OTC 2021: Real-time Wireless Depth Correlation Without Intervention

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Editor's note: This article appears in the special OTC edition of the E&P newsletter. Subscribe here.

Correlation of tool depth has long been done using pipe tally. Many of us have likely observed the scene with multiple people reviewing their individual tally books and calculations. Finally, after debate, a supervisor makes the call on which tally to use.

The accuracy of depth measurement improved with wireline correlation using PIP tags. This has been the standard for depth correlation used for packer setting depth and tubing-conveyed perforating (TCP) gun depth and provides an accurate position, but it is time-consuming and is not always feasible in deep water or highly deviated wellbores. If the bottomhole assembly (BHA) must be moved to position tools on depth after correlation, a second wireline run is required to confirm the tools were moved to the correct depth.

Eliminating uncertainty, saving rig time

Halliburton's DynaTrac real-time wireless depth correlation system, released in 2020, provides a new technology that enables operators to accurately position packers, perforating guns and the BHA without running wireline or moving the work string to reduce uncertainty and save rig time. The system increases efficiency during operations that require accurate BHA depth or on-demand positioning throughout operations, eliminating uncertainty in tool position without the need for wireline or work string manipulation. 

Operating as a downhole ruler using an array of sensors to detect gamma signature with position resolution less than 1 ft, a simple click of a button in the software retrieves the BHA position immediately. This on-demand measurement allows operators to correlate position of packers and TCP guns without wireline intervention or work string manipulation, saving numerous hours of valuable rig time.

Similar to traditional correlation techniques, DynaTrac senses gamma signature as a reference. Unlike traditional systems that use a single sensor that can determine position at a single instance of time, DynaTrac’s array of sensors provide a completely static measurement that allow continuous tracking of position throughout operations. Since the system provides a static measurement, position can be confirmed after the packer is set.

The multisensor real-time capabilities of the system allow tracking of tool position throughout job operations. There are many examples of operations where knowledge of sensor or tool position provides improved reservoir understanding or increases efficiency of operations. One such example is in tracking position of gravel pack service tool as it is shifted from run in hole to pumping frac fluids to reversing out post-frac.

Knowledge of the position throughout these operations helps eliminate uncertainty, increase efficiency, and make faster and more informed decisions. Formerly, knowledge of the service tool position could only be inferred from rig sensors of weight and hook height. Pipe stretch, buoyancy, friction and thermal effects, among other factors, each contribute to uncertainty when making these inferences in position. Uncertainty in the position of the service tool can lead to costly inefficiencies or additional well operations. The real-time position measurement provided by the DynaTrac system eliminates these uncertainties, using a direct position measurement and transmitting via wireless acoustic telemetry.

Conclusion

Accurate packer setting depth and TCP gun depth have long been of primary importance in well operations. Proper placement of charges and subsequent completions are critical to ultimate recovery. Traditional methods to correlate position of these assemblies downhole using wireline or work string manipulation are time-consuming and carry operational risks. DynaTrac provides accurate position measurement for proper packer setting depth. In addition, the system is delivering new insights into gravel pack operations and assurances previously not available.