Carisito is an interesting area composed of five neighbor fields with a non so complex structure but an heterogeneous system of channels and bars, where it can be found from consolidated and tight sandstones to permeable ones (10 - 800 md), the porosity ranges from 8 to 15%. The whole area has a total of 168 wells which were drilled from the earlier riffles (1950's) to the middle eighties (1983's), in most of them water base mud was used. Total depths reached in the area go from 12000 to 15000 feet. There has been discovered 228 reservoirs so far.. The remaining oil in place is about 200 MMbls and 50% is contained in just 25 reservoirs. The average original well tests were about 1000 BOPD and nowadays, the last well tests are about 300 to 600 BOPD. This is one of the reasons why this area is an important place for reinterpretation and applications of additional recovery techniques. In this study it was possible to have special core tests from key wells in the area that allow us to determine a close relationship between the performance of the zone completed and the rock quality of the flow units and containers involved, regarding the type of oil and energy status of the reservoir. Since the main drive mechanism is gas in solution, it was necessary to classify the rocks by pore type and check how the water saturation changes with depth so we can compare and make a match between the rock quality of the different flow units and the performance of the sands with representative core and production data. This procedure generates a way of finding not only the best quality of the reservoirs but also typical bypassed pay zones in mature areas. Besides, based upon quality rock maps that were made by levels, it was possible to optimize the perforation intervals and improve new well locations recommendations for infill and outstep drilling.

AAPG Search and Discovery Article #90937©1998 AAPG Annual Convention and Exhibition, Salt Lake City, Utah