Evaluating Gas Production Performances in Marcellus Using Data Mining Technologies

Abstract Shale gas development – enabled by the advent of advanced horizontal drilling and hydraulic fracturing technology - has become, over the past several years, a very important energy resource. The estimated ultimate recovery of natural gas from the Marcellus Shale in West Virginia alone has been estimated to be between 98 and 150 trillion cubic feet (Tcf). In 2008, 25 billion cubic feet (Bcf) of natural gas was produced from 41 horizontal wells in West Virginia. By 2012, that gas production reached 301.7 Bcf from 631 horizontal wells. However, the hydraulic fracture stimulation of horizontal wells with multiple stages mechanism, by which that natural gas is produced from shale, is complex. Significant uncertainty about production performance in these unconventional reservoirs represents significant risk for whether resource development will lead to favorable technical and economic performance. The objective of this paper is to use post-hoc analysis techniques to identify correlations between gas production performance of a well and attributes of its completion and geological setting, and to identify those factors most important to predicting gas recovery performance. To accomplish this, the geological attributes of Marcellus Shale in West Virginia were characterized through literature review. Then, the set of 631 wells was down selected to a representative subset of 187 wells for which complete data are available, including well location, completion data, hydraulic fracture treatment data and production data. The wells were classified into four groups based on geological setting. For each geological group, engineering and statistical analyses were applied to study the correlation between well performance and well completion attributes through traditional regression methods. Important factors considered to affect gas production include number of hydraulic fracture stages, lateral length, vertical depth, proppant volume, and fracture fluid volume and treatment rate. The numbers of hydraulic fracture stages and lateral length have relative large influence on well performance. With these analysis results, it was possible to estimate well-scale ultimate natural gas production performance as a function of known geological conditions and completion parameters. The results lead to a better understanding of the trends in Marcellus Formation well performance. These approaches could, in the future, help to optimize stimulation treatments and well completions and improve resource recovery in the Marcellus, and other unconventional hydrocarbon formations.