A Case Study for Drilling and Completing a Horizontal Well in the Clinton Sandstone
Authors: Murray William F. , Schrider Leo A. , Mazza Raymond L. , Yost Albert B. 
Published: December 2007

Horizontal well drilling for the recovery of natural gas and oil has been touted as the panacea for optimum recovery from hydrocarbon reservoirs. This technology has been applied to reservoirs throughout the world, primarily in environments such as the North Sea off the coast of Great Britain and the Austinchalk in Southeastern Texas. To date, very few wells have been attempted in the Appalachian Basin. To test this technology in the Appalachian Basin, a joint effort between Belden & Blake Corporation and the U.S. DOE resulted in the first horizontal well successfully drilled and stimulated in the Silurian Clinton Sand formation. The Central Waste #14 well (CW #14), is located in Smith Township, Mahoning County, Ohio, which is one of the better remaining areas for Clinton Sand developmental drilling. The CW #14 was spudded in October 1993 and drilled to a total measured depth of 6,505 feet at a maximum inclination of nearly 92 degrees from vertical with approximately 1,320 feet of Clinton interval exposed. Total Clinton interval footage greater than 85 degrees was about 1,142 feet. Three hydraulic fracturing stages were successfully completed within the horizontal wellbore. Since this was the first horizontal well drilled in the Clinton Sand interval, considerable knowledge and experience was gained in drilling and completing this well. The actual drilling operation required about 45 days of rig time. The well was stimulated during the summer/fall of 1994 and placed on production in early 1995.

The CW #14 was equipped with a pumping unit and downhole pump and has produced approximately 20,000 MCF of natural gas and 7,000 barrels of oil in its first full year of production. Unlike similar wells drilled in this area, the oil production is about twice that expected while the gas production is less than half of the neighboring offsets. Based on the production performance to date which has displayed a much shallower gas decline rate than a vertical well in the area, the CW #14 is currently estimated to have an ultimate recovery in the range of 330 to 400 MMCFE which is approximately 1.6 to 2.0 times its vertical offset wells.

While we are encouraged with the 1.6 to 2.0 increase in estimated ultimate recovery, horizontal drilling does not appear to be a viable economic alternative for primary development in this area without further improvements in reserve potential along with significant cost reductions. At this time, drilling this type well may be limited to special applications for secondary or enhanced oil recovery or perhaps for natural gas storage. The CW #14 horizontal drilling project, however, successfully demonstrated that the extremely hard and abrasive Clinton Sand can be horizontally drilled and stimulated which we considered a major technical accomplishment for drilling a well of this type in the Appalachian Basin.

Introduction

The Clinton Sand is a low permeable gas reservoir in Northeastern Ohio with initial well production generally in the 75 to 150 MCF per day and 5 to 10 barrels of oil per day. P. 203