Massive Hydraulic Fracturing In The Eastern United States
Authors: Jennings Alfred , Darden Wallace , Wenzel Ray , Shrut Robert , Foster John 
Published: December 2007

Large volume fracturing treatments consisting of several hundred thousand gallons and very large quantities of sand are being conducted throughout the United States. These treatments are conducted in an effort to provide sustained production increase from provide sustained production increase from extensive, low permeability reservoirs. Several such treatments have been conducted in the Northeastern United States. Application of the massive fracturing approach in this area is unique since the low reservoir temperatures relatively low reservoir pressures, and formation types make fracturing fluid selection and treatment method primary considerations. This paper describes from geology and laboratory paper describes from geology and laboratory tests the formations involved, types of treatments that have been conducted, and indicates preliminary results based on case histories. preliminary results based on case histories

Introduction

In the present search for oil and gas, many geological reserves are being tapped that were considered uneconomical in the past. There are currently several vast low permeability formations that are being developed in the United States. Due to the nature of these formations, they must be stimulated, usually by hydraulic fracturing, to produce economically. A considerable amount of information concerning large volume stimulation treatments is available to the industry.

The eastern part of the United States is somewhat unique in that large volume massive fracturing treatments were not conducted in this area until recently. This paper will deal with six large volume treatments that have been conducted in the Devonian Shale and the Clinton formations in this area.

The Devonian Shale is a massive siltstone deposition spread throughout West Virginia, Kentucky, Pennsylvania, New York, and Ohio. Primary characteristics which indicate it Primary characteristics which indicate it could be stimulated effectively by large volume fracturing are its widespread deposition and its low permeability. Generally, it is considered to be naturally fractured and will be further described in the Geology Section.

The Clinton has a similarity to the Devonian Shale in that this geological formation also covers a massive area. Various stimulation approaches have been tried in the Clinton with some degree of success in many areas.

The scope of this paper is to briefly describe the Devonian Shale and Clinton Sandstone geology and to describe the large volume treatments that have been conducted to date in these formations.

GEOLOGY OF THE DEVONIAN SHALES

The Upper and Middle Devonian Shales are extensive formations of considerable thickness The Devonian Shales underlie approximately 100,000 square miles in Kentucky, Ohio, West Virginia, Pennsylvania, and New York. As shown in Figure 1, the Devonian Shales are also present in Michigan, Indiana, Illinois, Tennessee, Mississippi, and Arkansas, but the significance of the Shales in these areas to the petroleum industry has not been ascertained to date.

The Upper and Middle Devonian Shale is a complex mixture of brown, brownish-black and gray shales on the eastern side of the Appalachian Basin. The character of the shales grade into a sandier facies with more silt-sized quartz grains as one traverses the Shale from southwest to northeast.