First Successful Deployment of Liner While Drilling Technology in Depleted Reservoir of Western Offshore India

Abstract The Mumbai High field in Western offshore of India presents major challenges to both drilling and liner running operations, because of reservoir being depleted and severe lost circulation conditions. Thus Liner while drilling, a new technology was deployed as a pilot Project to drill in these troublesome carbonate reservoir. The operator had previously experienced severe losses in the zone leading to big loss of rig days and damage to Reservoir due to LCM (Loss Circulation Materials) Pills. The liner while drilling service is a sustainable technology which combines 4.75in rotary steerable system BHA (Bottom Hole Assembly) with various logging tools, 8.75in hole opener/reamer, a mud motor, and a 7in liner with 8.5in reamer bit to help overcome the challenges while drilling in zones with low formation pressure and unstable formations. Running the liner while drilling helps maintain wellbore stability and reduces open hole exposure. It is also beneficial in reducing the time required by eliminating extra trips as the liner is installed at Target Depth in the first run. It is important to understand that Drilling with a mud motor and low RPM from surface is stressing the formation much less than conventional Rotary steerable BHA. Losses were contained with special mud additives. Plastering & smearing effect across the well bore added value in curing the Losses. This Technology Reduced formation damage by avoiding repeated LCM pills. Post Drilling, the inner string was Pulled out of hole leaving the liner at bottom which was later cemented with Cement Retainer. The technology proved to be Sustainable and with reduced HSE risk for the operator. The Paper will discuss in detail about the field of application, Prejob planning for Liner while Drilling Job, Onsite Execution and Successful completion of the well. This technology Successfully drilled, lowered, and Cemented 7in Liner at Target Depth saving rig time for the operator.