7

17.0 20.7 6.1 Unmodified Unmodified 11.7

Table 03: MEOR, Experimental Design results

SPE 53715

MICROBIAL ENHANCED OIL RECOVERY PILOT TEST IN PIEDRAS COLORADAS FIELD, ARGENTINA

Water Cut comparison

Pre-MEOR

Wcm1 [%] Post-MEOR Phase 1

Wcm2 [%] Post-MEOR Phase 2

Wcm3 [%] Post-MEOR Post. Modif.

64.0 72.5 68.6 86.6 62.3 56.6

39.0 44.0 67.5 72.3 51.6 54.5

45.8 70.7 65.0 72.8 58.7 63.3

39.1 59.5 55.6 Not modified Not modified 40.0

Wc [%] Well PC-1020 H (V.O.) PC-1020 H (V.O.) PC-68 (C.R.I.) PC-19 (C.R.I.) PC-94 (V.O.) PC-86 (V.O.)

Table 04: MEOR, Experimental Design results

Oil viscosity comparison

Well

PC-1020 H (V.O.) PC-1020 H (V.O.) PC-68 (C.R.I.) PC-19 (C.R.I.) PC-94 (V.O.) PC-86 (V.O.)

µ apparent Pre-MEOR Control [cp] 270-340 70 380 330 148 275

Laboratory [cp]

170 62 20 200 50 73

µ apparent Post-MEOR Series 1 [cp] 50 51 20 20 37 62

µ apparent Post-MEOR Series 2 [cp] 65 57 25 9 39 55

Temp. [°F]

100 95 170 180 130 94

Table 05: MEOR, Oil viscosity alteration at MDT temperatures and below SR: 1 s-1

Geochemical parameters Well PC-1022 PC-19 LL-7

Pristane/nC-17 Phytane/nC-18 Obs. 0.22 0.13 Rio Blanco Fm. (P. Coloradas) 0.26 0.14 Barrancas Fm. (P. Coloradas) 5.02 13.51 Llancanelo (extremely biodegrated oil) Table 06: MEOR, Natural biodegration status in Piedras Coloradas oils

MEOR performance

Well PC-1020 H (V.O.) PC-1022 H (V.O.) PC-68 (C.R.I.) PC-19 (C.R.I.) PC-94 (V.O.) PC-86 (V.O.)

IOR: (MEOR365 –1) x 100 [% over baselines]

Oil Rates [M3/D] Values at pilot start

118 68 92 97 124 60

8.8 19.9 3.9 2.3 13.6 8.0

Table 07: MEOR, Incremental Oil (Optimized, mid term inference)

M. A MAURE, F. L. DIETRICH, V. A. DIAZ, H. ARGAĂ&#x2018;ARAZ

Economic Analysis

Well PC-1020 H (V.O.) PC-1020 H (V.O.) PC-68 (C.R.I.) PC-19 (C.R.I.) PC-94 (V.O.) PC-86 (V.O.)

VAN365 [M$]

VAN1825 [M$]

Pay Out [Days]

112 88 36 48 181 130

324 278 212 113 792 583

91 108 88 75 36 51

C.B.I. [$/Incremental barrel] 4.8 5.7 7.3 6.5 2.6 3.8

Table 08: MEOR, Profitability and cost parameters

Incremental Reserves and Economic Limits

Well

PC-1020 H (V.O.) PC-1020 H (V.O.) PC-68 (C.R.I.) PC-19 (C.R.I.) PC-94 (V.O.) PC-86 (V.O.)

Incremental Reserves at economic limit [MEOR - Conventional] [Mm3] 18.7 - 9.8 25.7 - 11.1 17.5 - 17.5 8.4 - 3.7 39.7 - 39.7 31.8 - 31.8

Shiftment in economic limits from Meor start [MEOR - Conventional] [Days] 2891 - 1890 3591 - 2822 1825 - 1825 * 1999 - 1188 3650 - 3650 * 3650 - 3650 *

Table 09: MEOR, comparative analysis (*, Economic limit is not reached)

Well

PC-1020 H (V.O.) PC-1020 H (V.O.) PC-68 (C.R.I.) PC-19 (C.R.I.) PC-94 (V.O.) PC-86 (V.O.)

