Abstract

Most gas wells which are completed in low permeability (tight) formations of the Appalachian permeability (tight) formations of the Appalachian Basin, such as Big Injun, require stimulation to achieve (commercial production. The general responsiveness of these formations to a certain set of the stimulation treatments design parameters remains uncertain. Although the stimulation treatments have enhanced the production, the question that needs to be answered is whether the treatment designs are, simply standard approaches based on past practices or they represent the optimum designs.

The stimulation and production data from a number of Big Injun wells in West Virginia have been collected and analyzed in order to develop the optimum design guidelines for successful applications. The production data were analyzed with the aid of production decline type curve to establish basic production decline type curve to establish basic reservoir parameters. A commercial simulator and stimulation data were then utilized to much the production history in order to evaluate the formation production history in order to evaluate the formation characteristics. The results of history matching were then utilized to optimize the treatments on each well. Cost analysis were subsequently performed to select the most economic treatment. The results of this preliminary study indicated that the optimum preliminary study indicated that the optimum treatment designs based on the reservoir parameters can further improve the economic production. The general guidelines have been established for more effective and economical fracturing treatment for the Big Injun Formation.

Introduction

Hydraulic fracturing has become the most widely used well stimulation method. Hydraulic fracturing has evolved into a highly technical procedure with an array of different methods and approaches available. Hydraulic fracturing is especially helpful in improving production front low permeability sandstone formations production front low permeability sandstone formations that are otherwise difficult to produce economically. The Big Injun is a typical low permeability sandstone formation which has produced gas in West Virginia since 1886. Today, it accounts for a large percentage of the gas recovered in the state. Hydraulic fracturing has been the major factor in the continuing economic gas production from Big Injun over the past 20 years.

The development and application of various stimulation treatments has improved the outlook for the Big Injun to continue as an integral source of gas production in West Virginia. However, the responsiveness of the formation to different sets of the treatments design parameters remains uncertain. Consequently, the treatment designs which are commonly employed in West Virginia are simply standard approaches based on past practices and may not represent the optimum designs. It is, therefore, necessary to study the results of the stimulation treatments in order to evaluate the effectiveness of the treatments designs and the degree of improvement that can be achieved through optimization. More specifically, the objective of this study is to establish general guidelines for more effective and economical fracturing treatment relative to Big Injun Formation.

Background

Stratigraphically, Big Injun sandstone is the top member of the traditionally named Pocono Group and represents the Upper Meramecian Series of the Mississippian System. In the past, it has been often confused with the middle Mississippian lower Greenbrier limestones which overlaps the Pocono Big Injun in the northern part of the state. The Greenbrier extends into central West Virginia while the Pocono Big Injun reaches into the northwestern region of the state. In addition, the Big Lime is also responsible for much of the production attributed to the Big Injun in southern West Virginia.

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