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Mulcahy, Matthew1, Tanwi Basu1, A. Wahid Musbah2, Gavin Douglas1, Howard D. Johnson2, Kamarolzaman B. Yahya2, Mustafa Suleiman2 
(1) Schlumberger, Kuala Lumpur, Malaysia 
(2) Petronas Carigali Sdn Bhd, Kuala Lumpur, Malaysia

ABSTRACT: New Life for Old Data: Brown Field Reservoir Characterization and 3D Geological Modeling from the West Baram Delta Province, Offshore Sarawak, Malaysia

Field development studies on the Bokor and Betty fields have created facies based 3D geological models to appraise remaining reserves and determine strategies for economic redevelopment. This paper describes the reservoir characterisation and modeling workflow and highlights lessons learnt for similar re-development projects in the future. 
Since their discovery in the 1970's, extensive subsurface data, including core, well log, dipmeter, seismic and production data have been used to evaluate these Late Miocene coastal/deltaic reservoirs. However, previously these data had only been evaluated in 2D map form and had never been subject to a modern 3D geological modeling analysis. To do this, and to supplement the existing data, further in-depth studies were performed, including (1) petrography (SEM and XRD analyses) to determine framework grain and clay mineralogy, (2) facies analysis of core and well logs to generate electrofacies models, and (3) rock fabric/texture analysis from high-resolution dipmeter data to assess fine-scale heterogeneities. 
A key approach was the development of electrofacies models that integrate data at both the core and wireline log scale. Together with analysis of well log patterns and seismic amplitudes, this provided additional insight into the depositional setting and architecture of these multiple stacked (100s-1000s ft thick) wave- and tide-influenced coastal reservoirs. Propagation of the electrofacies within the geocellular models, combined with the additional geological understanding of the reservoirs, has significantly enhanced re-development decisions. 
Together with advancement in software and geological modeling techniques, these studies highlight the additional value that can be gained from existing and sometimes apparently neglected data.

 

AAPG Search and Discovery Article #90026©2004 AAPG Annual Meeting, Dallas, Texas, April 18-21, 2004.