Investment First inoculation Alt. 1, alt 2 [M$ - M$] 17.2 - 18.2 17.2 - 18.2 4.2 - 5.2 4.2 - 5.2 4.2 - 5.2 4.2 - 5.2

Periodic inoculations program (annual cost) Alt. 1, alt 2 [M$ - M$] 52.9 - 44.0 52.0 - 44.0 44.8 - 37.5 48.0 - 40.7 40.7 - 34.4 42.3 - 35.8

Table 10: MEOR, Range of Investment and Annual cost for two alternatives of treatments in Piedras Coloradas field

SPE 53715

MICROBIAL ENHANCED OIL RECOVERY PILOT TEST IN PIEDRAS COLORADAS FIELD, ARGENTINA

Figures

Quaternary 1800 M

Terciary Barrancas Formation Triasic

2100 M

A Member B Member C Member

Paleozoic 2050 M

Complex A Upper Member

Rio Blanco Formation

Piedras Coloradas Field (Cuyo Basin, Argentina)

Medium Member

Layer A-1 Layers C, D

Lower Member 2400 M

Figure 1: Field Location

Figure 2: Target Reservoirs Rio Blanco Fm. ( V.O )

Barrancas Fm. (B.R.C.)

Bacteria Bacteria Size Size Range Range

Bacteria Size Range

Frecuency [ % ]

20 15 10

5 0

0.1

100

Poral throat diameter [Microns ]

0.1

100

Poral throat diameter [ Microns ]

Figure 3: Rio Blanco Fm., Poral Distribution and Bacteria Size

Figure 4: Barrancas Fm., Poral Distribution and Bacteria Size

Figure 5: Rio Blanco Fm., Pore Structures

Figure 6: Barrancas Fm., Pore Structures

M. A MAURE, F. L. DIETRICH, V. A. DIAZ, H. ARGAĂ&#x2018;ARAZ

Oil rate [M3/D]

SPE 53715

Water cut [%]

100 100

Pilot_start ORa

Pilot_start WCa

ORma

WCma

30 0 3000

2000

1000

T ,T i x

3000

1000

[Time from MEOR start, days]

ORmb

Oil rate [M3/D]

100

Water cut [%]

100

Pilot_start WCb

WCmb

30 0 3000

2000

1000

T ,T i x

3000

1000

3000

1000

Oil rate [M3/D]

Figure 10: Well PC-94, Water cut Response (V.O. Formation)

100

Water cut [%]

100

Pilot_start

Pilot_start WCc

ORmc

1000 1000

Pre-Meor Post-Meor

Figure 9: Well PC-94, Production Response (V.O. Formation)

ORc

T ,T i x [Time from MEOR start, days]

Pre-Meor Post-Meor

2000

3000

[Time from MEOR start, days]

1000 1000

Figure 8: Well PC-86, Water Cut Response (V.O. Formation)

Pilot_start ORb

Pre-Meor Post-Meor

Figure 7: Well PC-86, Production Response (V.O. Formation)

1000 T ,T i x

[Time from MEOR start, days]

Pre-Meor Post-Meor

2000

3000

WCmc

0 0 3000 3000

2000

1000

T ,T i x

1000 1000

[Time from MEOR start, days]

Pre-Meor Post-Meor Figure 11: Well PC-19, Production Response (B.R.C. Formation)

0 3000 3000

2000

1000

T ,T i x

1000 1000

[Time from MEOR start, days]

Pre-Meor Post-Meor Figure 12: Well PC-19, Water Cut Response (B.R.C. Formation)

SPE 53715

MICROBIAL ENHANCED OIL RECOVERY PILOT TEST IN PIEDRAS COLORADAS FIELD, ARGENTINA

Oil rate [M3/D]

100

Water cut [%]

100

Pilot_start

ORd i

WCd

ORmd x

WCmd

0 3000

2000

1000

T ,T i x

3000

0 3000

1000 1000

1000

Oil rate [M3/D]

Figure 14: Well PC-68, Water Cut Response (B.R.C. Formation)

100

Water cut [%]

100

Pilot_start

WCe i

WCme x

ORme x

0 0 2000

1000

0 T ,T i x

2000

1000

1000 1000

Pre-Meor Post-Meor

Figure 15: Well PC-1020, Production Response (V.O. Formation)

