The Effects of Proppant Selection Upon Well Productivity—A Review of Over 650 Treatments in the Cardium Formation

摘要

Effects of proppant selection on well productivity are demonstrated in a large case study covering 2,300 square miles [6,000 square kilometers] in Alberta, Canada. In 80% of cases studied, wells fractured with ceramic proppant provided significantly higher gas production rates compared to wells propped with sand or other materials. The most frequently stimulated formation in the Western Canadian Sedimentary Basin (WCSB) is the Cardium formation of the Late Cretaceous period. Records indicate that across the basin the Cardium formation has received over 12,500 fracture stimulations during the last 50 years. This study includes a review of 1,600 wells operated by 96 companies. On average, 156 new wells have been drilled annually since 2000. Record numbers of new wells were completed in 2004, and the number of Cardium wells completed in the last four years exceeds the total from the preceding two decades. A detailed database containing available fracture treatment and production data was compiled from government records and service industry sources. This paper summarizes a study of over 750 well stimulations. Various stimulation strategies have been employed in the Cardium development. This paper examines productivity of hydraulic fractures propped with various materials and placed with a variety of fluid systems. Wells in this study were stimulated with as low as 2,200 lbm [1 tonne] to nearly 407,000 lbm [185 tonne] of proppant per well in one to five stages. Analyses suggest that significantly greater economic return has been achieved when fracture designs are optimized. In this study, the most common design was 132,000 lbm [60 tonne] of proppant placed with a hydrocarbon-based fluid. For this treatment design, the average first year production for wells receiving 132,000 lbm [60 tonne] of sand was 302 MMscf [8.5 × 10~6 m~3] of gas. Wells stimulated with 132,000 lbm [60 tonne] of ceramic proppant averaged 420 MMscf [11.9 × 10~6 m~3] production during the first year. Benefits vary with job size, fluid type, and other factors. The incremental cost of ceramic proppant is usually recovered within 30 days, generating a significant increase in profitability. At current gas prices, average return on investment achieved by optimizing proppant selection greatly exceeds 100%. Production from Cardium oil wells was also found to increase with proppant concentration and with proppant size. A preliminary review suggests that oil production has been significantly improved with higher conductivity fractures. While a full statistical review remains underway, the initial comparisons suggest that further increases in proppant conductivity should be considered. Additional information is provided to assist fracture optimization strategy for both oil and gas wells in the Cardium formation.