Application and Challenges of Pressured Mud Cap Drilling (PMCD) for Petrophysical Interpretation in Carbonate Reservoirs

Newfield Exploration Malaysia drilled a well in the Central Luconia Province offshore Sarawak and it is designated “Well-A” in this report. Well-A is a significant gas discovery with a 550 meter gas column in Cycle V carbonate reservoirs. The well is HPHT (High-Temperature & High Pressure) with a formation temperature of 270 degF and formation pressures ranging from 10,000 to 10,200 psi. The well was switched from conventional drilling to PMCD (Pressured Mud Cap Drilling) mode when a gas kick occurred at the top of carbonate. At the time of this report, it is the highest pressure well drilled using PMCD mode. During the PMCD drilling, sea-water was used as sacrificial mud and no cuttings were recovered to the surface. Due to the severe invasion of sea-water into the high porosity limestone in Well-A, no gas effect is observed on the density-neutron reading and resistivity value is suppressed.