Oil rate [M3/D]

Figure 16: Well PC-1020, Water Cut Response (V.O. Formation) 100

Water cut [%]

100

Pilot_start

ORf i

WCf i

ORmf x

0 T ,T i x

[Time from MEOR start, days]

Pre-Meor Post-Meor

100

1000

2000

1000

[Time from MEOR start, days]

100

1000 1000

Pre-Meor Post-Meor

Figure 13: Well PC-68, Production Response (B.R.C. Formation)

ORe i

T ,T i x [Time from MEOR start, days]

Pre-Meor Post-Meor

2000

3000

[Time from MEOR start, days]

WCmf x

60 0

40 0

40 1000 1400

0 T ,T i x

1000 1000

[Time from MEOR start, days]

Pre-Meor Post-Meor Figure 17: Well PC-1022, Production Response (V.O. Formation)

1000 1500

0 T ,T i x

1000 1000

[Time from MEOR start, days]

Pre-Meor Post-Meor Figure 18: Well PC-1022, Water Cut Response (V.O. Formation)

M. A MAURE, F. L. DIETRICH, V. A. DIAZ, H. ARGAĂ&#x2018;ARAZ

Piedras Coloradas - Well: PC-1020 (H)

30 OR

Tmeor_start

Qcp v Oil Rate (M3/D]

Tecon_lim

Qcp v

Qcp v ORm

SPE 53715

3 15 u

Qcpmx kj Qcpmy

Qcpmz kj

Econ_lim

0 1500

1000

500

1000

1500

2000

2500

3000

T , Tx , Tx , Tx , Tm , kj , kj , kj v v u i v Time (days)

Figure 19: MEOR Response, Control Bands On Baselines and Curve-Type sensitive Analysis

67.97

Water Cut [%]

Tmeor_start

OR i

Net oil (m3/day]

WCm

Tmeor_start

Qh v

60 WC

Oil Rate (M3/D)

A co

Qh v

ORm

17.36

Qcp v

D u

0.663

0 200 300

0 T , Tm i u Time (days)

Figure 20: Water Cut Response in Horizontals

200 200

0 200 300

T , Tx , Tx , Tx , Tx , Tm i v v v v u Time (days)

Figure 21: Oil Rate Response and Controllability

200 200

SPE 53715

MICROBIAL ENHANCED OIL RECOVERY PILOT TEST IN PIEDRAS COLORADAS FIELD, ARGENTINA

Oil rates [M3/D]

15 OR

Tmeor_start

Wellbore Clean-Up

Qh v

Reservoir colonization

Qcp v ORm

10 u

Qcpl w Qm1 Qm0 Qm2

y y

Qcup y

Econ_lim

0 2000

1500

1000

500

T , Tx , Tx , Tm , Tx , Ty , Ty , Ty , Tyc v u w y y y y i v Time (days)

Figure 22: MEOR Clean-up effect discrimination from Reservoir Colonization Behaviour (PC-19 (Barrancas Fm.))

Water Cut [%]

100

Oil Rates [M3/D]

15 00

Tmeor_start 72.8

80 i

QWcp

QWcpm1 QWcpm2 WCm

Baseline

Qh v

U 10

Qcp v

ORm

Qcpl w

QWcpp

I Qm1

Econ_lim

0 500

0 T , Tx , Tx i v v

20 , Tx

v Time (days)

500 10 , Tm , Txq u q

Figure 23: Water Cut Evaluation Using MEOR Curve-Type Analysis

500

T , Tx , Tx , Tm , Tx , Ty i v v u w y Time (days)

Figure 24: Long Term MEOR Response need to be evaluated using V-W curve segment and after clean-up baseline (dashed decline baseline, " I " difference)

M. A MAURE, F. L. DIETRICH, V. A. DIAZ, H. ARGAĂ&#x2018;ARAZ

100

Oil Rate [M3/D]

SPE 53715

Water cut [%]

100 Pilot_start

ORtot

Pilot_start WRtot

ORtotm

WRtotm

x 60

0 1000

500

40 1000

500

T ,T i x [Time from MEOR start, days]

Pre-Meor Post-Meor

Pre-Meor Post-Meor Figure 25: MEOR Perfomance (Six Well Composite) 20

500

Figure 26: MEOR Perfomance (Six Well Composite)

Oil Rate [M3/D]

100

Water cut [%] Pilot_start

Pilot_start 15 ORtot

WRtot

ORtotm

WRtotm

i x

0 1000

500

40 1000

500

T ,T i x [Time from MEOR start, days]

0 T ,T i x [Time from MEOR start, days]

Figure 27: MEOR Performance (Barrancas Fm.)

