--> Multidisciplinary Approach in Tight Oil Appraisal: A Case Study From Barmer Basin

2018 AAPG International Conference and Exhibition

Datapages, Inc.Print this page

Multidisciplinary Approach in Tight Oil Appraisal: A Case Study From Barmer Basin

Abstract

Despite a difficult era of low crude oil prices, productions from tight oil and gas fields have gained importance to meet the ever rising energy demands in developing nations. Barmer basin, a 300km intra-cratonic rift in NW India, has produced ~ 400 million barrels of oil since 2009. With the present production primarily from the multidarcy reservoirs on decline, prudent and cost-effective exploitation of tight oil and gas portfolio assumes utmost significance in order to maintain the reserve replacement ratio of this mature basin and augment the production shortfall. The exploration and appraisal activity within the basin is presently focused on tight rocks, wherein the lacustrine porcellanites facies within Barmer Hill (BH) Formation contribute significant share in terms of in-place resources. The reservoir rocks are thinly laminated siliceous units of medium to high porosity, low permeability and require hydraulic fracturing to produce at commercial rates. The Diatomite Play field, discovered to the north of the giant multidarcy Mangala oil field, hosts such porcellanite reservoir rocks of BH Formation in a tilted fault closure. Downdip exploration well tested commercial oil flow on hydraulic fracturing. However, one of three updip appraisal wells drilled on the eastern edge of the field produced mostly water with only 5% oil cut. The ambiguous appraisal results warranted further studies. Re-interpretation of petrophysics showed dissimilarities in saturation height trends in the exploration and appraisal wells which is also supported by reservoir pressure data acquired in these wells. These observations were integrated with the newly acquired 3D PSDM interpretation to infer faults, hitherto unidentifiable. Integrated interpretation showed the four wells drilled so far to be in separate fault compartments. On close observations, the water producing well is inferred to be connected to distal sands of deltaic facies towards east. Alternatively, the porcellaintes getting connected to underlying water bearing Fatehgarh Formation through a sub-seismic fault is also a distinct possibility. All observations are integrated in a stochastic model to optimize the future appraisal and development plans. A quick swab test conducted in one of the updip appraisal well confirmed presence of mobile oil. The paper stresses on the importance of innovative and pragmatic integrated multi-disciplinary approach for appraisal and subsequent monetization of such tight oil fields.