Hydraulic Fracturing Of Tight Gas Reservoir Of Pab Sandstone At POGC Rehman-1

Abstract

POGC Rehman-1 discovered gas from the Pab sandstone in mid-2009. The well had low productivity primarily due to low reservoir permeability. In December 2009, the well’s Upper and Lower Pab zones were fractured, resulting in a four-fold increase in production. Post-frac testing of the zones discovered very little proppant flowback. This paper outlines the history of this successful hydraulic fracturing treatment in the Kirthar region. The document also discusses the detailed job design, fracture modeling, pre-frac production model calibration, and sensitivities to treatment size. A series of fracture designs was developed to evaluate the uncertainty in fracture geometry predictions. The successful stimulation of a low-permeability gas reservoir dictated placing a long conductive fracture. An important aspect of fracture design is fluid selection. The fluid must maintain excellent proppant transport characteristics throughout the pumping sequence, yet break rapidly and cleanly once the treatment is completed. Another important aspect of fracture design: proppant selection. The proppant is basically the life of the fracture and should maintain adequate conductivity throughout the designed exploitation life of the fracture and completion. The fracturing program and the main treatment’s actual execution are presented in the paper. Operational issues are also discussed. One-hundred mesh sand was used to minimize the risks associated with pressure dependent leakoff (PDL) into natural hairline fractures seen on the FMI log. Post-fracture well-testing data was recorded and analyzed. The results were used to quantify the fracture effectiveness.