Current Gas Well Completion Practices In Appalachian Gas Sands
Authors: Gwinn James E. , McManus George R. 
Published: December 2007

This paper discusses the current completion practices of the major shallow gas-bearing reservoirs practices of the major shallow gas-bearing reservoirs and some of their characteristics in Pennsylvania, Ohio and West Virginia. This will include a description of the drilling, casing, perforating, stimulation, logging and cementing procedures.

These sands are the Big Injun, Berea, Bradford Group, Benson and Clinton.

Introduction

The natural open flow of these sands are seldom of economic quantities and are always stimulated in some manner. Methods of treating multiple-sand zones in the Bradford Group gas wells and different stimulation treatments used in these various formations are explained. The results of stimulation are successful both economically and mechanically in the greater number of wells drilled.

The Clinton sand is the major producing formation in Ohio; the Big Injun, Benson and Berea formations are major producers in West Virginia, while the Bradford sand group is a major producing group in Pennsylvania. The Bradford group includes the following Pennsylvania. The Bradford group includes the following producing formations: Kane, Third, Second and First producing formations: Kane, Third, Second and First Bradford, Sheffield, Balltown, Tiona, Speechley and Warren Sands.

DESCRIPTION OF SANDS AND PRODUCING AREAS

The Clinton sand is found throughout most of Ohio and at depths of 3000 to 6000 feet. The gross formation height will vary from 45 to 150 feet. Net formation is 5 to 80 feet in height. Porosity will range from less than 7 percent up to 12 percent. Permeability can be as low as 0.1 millidarcy to a Permeability can be as low as 0.1 millidarcy to a as 1 millidarcy.

The Bradford group is found throughout central and northern Pennsylvania. The vertical height of this group is 1000 to 1200 feet. The individual sands can range from 10 to 60 gross feet with a net thickness of 10 to 30 feet. The overall porosity is 8 percent and have less than 1 millidarcy of permeability percent and have less than 1 millidarcy of permeability The average total depth of these wells is 3600 feet. Three or four sands are usually stimulated in a single well. Natural open flows are extremely low.

The Benson sand is most productive in the North-Central part of West Virginia and is extremely fine grained. The gross height will range from 5 to 30 feet and the net height from 2 to 20 feet. Porosity will be 6 to 12 percent and has permeabilities less than one millidarcy.

The Big Injun formation is found throughout most of West Virginia and can be a sandy dolomite, calcareous sand, fine grain sandstone or coarse grain sandstone and with solubilities from zero to over 60 percent. These variations in lithology cause great percent. These variations in lithology cause great changes in stimulation designs. The Big Injun can produce both gas and oil, gas, or oil. produce both gas and oil, gas, or oil. The gross height is 30 to 100 feet and net height 8 to 30 feet. Porosity is usually between 8 to 20 percent and permeabilities of one millidarcy or less. percent and permeabilities of one millidarcy or less. The Berea sand is found over all of Southern and Central West Virginia. It is both a gas producer and in some areas an oil producer. The gross height is 30 to 50 feet and the net height is 10 to 14 feet. Porosity will range from 8 to 16 percent with Porosity will range from 8 to 16 percent with permeabilities of less than one millidarcy. permeabilities of less than one millidarcy.

DESCRIPTION OF DRILLING EQUIPMENT

Drilling equipment being used to drill the Appalachian gas sand wells is almost exclusively air rotary. Some fluid drilling does exist in certain areas such as Southern Ohio where the Berea sand is being drilled with fluid. However, cable tools can be found operating in most all active drilling areas.