Production Acceleration or Additional Recovery?-A Look Back at Three Published Field Trials To Determine the Long Term Benefits of Improved Fracture Treatments
- Kelly Wayne Blackwood (HighMount E&P LLC) | Patrick Joseph Handren (Denbury Resources Inc) | Mark Aaron Chapman (CARBO Ceramics Inc.) | Terry T. Palisch (CARBO Ceramics Inc.) | Jonathan W. Godwin (CARBO)
- Document ID
- Society of Petroleum Engineers
- North American Unconventional Gas Conference and Exhibition, 14-16 June, The Woodlands, Texas, USA
- Publication Date
- Document Type
- Conference Paper
- 2011. Society of Petroleum Engineers
- 5.8.1 Tight Gas, 2.5.2 Fracturing Materials (Fluids, Proppant), 4.1.2 Separation and Treating, 3.2.3 Hydraulic Fracturing Design, Implementation and Optimisation, 5.2.1 Phase Behavior and PVT Measurements, 2.4.3 Sand/Solids Control, 2.5.1 Fracture design and containment
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There is no doubt that improved frac designs can increase production rates from many reservoirs. However, do these changes merely accelerate recovery, or is incremental production gained by changing the fracture design?
Results from field trials are often published within a year (or even less!) of the initial design changes, and EUR projections are required to forecast the long-term economic impact. This paper will document a re-examination of three tight gas case studies published in the past ten years to determine whether recovery projections were accurate. Included are a review of field studies performed in the East Texas Haynesville Lime, the West Texas Canyon Sand, and the East Texas Cotton Valley-Taylor Sand. The original studies in these tight gas formations were specifically performed to assess the impact of increased fracture conductivity on production. In all cases, the initial analyses documented that increasing conductivity appeared to increase production and recovery.
By revisiting these case studies using extended production data, a more rigorous determination of recovery and associated economics will illustrate whether recoverable reserves are increased from tight gas reservoirs with careful modification of fracture designs. This paper will speculate on the mechanisms that may allow incremental reserves to be captured from some reservoirs, and will evaluate the uncertainty of reserve forecasts constructed from less than one year of production data. This summary should be of interest to any engineer who must estimate the recovery impact of completion changes when only limited production data is available.
Engineers have been making changes to their wells for years to improve performance in an attempt to increase the reservoir's ability to flow to the well. Since the first commercial hydraulic fracture treatments in 1949, treatment designs have evolved - from experimentation with massive hydraulic fractures to proppant-less water frac's, from 50 and 60 pptg cross-linked gels to slickwater frac's - all are designed to maximize the economics of the well. Engineers also continue to improve fracture conductivity through the use of cleaner fluids, better breakers, premium proppants, increased proppant concentrations, surfactants, gelled foams, slick-water and hybrid fracture treatments tailored to the formation. These improvements are all done in an effort to improve the production and ultimately the economics of the wells. SPE 119143 [Vincent 2009] summarized over 200 published studies that show the benefit of increased conductivity in oil, gas and condensate wells; documented by hundreds of authors representing over 150 companies around the globe. These studies range in depths from shallow to deep, oil rates from 2 barrels of oil per day (bopd) to over 25,000 bopd, gas rates of less than 1 million standard cubic feet per day (MMSCFD) to over 100 MMSCFD, and permeabilities from Darcy to nano-Darcy. In each case, increasing conductivity increased production.
|File Size||534 KB||Number of Pages||10|