WPCI Treatments in a Deep HP/HT Production Hole Increase LOT Pressures To Drill Ahead to TD in a Gulf of Mexico Shelf Well

摘要

This paper covers two wellbore pressure-containment integrity (WPCI) treatments that substantially increased the pressure- containment integrity in 852 ft of open hole in the last sidetrack for the production hole section. This ultimately saved having to set pipe early, which could have jeopardized the commercial discovery of a lower gas sand. Earlier side tracks attempted unsuccessfully to bypass the loss/flow problems that would not allow drilling ahead and increasing the 18.0-lb/gal mud weight (MW) to drill into a high-pressure zone on a deep, high-pressure/high-temperature (HPHT) well in the western Gulf of Mexico shelf offshore Louisiana. Various lost-circulation material (LCM) treatments were used ith no success increasing the hole’s pressure containment. The WPCI treatments raised the leakoff test (LOT) acrossthe entire 852 ft of open hole up to 19.1 lb/gal equivalent ppge) vs. the lower LOT of 18.3 ppge before the first WPCI job. LOTs were performed before and after each of the two WPCI treatme nts to measure improvement in the hole’s pressure-containment integrity. This LOT data helped prove that apparent fracture gradients can be simultaneously increased in multiple numbers of layers and different types of weak formations exposed in long, open holes by inducing near-wellbore, flexible stress cages created from WPCI treatments. This can then allow use of increased MWs and drilling pressures to prevent excessive gas influx from high- ressure sands without lost circulation (LC) in adjacent weak zones. The paper discusses the WPCI treatment design and job procedures, including treatment optimization by the analysis of data from openhole wireline/logging while drilling (OHWL/LWD) logs, cuttings lithology, fracture-seal location indicators (torque on bit [TOB]/weight on bit [WOB]), and before/after LOT pressures. Real-time operations also described allowed remote expert analysis and support for wellsite personnel to (1) interpret formation characteristics for optimized treatment design and ( 2) analyze treatment pressure/rate data for selected placement of WPCI sealants.