"Although the Eagle Ford shale is early in its history, the study provides a comprehensive examination of per well recovery and decline data in the South Texas trend using the latest production information up to early 2012. Individual forecasts of the estimated ultimate recovery (EUR) were made for more than 1,000 horizontal wells in the South Texas Eagle Ford shale trend and statistics were developed for EUR in the 10 primary counties where development is occurring. The study used rate vs. time plots and included all the producing wells in the trend which have decline data believed to be sufficient to project EUR. Normalized decline curves were developed for each county and distributions of EUR were produced. In addition, for a portion of the wells, correlations were made between EUR, frac size, horizontal length and the date of first production.
The results show that for the 10 county trend, the average and median EUR per well were 206,779 barrels of oil equivalent (BOE) and 160,519 BOE, respectively. Of the counties with more than 50 wells, the best are DeWitt (403,715 BOE) and Karnes (210,801 BOE). Live Oak, with only 28 wells averages 248,818 BOE. The normalized rate vs. time plots show minor hyperbolic behavior. In fact, for all the wells in the study, the normalized oil decline was 76% and the gas 60%, with hyperbolic exponents of .25 and .40, respectively. The wells have clearly become better since the start of horizontal drilling, but the average performance has not shown much improvement since mid-2010 even as the frac sizes became larger. The best well performance has generally come from wells with horizontal legs in the 4,000 to 5,500 ft. range.
The South Texas Eagle Ford shale trend is one of the most active in the US, adding approximately 100 new producing leases each month. Although a great deal is being written about the trend, there is a lack of independent, hard data on per well reserves. This study provides an early look at individual well ultimate recovery."
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