Assessment of probabilistic parameters for Barnett shale recoverable volumes

The Barnett shale is a renowned Resource play and one of the most developed in North America with enormous hydrocarbon potential located in the Fort Worth basin of North Central Texas. It is currently the largest producing natural gas field in the United States, averaging 5.5 Bcf/d and cumulative production of 9 Tcf as at the end of 2010. However, in spite of its success, it is difficult to predict well performance and reserves with certainty largely due to geological complexity and completion type. Thus, it is common to see wells in the same producing interval exhibiting large differences in producing rates and estimated ultimate recoveries (EUR). Peak monthly rate (PMR) has been found to be quite useful by some operators in predicting gas reserves because of its favorable correlation with EUR. In this paper, 2,932 Horizontal gas wells were sampled from the top six producing counties in the area and analyzed to confirm if peak month rate can be a good predictor of gas reserves by determining its correlation with EUR. Also, the P10/P90 ratios were assessed for both EUR and PMR. P10/P90 ratios have been found useful in measuring uncertainty in performance and were used extensively in this work to analyze and compare performance of wells across the six counties studied. In addition, P10/P90 ratios can be an indicator of proper population size for use in probabilistic analysis with the given data set. Most of the counties proved to have an ample data set for probabilistic use. Since geological complexity and completion efficiency are common features affecting performance in resource play reservoirs, several parameters such as: Reservoir depth, Gross thickness, BTU content and Lateral length were reviewed and analyzed with respect to its effect on performance in the Barnett shale.