It is common industry knowledge that horizontal shale gas development is enhanced by drilling in the orientation parallel to the local minimum principal horizontal stress such that the induced hydraulic fractures grow parallel to the maximum horizontal stress during completion. Given the incongruous nature of mineral leases in the Marcellus Shale play, operators often drill in orientations that are sub parallel to this preferred azimuth in the interest of saturating acreage positions. What remains unknown is the degree to which this deviation from the preferred azimuth affects treatment pressures and/or more importantly well productivity. This case study will incorporate proprietary and public data in order to relate Marcellus well productivity to deviation from preferred horizontal well azimuth.

In the effort to assess the impact horizontal wellbore azimuth bears on completions and well productivity, the productivity of wells in EQT’s core development areas has been correlated with the well’s deviation from minimum horizontal principal stress as determined from the analysis of over 25 image logs and cores across Pennsylvania and West Virginia. Furthermore, over 500 public domain wells released from the PA DEP and WV Geological Survey have been parsed and normalized to determine whether or not similar correlations can be made. The conclusions drawn from this study will determine if productivity is related to preferred wellbore azimuth and the regional variability of the relationship. Technical, logistical, and economic analysis will be applied to conclusions.

This study has drawn some value from initial Marcellus public datasets that, while statistically significant in size, often lack in detail. The shortcomings of this large dataset will be normalized by the detailed datasets acquired from EQT’s core development areas. The ability to relate deviation from preferred wellbore azimuth to productivity will allow EQT and other operators to develop acreage more efficiently and optimize capital allocation.

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