Geo-Stopping at the Top of Carbonate by Reducing the Depth Uncertainty using Seismic While Drilling, Near-Bit Gr, and Resistivity Real-Time Data, A Novel Carbonate Reservoir Entry Strategy in Deep Water Malaysia

Summary Seismic-While-Drilling and Near-bit logs were integrated to identify a high pressure ramp known to exist above the top carbonate (TOC) reservoir in an exploration well located offshore in deep-water Malaysia. It was critical to stop drilling the shallower section at the TOC to avoid the high-pressure ramp. The overburden shale of this section needed to be isolated with casing before drilling the carbonate section for safety. However, the seismic uncertainty of the TOC at the pre-drilling phase was large, and it was critical to identify the TOC confidently. Real Time SWD and near-bit log processing during drilling progressively built the accurate time-depth-velocity profile. VSP processed results were interpreted and extrapolated to predict the TOC depth with decreasing uncertainty in real-time. We were able to accurately identify the TOC depth 120 m above it. This case study demonstrates with careful planning and the use of an integrated approach a well in a high-pressure regime can be drilled safely with much reduced uncertainty.