Abstract
Abstract
Following the rig-based well testing stage, completion programs of high-pressure wells in North Kuwait call for well killing with heavy oil-based mud (OBM). The workover rig is then demobilized, and production flowlines are installed. Well activation plans are carried out riglessly, and coiled tubing (CT) is instrumental to bringing the wells back to sustainable production. One of the major drawbacks from this practice is the formation damage generated by the OBM, which often requires additional interventions for remediation.
To address this limitation, a new approach leveraging instrumented CT for temporary well suspension was recently implemented. Real-time downhole telemetry is enabled by an optical line installed in the CT pipe and used to accurately set a through-tubing inflatable packer (TTIP). Once the latter is anchored at the planned depth, above the interval open to the formation, CT is disconnected from the packer assembly, and the fishing neck is protected with a sand plug. CT is then retrieved to surface, and a slickline dump bailer is run to spot cement on top of the sand plug. Once the cement has set, CT is run to displace the wellbore to kill fluid.
Two pilot wells were selected to implement this new approach for temporary well suspension. Both wells had a maximum potential wellhead pressure in the order of 7,400 psi, and 15.0-ppg OBM was originally planned for well suspension purposes. Upon completion of the zonal testing program - which included initial stimulation, well activation, and flowback - instrumented CT was run with high-pressure rotary jetting to condition the TTIP setting depth and displace the wellbore with brine, after which, a shut-in wellhead pressure near 2,000 psi was observed. In the next CT run, TTIP was set close to the end of the production tubing, and critical stages, such as depth correlation, packer inflation, and packer anchoring testing were closely controlled via real-time downhole measurements. Additional verification of the TTIP effective seal was carried out before the CT was disconnected from the packer assembly through an inflow test relying on live downhole pressure monitoring. Once the TTIP released, the temporary suspension was completed following the methodology described above. Finally, the wells were observed at surface with zero pressure for more than 24 hours, receiving acceptance from the operator.
This alternative approach for temporary well suspension represents an innovative solution to bring wells back into production without additional restimulation or well activation. This methodology greatly relies on CT real-time downhole telemetry, and operators from the Middle East can benefit from the experience gained in this project.