Thinly Bedded Reservoir Evaluation Using High Resolution Mineralogical Based Lithofacies
Accurate quantification of low resistivity pay is a challenge in Disouq field due to the limitation of conventional open-hole log vertical resolution. In the well NWSG 7-1, thin beds detection, pressure points selection and sidewall core depth identification depended on detailed high resolution lithofacies output from iCore® processing results. The detailed high resolution lithofacies prediction combines the mineralogical composition of Elemental Capture Spectroscopy with the high resolution sampling rate of the Formation Micro Imager to derive its output; iCore. In iCore module, the mineralogical output of the elemental capture spectroscopy with coarse resolution 18″ can be divided into the thirteen lithofacies of iCore ternary diagram. The lithofacies distribution is used to define the reservoir pressure points, fluid sample points as well as sidewall core depths as though there is a complete core-based lithofacies description. In addition, lithofacies-based sand count is useful especially in the low resistivity pay zones; these counted sand layers increase the accuracy of reservoir estimation. In the results plot, the iCore output displayed beside the borehole images shows harmonious results. The success of reservoir pressure points, fluid samples and sidewall core selection was 85 to 90%. The integration between the petrophysical evaluation outputs with geological evaluation results within a quick turnaround period was the key to success in this case. Three samples of gas and one oil were retrieved and 95% of the sidewall core plugs were sandstone.
AAPG Datapages/Search and Discovery Article #90215 © 2015 Pacific Section AAPG Convention, Oxnard, California, May 3-6, 2015