Figure 28: MEOR Performance (Barrancas Fm.)

Oil Rate [M3/D]

Water cut [%] Pilot_start

Pilot_start ORtot

ORtotm

WRtot

WRtotm

20 1000

500

Pre-Meor Post-Meor

500

x 40

500

T ,T i x [Time from MEOR start, days]

Pre-Meor Post-Meor Figure 29 MEOR Performance (Rio Blanco Fm.)

30 1000

500

T ,T i x [Time from MEOR start, days]

Pre-Meor Post-Meor Figure 30: MEOR Performance (Rio Blanco Fm.)

SPE 53715

MICROBIAL ENHANCED OIL RECOVERY PILOT TEST IN PIEDRAS COLORADAS FIELD, ARGENTINA

PC-1022 - Normal Alkanes

p.p.m.

0 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 Carbon order

Pre-Meor Post-Meor PC-1022 - Branched Alkanes

p.p.m.

0 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 Carbon order

Pre-Meor Post-Meor Figure 31: MEOR, Geochemical Signature (Rio Blanco Oil, Horizontal Completion)

PC-19 - Normal Alkanes

p.p.m.

0 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 Carbon order

Pre-Meor Post-Meor PC-19 - Branched Alkanes

p.p.m.

0 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 Carbon order

Pre-Meor Post-Meor Figure 32: MEOR, Geochemical Signature (Barrancas Oil, Vertical Completion)

M. A MAURE, F. L. DIETRICH, V. A. DIAZ, H. ARGAĂ&#x2018;ARAZ

Viscosity vs Temperature

1500

Viscosity [mpa.s] vs. shear rate [1/s]

450

T3, Field

Viscosity [mpa.s]

400

100

350 Viscosidad (mPa.s)

500

350 300

Control

250

SPE 53715

Reservoir_temperature

1000

500

200

Lab Inference

150 100

50 10

T5, Field

0 0

180

200

Viscosity vs Temperature

2000

Reservoir_temperature

350

400 350

1500

300 Viscosidad (mPa.s)

Viscosity [mpa.s]

160

Figure 34: Pour and Cloud Point alteration, PC- 1020 H

Viscosity [mpa.s] vs. shear rate [1/s]

450

140

Control, Pre-Meor Control, Pre-Meor (duplicate) In-Vitro biodegradation, Pre-Meor Lab Inference Post-Meor (after third treatment), field sample Post-Meor (after third treatment), duplicate Post-Meor (after fifth treatment), field sample Post-Meor (after fifth treatment), duplicate

Control at Low Shear Rate (Pre-Meor) Lab biodegradated (Pre-Meor inference) Lab biodegradated (Pre-Meor inference, duplicate) Post-Meor (after fifth treament) Post-Meor (after third treatment)

500

120

Temperatura (F. deg.)

Shear rate [1/s]

Figure 33: Rheological Signature, PC- 1020 H

100

250 200 150 100

1000

50 0 0

340

500

180

Shear rate [1/s]

Control at Low Shear Rate (Pre-Meor) Lab biodegradated (Pre-Meor inference) Lab biodegradated (Pre-Meor inference, duplicate) Post-Meor (after fifth treament) Post-Meor (after third treatment) Figure 35: Rheological Signature, PC-19 (Vertical)

0 80

100

120

140

160

180

200

Temperatura (F. deg.)

