Bulletin of the Geological Society of Malaysia, Volume 43, Dec. 1999, pp. 377 – 384
1Schlumberger East Asia, Kuala Lumpur, Malaysia
2VICO, Jakarta, Indonesia
3Santa Fe, Jakarta, Indonesia
4CPOC, Kuala Lumpur, Malaysia
Abstract: With technical advances in surface seismic and downhole electrical imaging techniques, it is now possible to not only map the distribution of reservoir sandstones in the subsurface, but to more accurately define the orientation of productive fairways , or “sweet-spots”, within the sequence.
This paper will summarize the results of four case studies of how channel sands, laid down in different depositional settings, have been recognized with borehole electrical imaging. From sedimentary features and palaeocurrent directions within the sands it has been possible to determine their orientation. These channel sands frequently have favorable reservoir characteristics; having often been laid down in higher energy settings, they commonly have coarser and better sorted grains, less clay and improved poroperm characteristics. However, they often have limited lateral extent and shoe-string geometries which makes them more difficult to predict in the subsurface. The ability to locate wells along prospective trends can result in the drilling of thicker pay zones, and in significantly improving the ratio of good producers to dry or poorly producing wells.