When oil prices are low, the oil industry tends to reduce its capital expenditure to fund new projects, such as exploration and development projects. The reduction in exploration activity ultimately affects the operators’ reserve balance. These conditions push each operator to use innovative solutions to increase reserves. Hydraulic fracturing is considered one of these solutions because it enables revisiting the possibility of producing an uneconomic reservoir with the existing wells. One reservoir that is being reevaluated is the Karim formation located in the Karim Small Fields (KSF), the Sultanate of Oman.
The Karim formation is divided into three segments, with the most promising being the Lower Khaleel, which was initially considered uneconomic to develop. The Khaleel is a sandstone formation at approximately 2000 m depth, with fair porosity and permeability and containing moderate-viscosity oil. The current recovery factor in the Khaleel is still less than 5%, and it is not considered for a full-field development plan due to low production results.
Because the wells drilled in the Khaleel formation were not prepared for a fracturing operation, several challenges appeared during early review, including the well trajectory and azimuth, completion condition, intervention strategy, data availability, and reservoir understanding on the formation water source and its connection to the Khaleel. The project was separated into three phases: feasibility and technical study phase, fracturing trials and evaluation phase, and fracturing understanding and optimization phase. Results are available for the first two phases, and a plan has been formulated for the third phase.
The feasibility and technical study involves understanding the geology, geomechanics, and petrophysics of the wells in which a fracturing operation was performed previously in a different formation. This study was followed by a candidate selection step involving more than 10 existing wells. The candidate selection process used a novel workflow to incorporate all the challenges into the selection criteria. Results of the candidate selection phase led to selection of the top three wells for fracturing operations in the Khaleel formation. Two out of three wells were selected for hydraulic fracturing treatment in the initial trial phase. Observations and results have been obtained from the execution of the trial hydraulic fracture jobs in these wells.