This paper presents the results of a fracture feasibility and design study, treatment execution and post treatment evaluation for a hydraulic fracture campaign in the Sawan and Miano Gas fields, located in the Sindh Province, Pakistan. This first successful fracture campaign (in four wells) was conducted from December 2005 to July 2006. One well is located in the Miano and three wells in the Sawan gas field targeting the Lower Goru B and Lower Goru C sands at depths of about 3,300 m. Several injection tests and minifracs prior to the main treatment were performed to quantify closure stress, fluid leakoff, perforation friction, near-wellbore tortuosity, and fracture complexity. Issues such as formation water sensitivity and fines migration are discussed. High reservoir temperature, proppant flowback issues and risk of fracing into a water transition zone are some of the challenges faced during the fracture campaign. A variety of fracture design sensitivities were performed to evaluate the effects of pad size, treatment size, fluid and proppant types on fracture geometry, conductivity and gas production.
In the Sawan, fracturing was found to be simple as opposed to more complex fracturing in the Miano area. Permeability ranges from low 0.06 mD to moderate 8 mD in the four fractured wells. Treatment designs were adjusted accordingly to minimize screen-out risk and maximize fracture stimulation efficiency. To help reduce proppant flowback into the wellbore, partially cured, resin-coated proppant was pumped at the end of the treatments. A low-polymer loading, high-temperature, CMHPG fracturing fluid was used due to a high-temperature reservoir. This type of fluid provided high fluid viscosity for proppant transport while also minimizing polymer damage to the proppant pack. The fracture campaign has successfully increased the gas production by two to four folds.
Author(s): E.P. Lolon and D.J. Quirk, Pinnacle Technologies; C.K. Enzendorfer, OMV UK; U.B. Bregar and S.Q. Shah, OMV Pakistan; and M.J. Mayerhofer and C.L. Cipolla, Pinnacle Technologies
Paper Number: SPE 113932