In 2009 Petroleum Development Oman LLC (PDO) started an ambitious tight and deep gas exploration programme, exploring for previously untapped reservoirs, both conventional tight gas plays as well as deep unconventional gas resources. These resources are typically in previously undrilled formations at great depths, highly overpressurized with high temperatures, and uncertain fluid fill and composition. The unique geological properties of this type of reservoir require different strategies and technology deployment in order to make them viable and sustainable (Briner et al., 2012).
With unique geomechanical, reservoir, and geological properties, some of the large gas-bearing prospects within the Fahud Basin such as the Khulud exploration area require innovative and complex drilling, completion and fracturing practices. A revised hydraulic fracturing execution workflow, with specific technology application, has been developed in order to account for such geological and reservoir complexity. Because of the uniqueness of the structure in terms of depth, temperature, reservoir pressure and stresses, different strategies should be used for successful hydraulic fracturing.
This paper demonstrates the changes to the original understanding of fracturing processes and execution in order to achieve successful fracturing implementation, production testing and reservoir evaluation. Six main aspects are covered, these are as follows: abrasive jetting perforations as a standard application, fracturing fluid optimization in HPHT environment, modified fluid design, stair-step ramping of the pumping schedule, engineered fracture design to achieve sufficient fracture length and conductivity and post-frac flow-back monitoring and assessment.