For many of Asia Pacific low salinity medium to high porosity oil reservoirs, carbon-oxygen (C/O) logging has provided an effective method of through casing reservoir surveillance. This technology has been applied for well over two decades to provide saturation characterizations in conditions that are often challenging even in the openhole environment. To be successful, however, close attention must be paid to strict criteria during stages of problem identification, candidate review, well preparation, data acquisition, data processing and tool response interpretation.

A joint team was formed last year between operating company and service provider personnel. The charter of this group was to form standing best practices designed to optimize results from this technology. Case examples1  of interest related to this effort included:

  • comparison of calcium yields to the open-hole caliper in a washed-out borehole

  • C/O responses in an apparent extensive exterior borehole cavern that potentially was a result of formation sanding

  • time-lapse, post cement-squeeze, near-wellbore fluid displacement recovery observed with monitor logging runs

  • potential misinterpretation from log responses through an oil-filled cement sheath channel

  • inter-reservoir cross-flow flushing induced saturation distortion resulting in failure to evaluate true reservoir hydrocarbon volumetrics

  • estimation of reservoir saturation from within a hydrocarbon-rich borehole

  • effects of formation lithology on C/O log responses

  • using C/O to locate bypassed reserves in coning reservoirs

  • using C/O to monitor water and steam flood fields as an input to reservoir description modeling

  • economic gains realized from recent C/O log applications

This paper presents a short C/O technology overview, historical review of past practices, a review of joint discussions between team members providing and using the associated log application techniques and describes the ongoing Carbon-Oxygen Workshop Forum (COWF) review series. Additionally, some key C/O best practices developed from over 150 logging experiences in Indonesia are highlighted.

Keywords:
consideration, chuong nguyen spe 64405, successful carbon-oxygen log application, log application, gede adnyana, application, bekasap, cement, reservoir, spe 64405
Subjects:
Drilling Operations, Casing and Cementing, Well & Reservoir Surveillance and Monitoring, Reservoir Characterization, Improved and Enhanced Recovery, Reservoir Simulation, Formation Evaluation & Management, Reserves Evaluation, Information Management and Systems, Cement and bond evaluation
Copyright 2000, Society of Petroleum Engineers
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