In offshore China, high-pressure (HP) gas reservoirs have become primary exploration and production targets, characterized by pressure coefficients reaching up to 2.30 and extremely narrow safe-mud-weight windows. Globally, multiple successful field applications have demonstrated the effectiveness of electromagnetic look-ahead (EMLA) services for addressing these critical challenges while drilling by providing an accurate formation profile ahead of the bit to optimize geostopping efficiency.
Introduction
The Y Basin, a significant high-pressure, high-temperature (HP/HT) hydrocarbon-bearing basin in the South China Sea, has become a key focus for China’s oil and gas exploration.
In Block L, the target reservoir exhibits typical HP/HT characteristics, with a static formation temperature of approximately 200°C and a formation pressure coefficient as high as 2.30. The overlying shale layer has a lower pressure coefficient (1.80 to 1.90), creating a sharp contrast with the reservoir. This necessitates drilling in separate wellbore sections to isolate the shale from the reservoir. The transition between sections must be positioned as close as possible to the reservoir without penetrating it.
