--> Understanding Complex Fluid Contacts Through Integration of Seismic and Pressure Data With Well Information: A Case Study of Deep Carbonate Reservoirs of Kuwait

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Understanding Complex Fluid Contacts Through Integration of Seismic and Pressure Data With Well Information: A Case Study of Deep Carbonate Reservoirs of Kuwait

Abstract

Kuwait Oil Company is currently delineating and developing a deep naturally fractured carbonate reservoir Complex of Toarcian age in the northern part of Kuwait, encompassing a large area of over 1700 square km, to meet the accelerated Oil & Gas production targets. These reservoirs occur in the depth range of 14500’ to 15500’ with HP/HT and sour operational envelope. Over 120 deep well penetrations, spread over the entire field complex, have facilitated a continuously evolving understanding of reservoir and fluid contacts. A systematic campaign of extensive data acquisition, including conventional coring (approximately 16000’ cumulative) and detailed core description in a consistent manner, enabled a thorough understanding of the depositional setting and building of a robust sequence stratigraphic model. A viable structural evolution model for these fields has been built, based on detailed studies carried out over the past few years, taking into account key kinematic observations from well and seismic data as well as analogue information and linked to the known regional phases of deformation. Since the early delineation wells, a phenomenon of hydrocarbon down to (HDT) beyond the structural spill point has been observed. This phenomenon could partly be explained with the help of fault blocks derived based on seismic attributes. With the increased maturity of the well data and reservoir pressure data, originally envisaged block boundaries could not explain the observed phenomenon. A careful revisit of the seismic data, including integration of new generation seismic data, further supported the need to revise the block boundaries to explain the fluid contact variations across the field. In one of the fields of this large complex with excellent reservoir properties, a consistent northward deepening of contact is observed. The fluid contact is mostly conformable to structure and with a relief of about 600’ (ranging from 15150’ to 15750’ TVDSS from south to north). This necessitated invoking non-horizontal contact, linked to structural kinematic changes over the period of charging history. This new understanding has offered significant upside potential by way of additional appraisal areas in this hitherto undrilled parts of this Complex. Through this paper we are presenting the evolution of the understanding of the fluid contacts with additional information through time leading to identification of additional opportunities for further delineation and development.