The future of downhole fishing is digital

Fishing operations can be complex, and the basic nature of traditional fishing tools means that up until now such tasks have been performed somewhat ‘blind’ by oil & gas operators and service companies, an approach which runs the risk of turning any fishing job into a timeconsuming saga. Now, the award-winning Wellgrab ERFT has finally brought the oft-reviled challenge of downhole fishing into the digital age, using more than just ones and zeros to do so.

Fishing operations often require the application of great force downhole to retrieve hardware or tools that have been unintentionally lost or stuck downhole. With an inherent lack of sophistication characterizing many traditional fishing solutions, and the diminishing assistance of gravity in horizontal wells, two problems became more prominent in deeper and extended reach situations: getting to the fish, and recovering items without compounding the issue.

With the prominence of conveyance platforms like the Well Tractor, half the problem was solved, as the e-line deployed solution easily overcomes the limitations of traditional operations in highly deviated wells by driving tools to any target depth. However, traditional pulling and fishing tools were created for vertical use, or fully mechanical applications, leaving the need for a reliable tool to engage with the fish at the business end of the toolstring. Another shortcoming of traditional tools is that they often rely on any force applied at surface to be successfully transmitted to the desired point downhole – a task that becomes increasingly difficult, if not impossible, with increasing well deviation.

Filling the digital gap

With the entire operation of the oilfield now digital, operators can communicate with all their tools except fishing tools, creating the juxtaposition of having invested in digital equipment yet still depending on +50-year-old technology with low-level feedback, meaning almost full reliance on the experience of crew when it comes to retrieving lost or stuck items.

Operating on e-line, the Wellgrab ERFT (Electric Release Fishing Tool) resolves this issue by utilizing a range of external and internal grapples to match the specific requirement of engaging a downhole fish. Communication with the grapple is supported by a system measuring multiple parameters, all integrated with an actuation device such as Welltec’s 100K Well Stroker which is capable of delivering up to 100,000 lbs of force directly where it’s needed – downhole at the exact fishing point. Most traditional tools would be ripped apart under such force, making this solution a first for the oil & gas industry. These features have proven to be highly beneficial in the field, proving in one case that an available engagement length of just 29mm was sufficient to retrieve a parted toolstring (with a stuck mill bit) via 33,000 lbs of force. In situations like this it’s all about optimization, with real-time information on tool performance greatly enhancing operations, enabling tasks to be completed more quickly and efficiently than by conventional means.

The solution is not a single tool per se, it’s more like a platform for multiple tools, creating a single solution akin to that of a Swiss Army Knife with multiple applications. All that is required is to change the grapple at the end of the tool, and this includes plug setting/retrieval options.

ERFT – a failsafe approach

As the ultimate failsafe, a release-on-command electrical signal can be sent to the grapple at any time. In the unlikely event that the signal is lost, and it is not possible to send the release command, the battery back-up system is activated. At this point, an inbuilt timer starts a countdown and after a predetermined period – if connection is not re-established – this will issue a command to release the fish. The novel ERFT system provides full control over the ability to release and makes it practically impossible to get stuck or add more fish.

Wellgrab ERFT has a bidirectional motor, and when this is run in a standard manner it is in a passive mode. The bidirectional capability enables the development of new methodologies and new tools where the motor is utilized to actually engage the fish. In this manner, there is a wealth of feedback available such as power consumption, and millimetre precision with regards to the positioning of the motor. It is also possible to monitor parameters such as temperature, and movements or vibrations via an inbuilt accelerometer.

In the field

Initial toolsets have been placed for availability in the North Sea area, where the solution has overcome multiple complexities such as wellbore fill, deviation, and alignment of fish to complete fishing operations that would not otherwise have been possible on e-line. With this early success and proof of concept in the field, collaborators Autentik and Welltec are implementing plans for wider availability of toolsets, starting with Scandinavia and North America.

Operators might ask themselves ‘What have we got to lose...except our tools?’