Advanced Logging and Analysis Identified Thick Oil Zone Undetected by Basic LWD Measurements, Offshore Malaysia | Schlumberger
Case Study
Location
Malaysia, Asia, Offshore
Details

A Malaysian operator evaluated a potential pay zone with the FlairFlex advanced real-time logging and analysis service, correctly identifying oil and gas zones while drilling.

Products Used

Advanced Logging and Analysis Identified Thick Oil Zone Undetected by Basic LWD Measurements

Operator pinpoints best sampling depth in complex reservoir with real-time fluid logging and analysis service

The operator’s concerns

An operator was drilling a wildcat exploration well offshore Malaysia in a thickly stacked sandstone reservoir. The operation required as much formation evaluation information as possible without exceeding the allotted budget. Accurate while-drilling formation evaluation information would ensure potential pay zones were not overlooked and would subsequently help to optimize the wireline sampling program.

What Schlumberger recommended

Schlumberger suggested using the FlairFlex service to produce cost-effective and highly accurate formation evaluation information. The service quantifies hydrocarbons present in fluid returns at surface in real time, providing valuable downhole insight before downhole sampling or well testing operations are possible. This data adds confidence in reservoir evaluation interpretation and can be obtained independently from well conditions and with zero additional operational risk.

What was achieved

The FlairFlex service enabled the operator to identify a thick hydrocarbon zone using real-time analysis, which indicated that the zone contained a complex fluid distribution with intercalations of lighter and heavier hydrocarbons. Analysis from the FlairFlex service strongly indicated that this interval is a gas zone, whereas data from LWD was inconclusive.

The operator subsequently collected two downhole samples in a gas zone and one in a suspected oil zone. Analysis of the two shallower gas samples confirmed the fluid type. However, a fluid pumped from the suspected oil zone was identified as water, possibly Water-based mud (WBM) filtrate. Based on the FlairFlex service analysis suggesting the presence of liquid hydrocarbon, the operator decided to reset the wireline formation tester and begin pumping at a higher flow rate. This enabled oil to break through and the collection of high-quality samples. Later PVT analysis results matched the C1–C5 composition from the FlairFlex service.

Real-time analysis from FlairFlex service revealed an oil zone; PVT analysis showed strong agreement with the real-time fluid typing.
Real-time analysis from FlairFlex service revealed an oil zone; PVT analysis showed strong agreement with the real-time fluid typing.
Real-time analysis from FlairFlex service revealed an oil zone; PVT analysis showed strong agreement with the real-time fluid typing.
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At the first pumpout station, real-time downhole fluid analysis determined that only water, or possibly WBM, was pumped. Operator confidence in the fluid analysis from the FlairFlex service resulted in setting the wireline formation tester again to pump additional fluid. Oil breakthrough was observed, and the pay zone was extended to this interval.
Products Used

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