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

Abstract

Effects of proppant selection on well productivity are demonstrated in a large sample case study covering 2,300 square miles [6,000 square kilometerskm2] 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.This formation is also known to contain natural fractures resulting from location-dependent tectonic strain.Records indicate that across the basin the Cardium formation has received over 12,500 fracture stimulations during the last 50 years.About 4,000 detailed fracturing treatments were reviewed to define the smaller focus area. This This study includes a review of 1,600 well boress in an area 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. Drilling activity peeked at 163 wells in 2003 and has averaged 140 wells per year since 2000.Drilling in the previous decade averaged 28 wells per year.This paper reports on analyses derived from a database containing 680 records representing all available fracturing data.These records were compiled from governmental, service industry, and operating company sources. Various stimulation strategies have been employed in the Cardium development.This paper will 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 200 tonnes [185 tonne440,000 lbm] 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 x 10[6] m[3]] of gas.Wells stimulated with 132,000 lbm [60 tonne] of ceramic proppant averaged 420 MMscf [11.9 x 10[6] m[3]] production during the first year.30Benefits vary with job size, fluid type, and other factors.TThe incremental cost of manufactured ceramic proppants 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. Introduction Hydraulic fracturing is required to achieve economic production rates from most Cardium gas wells.In fact, records indicate over 12,500 stimulation treatments have been performed within this formation throughout the WCSB.Despite this extensive experience, no clear consensus has emerged from the various operators on fracture design optimization.The purpose of this paper is to survey and evaluate the productivity achieved with various treatments.A detailed database was compiled from government and service industry records. Stimulation treatments are classified by fracturing fluid type, proppant type, and proppant quantity placed in each well.

Tight Cardium Multistage-Fractured Horizontal-Oil-Well-Performance Study Focusing on the Effectiveness of Various Fracture-Fluid Systems

“…In south and central Alberta, the Cardium contains generally light sweet crude oil. In the foothills to the northwest, the Cardium may contain rich gas (Rightmire et al 2005).…”

Enzymatic degradation of polyacrylamide in aqueous solution with peroxidase and H2O2

“…The high viscosity of the fracturing fluid suspends the proppant for transport into the induced fractures and reduces the effect of gravitational settling that would otherwise result in poor distribution of the proppant. The proppant used in fracturing varies from well to well but generally there are three main types: sand, resin‐coated sand, and ceramic . In general, the fracture conductivity (and so the rate of flow of oil or gas) is determined by the proppant strength and uniformity with the strongest, most uniform proppant resulting in the highest fracture conductivity and production yields …”