Exploring for Fractures in Tight Gas Reservoirs, North Oman

This reference is for an abstract only. A full paper was not submitted for this conference. As gas operator on behalf of the Oman Government PDO has been active in a mature basin for ca 18 years. The traditional focus for gas exploration in the north has been on deep Haima reservoirs. These have been successfully targeted in a proven Haima silicilastic "play fairway" where all the classic play elements have been are recognised and areally defined in a target window of ca 4 - 5km. The approach has led to the discovery and development of a number of significant deep gas/condensate fields including: Barik, Saih Rawl, Saih Nihayda and Kauther. Periodic attempts (ca 5 year cycle) to move out of the fairway area based on a challenge of prior geological models, developed with new insights, have often led to disappointing results. Outside the mature fairway all the play elements (reservoir, charge, structure, seal) are still present but an additional overriding "reservoir recovery" play risk becomes significant. Reservoir recovery captures (at a play level) subtleties in reservoir composition/facies, burial history and charge timing that have a significant overprint on the overall play risk. To manage the "operational" factors impacting reservoir recovery in the exploration arena ongoing work pursues optimising drilling, completion and testing procedures. The presence of an open fracture network in a recent discovery has triggered a possible geological "game changer" with the potential to significantly reduce recovery effectiveness risk and unlock significant additional gas volumes across a large area. With the aid of a number of key indicators (rock mechanical properties, recent flexure, fault orientation and late charge) a working model for the deliberate pursuit of fracture systems in an exploration setting (a "fracture play") is being developed. This workflow in conjunction with optimised operations may allow a redefinition of recovery effectiveness risk.