Publications

Carigali Hess Operating Company is currently developing and producing from four fields in Block A-18 within the Malaysian Thailand Joint Development Area (MTJDA). Located in the North Malay Basin the Cakerawala, Bumi, Bulan and Suriya fields have a number of technical challenges. These include complex geology associated with thick intervals of stacked pay, complex fluvial to marginal marine depositional setting and significant reservoir heterogeneity. Low resistivity low contrast (LRLC) intervals are an important subset of the Block A-18 reservoirs which until recently were poorly understood. They are volumetrically significant (10-40% of GIIP), hence there is an incentive to understand them fully. An integrated multidisciplinary approach was used to identify these reservoirs in the wells, define their lateral distribution, their reservoir properties and potential deliverability. Although most reservoirs in the Block A-18 are defined using conventional petrophysical approaches, LRLC reservoirs are common in the shallow section (Sequence I-II, equivalent to EPIC regional stratigraphy Group D, Madon et al. 1999). These reservoirs are usually fine grain (sands and silts), clay-rich and heterolithic. They are often bioturbated or laminated and grade into each other and conventional reservoirs vertically and laterally. As part of the Block A-18 field development, a comprehensive data acquisition program was employed resulting in a orld class subsurface database. Modern log suites from 60 wells, approximately 1792 feet of core, detailed sedimentological analysis, image analysis, petrology and extensive test data are available. Using these data, a holistic multidisciplinary approach was adopted to fully understand the depositional setting, distribution, sedimentological characteristics, key depofacies/lithofacies, the pore system and controls on reservoir quality. These were tied in with petrophysical analysis in order to understand the log response in various low resistivity low contrast lithofacies, and to define log cut-offs. In addition, a study of potential deliverability was carried out through analysis of mini-DST and dual packer MDT data. Analysis of test data, together with PLT interpretations from comingled test intervals, has been used to validate the petrophysical cut-offs required to define net pay. This study helped characterize reservoir intervals more accurately and the results will be incorporated into reservoir models to facilitate reserve estimates and optimize field development and management.