The dual-anchor technique developed by SLB can diagnose the root cause of valve failures, recover the functionality of a stuck flow tube, and then lock out the flow tube in the same run. The method can be used on any safety valve without requiring a customized mechanical lockout tool. The ReSOLVE™ instrumented wireline service provides real-time quality control of the process and reduces the need for subsequent runs through the valve.
An offshore operator in a South American gas field found a well obstructed by a surface-controlled subsea safety valve (SCSSSV) that was stuck in a partially open position, deferring production at the well. A slickline mechanical intervention was tried but failed to lock the valve properly.
SLB Reservoir Performance experts recommended the ReSOLVE instrumented wireline intervention service. Instead of using a costly workover to change the tubing and valve, the ReSOLVE anchor-linear actuator could be used to exercise the flow tube and then lock out the valve. In this case, the anchor-linear actuator would be modified to include an additional anchor to provide more traction, as well as a dimpling capability.
The first attempt used the anchor-linear actuator to exercise the flow tube—stroking up and down five times. This step was followed by a positive pressure test of the flapper with the flow tube retracted. However, opening and closing the valve using a surface control line pressure cycle was not successful.
Next, the dual-anchor method was used to exercise and dimple the flow tube in the open position. The top anchor provided a fixed point in the tubing where the linear actuator could extend or retract to exercise the flow tube while measuring the displacement and applied forces. The bottom anchor was used to transmit an axial force and dimple or deform the flow tube, to lock it out without pulling out of hole.
The bottom anchor was applied with a force of 26,000 lbf, with deformation observed after 20,000 lbf. At that point, the sleeve locked in place with the flapper permanently opened. A subsequent run through the valve proved the effectiveness of the lockout.
The real-time instrumentation and displacement of the anchor-linear actuator played a key role, providing a mechanical response when increasing or decreasing the control line pressure and generating a signal when exercising each stroke, to highlight the impact of the process and confirm the full travel of the flow tube prior to dimpling it.
This novel technique developed by SLB can diagnose the root cause of a failure in real time, recover the functionality of a stuck flow tube, and then lock out the flow tube in the same run. The method can be used on any safety valve without mobilizing a custom mechanical lockout tool. The instrumentation of the ReSOLVE service provides real-time quality control of the process and reduces the need for subsequent runs through the valve.