Control, Pre-Meor In-Vitro biodegradation, Pre-Meor Lab Inference Post-Meor (after third treatment), field sample Post-Meor (after third treatment), duplicate Post-Meor (after fifth treatment), field sample Post-Meor (after fifth treament), duplicate Figure 36: Pour and Cloud Point alteration, PC- 19 (Vertical)

SPE 53715

MICROBIAL ENHANCED OIL RECOVERY PILOT TEST IN PIEDRAS COLORADAS FIELD, ARGENTINA Piedras Coloradas Field

Piedras Coloradas Field

PC-1020 (Horizontal)

PC-19

Production Data (April 97) SRP lifting device

Oil: 8.8 M3/D Water Cut: 64 %

Oil:

2.3 M3/D

Water Cut: 86 %

GOR < 100

Tbg. 2 7/8" - J55 - 6.5 lb/ft

Csg. 7"- J55 - 23 lb/ft.

Dynamic Fluid Level (1818 M) Pump Intake (2008.6 M)

Dynamic Fluid Level (1473 M) Anchor 7" x 5" Barrancas Fm. Pump Intake (2093.6 M)

Slotted liner 5"- 15 lb/ft. Rio Blanco Fm.

2009/2127 M SBHT: 170 F SBHP: 498 psi

2059 - 2672 (T.D.) M SBHT: 180 F SBHP: 1560 psi

Horizontal lenght 500 M

2126 M

Figure 38: Vertical Completion and extractive system

Figure 37: Horizontal completion and extractive system

100000

PC-7

Concentrations in mg/liter

10000

C O 3C a

PC-13 PC-68

1000

PC-86 PC-19

C O 3H

PC-94

100

PC-1020

SO 4 10

PC-1022

T-80

Mg 1

FIgure39: Formation Water, Typical Ionic Pattern

M. A MAURE, F. L. DIETRICH, V. A. DIAZ, H. ARGAĂ&#x2018;ARAZ

Step 01 Blending formulation by diluting microbial cultures in formation water

SPE 53715

Step 02 Microbial blending injection by annulus (1 to 2 BPM) Piedras Coloradas Field PC-1020 A

Positive displacement pump

Blending area

Piedras Coloradas Field Prod#1

PC-1020 (Horizontal) Tbg. 2 7/8" - J55 - 6.5 lb/ft

Prod#4 Microbial concentrates (From five gallons drums)

Csg. 7"- J55 - 23 lb/ft.

References Produced fluids

Prod#5

Dynamic Fluid Level (1818 M)

Displacement water Retrievable Packer

Pump Intake (2008.6 M)

Prod#6

Microbial Blend

Anchor 7" x 5" Slotted liner 5"- 15 lb/ft.

Rio Blanco Fm.

Formation water used for blending (150 bbls.)

Formation water used for displacement (Variable from well to well)

Step 03

Step 04

Low Rate Squeeze into formation

Shut-in period (latency)

2059 - 2672 (T.D.) M SBHT: 180 F

Horizontal lenght 500 M

SBHP: 1560 psi

Step 05 Well is restablished to production using standard pulling operation

The well is closed during 72 hours.

Positive displacement pump

Oil Water Gas

Closed Tbg. 2 7/8" - J55 - 6.5 lb/ft

Tbg. 2 7/8" - J55 - 6.5 lb/ft

Csg. 7"- J55 - 23 lb/ft.

Retrievable Packer

Csg. 7"- J55 - 23 lb/ft.

Dynamic Fluid Level Pump Intake Anchor 7" x 5"

Anchor 7" x 5" Rio Blanco Fm.

Critical Penetration Radii according with Kv/Kh permeabilities ratio

Figure 40: Operative Procedure used to Inoculate Horizontal Wells (Initial Treatment), PC-1020 H

Slotted liner 5"- 15 lb/ft.

SPE 53715

MICROBIAL ENHANCED OIL RECOVERY PILOT TEST IN PIEDRAS COLORADAS FIELD, ARGENTINA

Step 01 Blending formulation diluting microbial cultures in formation water

Step 02 Microbial blending injection by annulus (1 to 2 BPM) Piedras Coloradas Field PC-19 A

Positive displacement pump

Blending area

Prod#1 SRP lifting device

Prod#4 Microbial concentrates (From five gallons drums) Tbg. 2 7/8" - J55 - 6.5 lb/ft

Prod#5

Csg. 7"- J55 - 23 lb/ft. Prod#6

Formation water used for blending (20 to 50 bbls.)

