Porticus

ABSTRACT Hydraulic Fracturing of the Rewan and Showgrounds formations in the Namarah-Parknook fields of the Red Cap Block was performed in an attempt to establish commercial rates of gas production from a large volume of potential gas reserves in the Surat Basin. These formations had not been previously-fractured in Australia. A geological and engineering study was made of the subject area before proceeding with the fracture treatments. This quantified the available gas-in-place and allowed selection of the best candidate wells for stimulation. Several cores were available from wells in the area and selected lengths were sent to the service company stimulation laboratory in the U.S.A. for detailed analysis to determine the best parametric values to employ in the computer-assisted design of the proposed fracturing treatments. Four stimulation treatments were carried out on three wells in the area, with varying results. Similar sized fracture treatments were performed, but many changes were made to the pre-frac completions as well as the treatments themselves as they progressed. The changes were made to optimize designs, based on experience gained, and reduce costs while still achieving well-contained deep fractures in the pay zones. The first treated well, Namarah No. 2 was extensively production tested before stimulation, to allow an accurate comparison with post-frac production rates. Selection of the proppant was based on the crushing forces on the proppant as well as on the ultimate reservoir pressure at depletion of the formations proposed for fracturing. Pumping rates were determined by the thickness of the pay zone to be fractured and the estimated degree of containment which could be expected from the natural barriers to fracture propagation contained in surrounding formations. Size of the treatment was based on the natural permeability-thickness of the reservoir rock and drainage area, as well as the need to achieve commercial gas flow rates from successful wells. Extensive use of computerized on-site monitoring technology and equipment was employed.