New Approach in Conducting Fault Seal Analysis: Case Study of Northwest Java Basin, Indonesia

Abstract

Fault seal analysis (FSA) become one of the most important task to conduct in oil and gas industry particularly in relation to risk and reservoir compartmentalization. However, the method for conducting such analysis is limited and often challenging due to lack of data and complexity in local geological setting. For example, standard FSA workflow using Shale Gouge Ration (SGR) algorithm doesn't works in field with majority carbonate sequences. Key elements in conducting FSA is to determine SGR using v-shale contents in rocks sequences which involve in the faulting process. In general, this method only works effectively in clastic sedimentary sequences. This is argued because of method in determining v-shale value where commonly determined using Gamma Ray (GR) log which is not good representation of clay contents in limestone. In this study, we evaluate three different petrophysical approach mainly GR, deterministic and probabilistic (Multimineral). All methods was compared and evaluated with well test result to determine sealing and leaking behavior. Study area is located in the Rengasdengklok field as part of Northwest Java Basin. The field produced from both clastic and carbonate sequences. FSA was conducted using 3D seismic and wire logs from 95 wells. The results show SGR value calculated using probabilistic method are less than other two methods which in general more representative due to high carbonate contents in most of rocks units. In turn FSA show that faults are tend to more sealing (using SGR cutoff 15% - 25%) than predictive before which generally more inline with some of the field evidence. Overall, this study concluded for carbonate sequences FSA must be done using probabilistic petrophysical approach particularly in determining v-shale/v-clay contents of the rock units.

AAPG Datapages/Search and Discovery Article #90291 ©2017 AAPG Annual Convention and Exhibition, Houston, Texas, April 2-5, 2017