Paving the Road for the First Hydraulic Fracturing in Tight Gas Reservoirs in Offshore Abu Dhabi

Abstract

Abstract The paper contributes to the ongoing efforts of Abu Dhabi National Oil Company (ADNOC) to improve gas production and supply in view of increasing demand and diminishing conventional gas reservoirs in the region. The conditions of unconventional gas reservoirs with potentially economical volumes of gas in Abu Dhabi are tight abrasive deep sand reservoirs at high temperature. Thus it inevitably tests the limit of both conventional thinking and technology. Accurate prediction of well performance is a major challenge that arises during planning phase. The paper aims to simulate first hydraulic fracture in tight reservoirs of Abu Dhabi. The formation studied in this paper is characterized by quartizitic sandstone layers and variably colored shale and siltstones with thin layers of anhydrites from late Permian to carboniferous age and constitutes a reservoir rock at the lower permeability range less than 1 milli Darci. When fractured, the expected well flow rates of the offshore deep gas wells could reach levels similar to production flow rates in tight gas reservoirs encountered elsewhere in the region. Flow is described as transient initially with high production rates and rapidly declining towards pseudo-steady production at lower but economical rates. The unknown tectonics in a new area represents the higheset uncertainty. In fact hydraulic fracture is a test of the tectonics if all others factors are known. An earth model was built and tested based on data and core plug samples from two offset wells. The reservoir and core analysis indicated some contrast over the structure which may add complexity in different locations of same field but nevertheless it is possible to design selective treatment with good fracture containment and therefore acceptable simulation results. A strategy that is flexible at this stage is of highest value whereby concrete measurable steps are taken to confirm technology is implemented safely and efficiently in order to pave the road towards a clean energy resource in the future.