Schlumberger

Case Study: Three Record Runs Achieve High of 95% Net Pay in Compartmentalized Reservoir

Geosteering saves USD 10 million on complex deepwater development offshore Angola

Challenge: Maximize production from long horizontal wells drilled through soft, unstable formations in compartmentalized reservoirs.

Solution: Use PowerDrive Xceed RSS for harsh, rugged environments in combination with PeriScope bed boundary mapper, EcoScope multifunction logging-while-drilling service, StethoScope formation pressure-while-drilling (FPWD) service, and TeleScope high-speed telemetry-while-drilling service for productive drilling.

Result: Helped save USD 10 million on complex, deepwater project; Achieved 80% average net pay from the three longest horizontal drainholes drilled in Angola; Ran 4,680 m of completion screens—with no NPT.

Meet production goals

An operator planned to drill four water injection wells and three horizontal production wells in Gimboa field, offshore Angola. Data acquired in the injector wells indicated that the target reservoirs in this complex deepwater development were compartmentalized by permeability barriers, which made placement of the horizontal wells to meet the operator’s production goals challenging. The objectives were to minimize unproductive intervals, cross as many intrareservoir barriers as possible, confirm connectivity to injector wells, and deliver a smooth borehole profile that would allow running of completion screens.

Avoid exiting the reservoir

All those objectives were met by using a PowerDrive Xceed RSS for harsh, rugged environments to provide directional control in the weak, unstable formations and Schlumberger real-time LWD and MWD services to deliver information for geosteering and formation evaluation. Distance-to-boundary measurements for estimating shoulder-bed resistivity—made with a PeriScope bed boundary mapper—enabled the drilling team to differentiate between intrareservoir shales that had to be penetrated and boundary shales that had to be avoided, and to make the necessary trajectory changes.

These PeriScope measurements were transmitted to the surface by the TeleScope high-speed telemetry-while-drilling service, along with data from EcoScope multifunction LWD and StethoScope FPWD services. The EcoScope data—acquired close to the bit before washout occurred—was used for both geosteering and formation evaluation, and the StethoScope pressure measurements confirmed communication between the injector wells and the producing wells.

Put wells in best place

Use of PowerDrive Xceed RSS, PeriScope, EcoScope, StethoScope, and TeleScope services to put three horizontal production wells in the best place in the compartmentalized reservoirs helped save USD 10 million on the complex deepwater development. Net pay was as high as 95% and averaged 80%. Although the wells were the longest horizontal drainholes that had been drilled in Angola—and had many trajectory changes—their smooth profiles enabled installation of 4,680 m of completion screens with no NPT.


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Three Record Runs Achieve High of 95% Net Pay in Compartmentalized Reservoir
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