Operator Optimizes Drilling Performance, Successfully Reaching Total Depth with SonicScope 825 Service | Schlumberger
Case Study
Asia, Offshore

Challenge: Acquire high-quality sonic measurements while drilling an HPHT well with high shock and vibration; evaluate geomechanics in real time to manage drilling risks

Solution: Use SonicScope 825 multipole sonic-whiledrilling service to deliver robust real-time and memory sonic data, including downhole slowness-time-coherence data, for real-time data quality control

Results: Acquired excellent match between real-time and memory compressional and shear slowness in high stick and slip environment; accurately evaluated high-porosity gas formation despite mud invasion; successfully reached total well depth with geomechanics analysis

Products Used

Operator Optimizes Drilling Performance, Successfully Reaching Total Depth with SonicScope 825 Service

LWD service supports critical geomechanic analysis in South China Sea, reducing drilling risks in the HPHT environment

Facing challenges in South China Sea high-pressure, high-temperature wells

An operator drilling offshore South China Sea encountered many challenges during the exploration and evaluation stages. The two main issues involved the narrow mud weight window and the presence of a high-pressure formation. The need for high-quality logging-while-drilling (LWD) sonic measurements was critical to managing the overall risks of the drilling operations.

Acquiring high-quality sonic data for accurate real-time geomechanic analysis

Geomechanic research is performed before drilling the well to reduce the associated drilling risks and save rig time. Reliable, real-time sonic data is an integral part of the evaluation. Information from offset wells is compared with surface seismic data, and a good match between the two reduces uncertainty and boosts the confidence of operators.

Reached total depth with reduced risk

Using SonicScope 825 service, the operator obtained reliable LWD sonic data for both real time and memory. The real-time slowness acquired matched the memory data, and the time-lapsed logging measurement helped quantify the impact of mud invasion in the high-porosity formations, as a reduced slowness was acquired in the gas zone. This data helped the operator successfully reach total depth with reduced risk and uncertainty. Having proven success after first-time use of the service, the operator has decided to run the latest LWD sonic service in both 14 3/4-in and 12 1/2-in hole sections in future HPHT deepwater wells.

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Real-time data aqcuired is an excellent match with memory sonic data in shallow unconsolidated section.
“Schlumberger’s latest LWD sonic service provides high-quality real-time and memory data that can meet our timely decision requirements for exploration wells."

Chief logging engineer, Operator, South China Sea

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