Dynamic Fluid Level (1473 M)

Formation water used for displacement (Variable from well to well)

Barrancas Fm. Peforated interval 2009/2127 M SBHT: 170 F SBHP: 498 psi

Pump Intake (2093.6 M)

2126 M

Step 03

Step 04

Step 05

Low Rate Gravity Displacement into formation

Shut-in period (latency)

Well is restablished to production

The well is closed during 24 hours.

References Produced fluids Displacement water

Positive displacement pump

Microbial Blend

Oil Water Gas

Static Fluid Level Dynamic Fluid Level

Barrancas Fm. Peforated interval

Critical Radius 2126 M

2126 M

Figure 41: Operative Procedure used to Inoculate Vertical Wells (Initial and Periodic Treatment), PC-19 V

2126 M

M. A MAURE, F. L. DIETRICH, V. A. DIAZ, H. ARGAÑARAZ

Annex A

Viscosity [mpa.s] vs. shear rate [1/s]

60 1

NI µapp

control minSR

inoculated minSR

control maxSR

µapp µapp

maxSR

TMD inoculated

µapp

i = minSR

48 45 42 39

maxSR control

µapp

i = minSR i

1 (1

DV )

minSR

Newtonian Index

Delta Viscosity

EOR

Enhanced Oil Recovery index

minSR

Minimum explored Shear Rate, [1/sec]

maxSR

Maximum explored Shear Rate, [1/sec]

µapp µapp TMD

control

minSR

control i inoculated i

Apparent viscosity measured at min SR on control oil Apparent viscosity measured at SR (i ) on control oil Apparent viscosity measured at SR (i ) on inoculated oil Temperature of Maximun Discrimination of rheological properties

Figure 42: Methodology to subcommunities (1 to 6, BB) in oils Tg2

maxSR

SRi

analize

MEOR

microbial

Viscosity vs Temperature

2000 92

Reservoir_temperature

1500 Viscosidad (mPa.s)

10 Shear rate [1/s]

1+ 2+ 3 4 5 6 BB Control

Where:

µapp

inoculated

µapp

EOR

control

µapp

maxSR

i = minSR

inoculted maxSR

control

µapp

TMD

Viscosity [mpa.s]

µapp

SPE 53715

Rcontrol 1000

R5 R3

500

340 180

Ts tg1

0 80

100

120

140

160

180

200

Temperatura (F. deg.) TMD Control, Pre-Meor In-Vitro biodegradation, Pre-Meor Lab Inference Post-Meor (after third treatment), field sample Post-Meor (after third treatment), duplicate Post-Meor (after fifth treatment), field sample Post-Meor (after fifth treament), duplicate

Figure 43: Compositional changes in treated (lab, field) and untreated samples (control). Rcontrol, R3 and R5 are indicators of molecular homogeneity, Ts is the shift in precipitation points.

SPE 53715

MICROBIAL ENHANCED OIL RECOVERY PILOT TEST IN PIEDRAS COLORADAS FIELD, ARGENTINA

Annex B

Radial model case

Qmeor Pe MEOR t

MEOR t

Pwfmeor t Qo

B C

Declined oil production (convtentional), [BOPD]

Qmeor t

Pwf t , Pwfmeor t i

Enhanced oil production [BOPD]

C i

Static reservoir pressure, [psi]

1 t

Elapset time from MEOR start [days]

.D .P .ζ .δ i

etv

RDie t

1 ξ

etv i

RDiw t

etmv i

etmv

ν.

Dynamics pressures, [psi]

Associated equations

where:

Pwf t

with: A

η .Factor

Ktmv Ktv 1 1

ntv ntmv 2 .10 24.3600. π 6

Factor

Scale factor

Qo (ti), Qw(ti), Qg(ti)

Rm, R(ti)

Sw,So Swirr, Sor Kro,Krw,Kabs Ø

Vertical Section PC-68, PC-19 (Barrancas Fm.) PC-86, PC-94 (Rio Blanco Fm)

Ktv,ntv Ktmv,ntmv Effective Lenght, L

Horizontal Section, PC-1020, PC-1022, Rio Blanco Fm. Figure 44: Simplified diagram showing completions and colonized zones (bioreactors) coupled with untreated outer areas

DIETRICH F.A., MAURE M.A, DIAZ V.A., ARGAÑARAZ H.

