THE SANDS OF BRINE F
ar from the mythical Sandman of folklore who brings pleasant sleep and sublime dreams, sand production in oil and gas operations is an all-too-real nightmare that seems to intensify with every improvement in production technique. Finding novel ways to squeeze more hydrocarbons from the formation invariably entails producing not only more water but also more sand – in many cases, a lot more. Not only are sands of finer grain size being used as proppant (further complicating its capture and removal), producers are encountering increasing volumes of sand as operations tap into an ever greater number of ‘soft’ formations, especially in gas fields. And as the demand for natural gas continues to soar with the shift away from coal and other trends, the volumes of sand will naturally track with that upward demand.
Costly geophysics
Sand in the flow stream may be an old problem, but it remains as serious as ever, and it is just as ‘scalable’ as the best modular equipment. Sand can inflict tremendous harm on everything in the wellbore: from the smallest section of tubing to the casing, all the way up to surface equipment and downstream production facilities. It can even compromise wellbore stability and prematurely end the life of a well. If sand-blasting with only moderate pressures can
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remove layers of rust from metal and carve lines in concrete, imagine what it can do at the high pressures found in wells. Moreover, the problem is not confined to this or that basin – it is global and prevalent in Africa, North America, South America, Southeast Asia and other regions, both onshore and offshore, particularly in gas fields where reservoir formations are unconsolidated or semi-consolidated. High-flowrate gas wells are especially prone to damaging levels of sand production, where the elevated flow and turbulence exerts drag on the formation, thereby dislodging ever more sand particles, which are then accelerated to erosive velocities that wreak even more havoc on operational infrastructure. Much more than a mere inconvenience, the damage wrought by sand continues to cost companies millions of US dollars every year.
Hydrocyclones: not just spin
Fortunately, and despite the headwinds, the same industry that has for some 170 years fuelled modern living and economic growth continues its long-held tradition of pioneering innovation. Just as recycling flowback and produced water continues to evolve and become the norm, the removal of sand from the flow stream has advanced dramatically in just the past few years.
