C. Rena Rasor and Doug Walser, BJ Services Company, USA
For a number of years, controversy has arisen as to the most efficient way(s) to accelerate the rate of reserve recovery from ultra-low permeability carbonate reservoirs. Efforts were undertaken to locate and study a sufficient number of wells that would be representative of this issue, and that would clearly distinguish naturally occurring reservoir parameters from man-induced processes. The production from a localized group of Strawn wells in Crockett County, Texas was examined and normalized by permeability, porosity, initial static reservoir pressure, and productive height to establish the impact of various completion methodologies. Flowing pressure transient analysis was performed on each well to determine permeability, effective fracture half-length, drainage area, and aid in the normalization process. Stimulation of the Strawn was divided into three categories: propped fracture stimulation, crosslinked acid treatments, and all other acid treatments. For each of these categories, average fracture half-lengths and normalized production are compared and contrasted.