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Understanding Trap Mechanism and Enhancing Oil Production by Integration of Seismic Methods — “A Multidisciplinary Approach” (A Case Study of Dabka Field)

Rajendra P. Sharma
Ankleshwar Asset, OIl & Natural Gas corporation, Ankleshwar, India

Exploration/ development planning is an integral part of reservoir management and aims at maximizing the value of producing property, and its success depends on the integrated model created by combining the ideas of Geologists, Geophysicists, Reservoir Engineers and Production Engineers. Integration of deep seismic studies will play a key role in this area, to get the exact spatial location on seismic data, including various factors affecting drilling, the right target depth, in right direction. Assets have sufficient well, petrophysical, reservoir and production data and integrating with the available seismic methods, it help in understanding the geological complexities and in turn in enhancing production and even in extending the asset boundaries.

This paper demonstrates the effectiveness of this methodology through case study of producing reservoirs in Dabka field within sub layers of Hazad sands, which are thin and discrete in nature, by using 3-D Seismic data for micro-analysis of geological complexities, including generation of various fault pattern, understanding the trap mechanism, hydrocarbon migration and distribution.

To enrich these factors, mosaic of time and horizon slices are generated and studied critically in an interval of very small time. Paleo- structural analysis method is also applied on seismic sections. The method reveals that the area has been subjected to polyphase deformation. A major fault (Gajera fault) to the west of this field plays a key role in hydrocarbon migration towards the Dabka field as its throw varies along its length from negligible to as much as 30 to 40 meters or even more, forming various fault closures in hanging wall side, where hydrocarbons trapped. Dabka field is situated on the positive inversions created by other N-S bounding younger faults, existing in the foot -wall side of this fault, and hydrocarbon are trapped on structure or fault closures, on the way where Gajera fault shows negligible amount of throw, while the Wells falling on the way where Gajera fault has sufficient amount of throw, are devoid of hydrocarbons.

Sedimentary architecture, and lithology prediction which were subsequently used to predict new prospective areas, refine the drilling plan of various locations. Based on this study, recently drilled development wells have enhanced the production from this old field.