Cover: Oilfield Review Spring 2002
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Depth imaging, once too costly and difficult for commercial use, is now the preferred seismic imaging tool for todayâs most challenging exploration and reservoir-delineation projects. In structurally complex areas, especially where faulting and salt intrusions lead to complicated seismic-velocity models, traditional time-domain processing gives misleading results; only depth imaging reveals the true location and shape of subsurface features. This article shows how depth imaging improves seismic images and presents examples demonstrating how oil and gas companies use it to improve their success rates.
Oriented perforating improves hydraulic fracturing and facilitates screenless completions that prevent sand influx. A new wireline tool orients guns so perforations align with the preferred fracture plane and most stable direction in a formation, or intersect natural fractures for better productivity. This technique also is used to shoot the high side of horizontal wells, prevent damage to well-completion components, repair channels in cement behind casing, establish communication with relief wells and avoid casing collapse.
During drilling, not knowing the location of the bit relative to surface seismic reflections adds risk and cost to operations. Crucial updates on reservoir-target and drilling-hazard depths can now be made reliably without interrupting the drilling process. This article introduces a new logging-while-drilling tool that accomplishes this by providing check-shot information in real time, without the limitations of earlier techniques. The tool produces high-quality seismic images after processing and, with proper planning and advancements in telemetry systems and processing software, holds great potential for real-time seismic imaging.
A new cased-hole testing tool drills through casing, cement and reservoir rocks to measure pressures and collect fluid samples. Unlike other casedhole testing devices, this tool plugs the holes it drills to isolate the formation from the wellbore after testing. This sealing capability allows operators to resume production without costly casing or cement repairs.
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