Abstract

The Marcellus Shale is one of the main U.S. shale plays with more than 140 trillion cubic feet (Tcf) of recoverable gas/condensate (E.I.A) in Pennsylvania and West Virginia. Using the appropriate completion and stimulation designs for reservoirs in a given location is crucial to increase the productivity of the play. Understanding rock properties and reservoir characteristics in gas condensate area and their behaviors during the well stimulation is necessary in order to optimize treatment design. This case study aims at optimizing well and completion design parameters such as well spacing, lateral length, azimuth or hydraulic fracturing properties and improving well productivity. An integrated reservoir study involving geomechanics, fracture design and production analysis was carried out, coupled to a multivariable statistical analysis. The purpose of this paper is to apply multivariable statistical analysis in conjunction with production analysis to understand the relationships between rock properties and hydraulic fracturing efficiency within the reservoir. Fifty percent of the Marcellus Shale is composed of clay in the area of interest and typically, clay shales are anisotropic in strength and deformability. The brittle failure characteristics vary from east to west of the play which can affect the proppant transport and ultimately the well productivity. The investigation is based on both proprietary and public information data for the Marcellus formation (around the area of interest in Marshal County, West Virginia). Production proxies, such as maximum gas and condensate rate in the first 12 producing months were selected and merged with well completion and stimulation data. Final data sets were then subjected to a multivariable statistical analysis and a commercial Geographic Information Systems (GIS) application was used to understand geographical performance variation within the play. Fracture modeling and Rate Transient Analysis (RTA) were applied to this study to identify flow regimes and obtain determine some hydraulic fracture and reservoir properties. At last, the relationships between well performances, completion design and reservoir behavior were better understood.

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