Petrophysical Study and Formation Evaluation of Jake Reservoir, Block 6, Muglad Basin, Sudan

Abstract

The study area (Jake oilfield) is located on the Western Escarpment of the Fula Sub-basin of the Muglad Basin, which is bounded by the latitudes 11°20' and 11°36′ N and longitudes 28° 30′ and 29° 36′ E. This oilfield has been structurally subdivided into three main structures of Jake, Jake Central and Jake South. The goal of this study is to identify and to interpret the reservoir quality and properties (lithology, porosity, shale volume, and water saturation) and then to detremine sand continuity of Bentiu formation, to achieve this goal in successful way the information and data of three wells (Jake South -2, Jake South -3, Jake South -15) were made available, then the evaluation of the given data has been processed using the interactive petrophysic software (IP 3.6) version. The wireline logging and mud logging data had been carefully evaluated during the process of the data application, and data quality was thought to be good. Eventually, the results obtained using the shaly sand evaluation techniques, were in better agreement with core and test data. For the Reservoir and shale identification the most useful indicator was obtained from the behavior of the density and neutron logs. The neutron – density cross plot is the best method for lithology identification. Density – Neutron cross plot values had been used to identify the pure matrix and/related porosity, v-shale, porosity and water saturation models had been done and full interpreted from the initial results cut off parameters also determined and multi targets prospects of all wells had been marked, beside net-reservoir and net-pay had been obtained successfully.In Jake South -2 (the maximum net pay thickness for Bentiu reservoirs is 48.2m and the minimum thickness is 3.66m, the average effective porosity is 17%, and the average water saturation is 48%), in Jake South -3 (the maximum net pay thickness for Bentiu reservoirs is 4.72m), the average porosity is 22%, and average water saturation is 86%). Hence in Jake South -15 (the maximum net pay thickness for Bentiu reservoirs is 28.12m, the minimum thickness is 4.5m, the average porosity is 18% and the average water saturation is 33%)