Annex C Geochemical Methods and instrumentation Fractionation by Liquid Chromatography: Asphaltenes are precipitated with hexane and soluble fraction is separated into saturate hydrocarbons, aromatic hydrocarbons and resins/NSO compounds on a silica column by successive elutions with hexane, benzene, and benzene-methanol. The solvents are evaporated and weight percent of each fraction is determined. Gas Chromatography (GC): The whole oil is analyzed with a Varian model 3300 gas chromatograph fitted with a 50 m fused silica capillary column. Analytical data are processed with a Nelson Analytical Model 3000 chromatography data system. Very High Resolution C7 Gas Chromatography: A sample of oil is injected directly into a Varian model 3400 gas chromatograph fitted with a split injector and a Quadrex 100 meter fused silica capillary column. The GC run is isothermal at 35°C while collecting the data from C2 – C8 , then heated to purge the remaining sample from the column. Analytical data are processed with a Nelson Analytical model 3000 chromatographic data system and IBM computer hardware. Biomarker Analysis (GC-MS): The saturate or aromatic fractions separated by liquid chromatography from whole oils or source rocks extracts are injected into a HP5890 gas chromatograph coupled to the HP5971A MSD. The Selected Ion Monitoring (SIM) capabilities of the computer data acquisition system permit specific ions to be monitored. Ion m/z = 191 allows characterization of specific saturate triterpenoid compounds and m/z = 217 certain saturate steranes. The ions m/z = 253 and 231 are respectively specific for mono and triaromatic steroids; m/z = 156 and 170, for C2– naphthalenes; m/z = 178 and 192, for phenanthrene and methylphenanthrenes, respectively; m/z = 184 and 198, for dibenzothiophene and methyldibenzothiophene, respectively.

SPE 53715

MICROBIAL ENHANCED OIL RECOVERY PILOT TEST IN PIEDRAS COLORADAS FIELD, ARGENTINA

Nomenclature

ψ = anisotropy factor µ k = apparent viscosity based on Ostwald de Waele Nutting rheological model, [cp] α = apparent viscosity relationship after and before MEOR evaluated at 1 sec –1 (shear rate), [cp] µapp = apparent viscosity, [cp] β = beta parameter as function of total well production (QT), water cut (Wc) and poral volume, [days] λ = derived rheological parameter, dimensionless ν = perforated interval (h) to drainage radius (Re) coefficient, dimensionless η = perforated interval (h) to mean poral radius (Dpmic), dimensionless ξ = wellbore radius (Rw) to drainage radius (Re) coefficient, dimensionless ζ = conventional to enhanced rheological parameter, dimensionless δ = conventional to enhanced rheological parameter, dimensionless ε = reservoir Microbial Migration Efficiency (RMME), dimensionless A,B,C,D = intermediate variables, dimensionless Bo = volume factor, [std m3/reservoir m3] Dpmic = mean poral throat diameter, [µm] DV = Delta Viscosity index EOR = EOR index etmv = derived rheological parameter, dimensionless etv = derived rheological parameter, dimensionless Factor = scale factor GOR = gas oil relationship, [m3/ m3] h(h) = effective interval, [m] K = absolute permeability, [md] Kh = horizontal permeability, [md] Kr = relative permeability, dimensionless Ktmv,Ktv = first Ostwald de Waele Nutting rheological parameters, after MEOR (Krmv) to conventional (Ktv), [cp.(1/s)(ntv-1)] Kv = vertical permeability, [md] L = effective lenght, horizontal well, [m] maxSR =maximum explored Shear Rate, [1/s] MEOR(ti ) = productivity index ratio, MEOR performance index, dimensionless = rotational to capillary geometry correction factor =minimun explored Shear Rate, [1/s] = Newtonian index = second Ostwald de Waele Nutting rheological parameters, after MEOR (ntmv) to conventional (ntv), dimensionless P = derived scaling group pwf = dynamic pressure before MEOR, [psi] pwfmeor = dynamic pressure after MEOR, [psi] Mf minSR NI ntmv,ntv

Pe = static reservoir pressure, [psi] Qmeor(ti ) = oil rate after MEOR, [m3]

