Drilling Study Group - Increasing the Wellbore Pressure Containment in Gulf of Mexico HP/HT Wells
The presentation 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 with no success increasing the hole’s pressure containment.
The WPCI treatments raised the leakoff test (LOT) across the 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 treatments 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.1-4 This can then allow use of increased MWs and drilling pressures to prevent excessive gas influx from high-pressure sands without lost circulation (LC) in adjacent weak zones.
The presentation also 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 operations5 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.
16925 Northchase Drive
Houston , TX 77060