Abstract

Unconventional shale plays have been rapidly developed over the past six years with over 13,000 wells completed in the Eagle Ford alone (Wood Mackenzie 2015). This pace has been characterized by constant changes in development and operations, complicating industry's ability to analyze and compare well and reservoir performance. The resulting challenge faced by the petroleum industry is to identify metrics that relate to long-term well and reservoir performance.

The petroleum industry uses various metrics to analyze and report unconventional well performance. Most of the traditional single well performance metrics (i.e. Initial Production (IP), 30 day cumulative Barrels of Oil Equivalent (BOE), etc.) do not explicitly account for geology, fluid behavior, well operations, or drainage volume. As a result they often do not correlate to long-term well performance and should not be used for development decisions (i.e. best practices on completions, well spacing, production operations, etc.). This paper will discuss strengths and weaknesses of various performance metrics and describe the modification and application of a well-established metric to address some of the limitations described above. The modified metric has been validated using long-term production data from hundreds of Eagle Ford wells. The paper will also show how the metric was applied to support development decisions in BHP Billiton's Black Hawk acreage.

Introduction

The horizontal shale revolution in the Eagle Ford reservoir began with Petrohawk's first well in Hawkville, STS 1H, in 2008. BHP Billiton's acquisition of Petrohawk's Eagle Ford acreage in 2011 has since resulted in over 900 wells being drilled in its flagship Black Hawk acreage and over 530 wells in Hawkville (Fig. 1). Current producing well count from the two fields is over 1,400 wells. Black Hawk development is mainly focused in De Witt County in partnership with Devon Energy. Fig. 2 shows a typical well from the Black Hawk field and its heterogeneous petrophysical properties. A unique combination of several factors—structural setting, high total organic content, low clay content, and an overpressured reservoir in most of the acreage—make Black Hawk a world-class unconventional field. However, development is complicated by several factors such as depth ranging from 11,000 feet to 13,500 feet, variable thickness (Fig. 3) and fluid properties (Fig. 4), and extensive lateral (Fig. 5) and vertical heterogeneity.

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