Qo(ti ) = oil rate before MEOR, [m3] R(ti ) = migration radius at time ti , [m] RDie(ti ) = instantaneous migration radius at time ti to RDiw(ti )

drainage radius, dimensionless = instantaneous migration radius at time ti to

wellbore radius, dimensionless Re = drainage radius, [m] Rm = radius of microbial bioreactor (size of colonized zone) [m] Rw = wellbore radius, [m] Rwhoriz = equivalent wellbore radius, horizontal well, [m] Sirr = irreductible water saturation Sor = residual oil saturation SR = shear rate, [1/s] TMD = Temperature of Maximum Discrimination of rheological properties, [° F] V p = poral volume at drainage radius (Re), net pay (h) and porosity (Por), [m3] Vrest = restricted Microbial Migration Velocity, [m/day] Vfree = unrestricted Microbial Migration Velocity, [m/day]

Subscripts control = original sample condition (pre MEOR) e = natural logarithms base, 2.7172... h = horizontal. i = data point, spatial reference m = microbial enhanced max = maximum min = minimum o = original t = time v = vertical x = direction along well axis y = direction perpendicular to well axis

DIETRICH F.A., MAURE M.A, DIAZ V.A., ARGAÑARAZ H.

Equations

SPE 53715

R(t i ) = (1 − eVrest .t i ).Rm ..........................................(Eq. 17) Qmeor(ti )

MEOR(Ti ) =

Pe − Pwfmeor(ti ) Qo (ti )

.............................. (Eq. 1)

Pe − Pwf ( ti )

MEOR( ti ) =

A B(ti ) − C (ti ) .D.P.ζ .δ

........................... (Eq. 2)

L ..................................................................(Eq. 22) Re

Rw .(1 + ψ ) ........................................ (Eq. 5) 2

ξ=

h( h ) = h ψ ............................................................. (Eq. 6) A = 1 − ξ etv ............................................................. (Eq. 7) B(ti ) = 1 − ( RDie( ti ) )

C (ti ) = 1 − ( RDiw(ti ) )

D =ξ

etmv

P = (v.

δ =

h ..................................................................(Eq. 21) Re

η=

etv

2.h Dpmic.10 −6

Rdiw(ti ) = Rdie(ti ) =

R ( ti ) Rw R ( ti ) Re

.....................................................(Eq. 25)

......................................................(Eq. 26)

µ k = Ktv.( SRk ) ( ntv −1) .............................................(Eq. 27) ......................................... (Eq. 9)

λ = ntv − ntmv ......................................................(Eq. 28)

.............................................................. (Eq. 10)

etv = 1 − ntv ..........................................................(Eq. 29)

β ) λ ................................................ (Eq. 11) η. factor

etmv = 1 − ntmv .....................................................(Eq. 30)

Mf = (

Ktmv ........................................................... (Eq. 12) Ktv

1 − ntv ζ = ......................................................... (Eq. 13) 1 − ntmv 2.10 −6 Factor = ............................................ (Eq. 14) 24.3600.π

NI = (

3.ntmv + 1 ntmv ) ...........................................(Eq. 31) 4.ntmv ( µapp control ) min SR − ( µapp control ) max SR

( µapp

inoculated min SR

)

µappm α= .......................................................... (Eq. 15) µappo Vrest .............................................................. (Eq. 16) Vfree

− ( µapp

inoculated max SR

) TMD

)

...............................................................................(Eq. 32) max SR

∑

( µapp i ) control −

DV = ( i = min SR

ε=

...................................................(Eq. 23)

Rw .................................................................(Eq. 24) Re

............................................ (Eq. 8)

etmv

π .Por ................................................(Eq. 20) 4

Kh .................................................................. (Eq. 4) Kv

Rwhoriz =

Vp ..................................................(Eq. 19) QT .(1 − Wc )

Vp = h. Re 2

K h = K x .K y ....................................................... (Eq. 3)

ψ=

β=

max SR

∑ (µapp )

inoculated

i = min SR max SR

∑ (µapp )

) TMD

control

i = min SR

......................................................................................(Eq.33) EOR =

1 .....................................................(Eq. 34) 1 − DV

SPE 53715

MICROBIAL ENHANCED OIL RECOVERY PILOT TEST IN PIEDRAS COLORADAS FIELD, ARGENTINA