Haynesville Shale—A Primer
Guest Authors: Brian Bohm, P.G., ALL Consulting; Teri S. Holmes, M.S., ALL Consulting


The Haynesville Shale
Encompassing approximately 9,000 square miles in northern Louisiana and eastern Texas, the Haynesville Shale has an average thickness of 200 feet to 300 feet. Current predictions for the Haynesville Shale have 251 Tcf of technically recoverable resources with a total estimate of 717 Tcf of original gas-in-place, shale gas volumes which are rivaled only by the Marcellus Shale Play which covers a significantly larger geographic area of 95,000 square miles (DOE, 2009). “Technically recoverable resources” refers to the estimated total amount of gas considered recoverable with current technology regardless of cost while “original gas-in-place” refers to the estimated total volume of gas contained within the reservoir regardless of whether it can be recovered (DOE, 2009).

The 100 million-year-old Haynesville Shale gas formation lies approximately 10,500 ft. to 13, 500 ft. below the surface. Until recent advances in horizontal drilling and hydraulic fracturing technology, along with rising natural gas prices, the gas reserves the Haynesville Shale holds would have been technologically and economically unrecoverable (DOE, 2009). While current economic conditions have slowed the exploration and development of the Haynesville Shale, expectations are that activity will be similar to that of the neighboring Barnett Shale of northeast Texas (Dallas-Ft. Worth area). As such, concerns regarding environmental impacts from hydraulic fracturing and produced water are expected to become more prevalent, particularly in regard to water resources and the responsible use of water resources. Experience in the Barnett Shale Gas Play, and to some extent, the Marcellus and Fayetteville Gas Plays, has provided a wealth of knowledge, information and technological advances to address those concerns.

Drilling and fracturing
Both vertical and horizontal wells are used in shale gas drilling and completion; however, horizontal wells are the increasing trend due to both environmental concerns and economic efficiency (DOE, 2009). Horizontal drilling allows more exposure within the formation to optimize capture of natural gas as well as reducing the environmental footprint of drilling activity (DOE, 2009). The United States Department of Energy’s recently released document on shale gas development in the United States explains that “a vertical well may be exposed to as little as 50 ft of formation while a horizontal well may have a lateral wellbore extending in length from 2,000 to 6,000 ft within the 50-300 ft thick formation” (DOE, 2009, p.47). As such, surface disturbance and impacts to wildlife and communities are reduced while providing optimal gas recovery; considering 16 vertical wells per 640-acre section of land would disturb 77 acres, the equivalent in horizontal wells (4- horizontal wells) would disturb approximately 7.4 acres (DOE, 2009). In addition to reductions in surface disturbance, horizontal wells allow for development in areas previously considered unavailable, primarily urban and environmentally sensitive or protected areas. Well pads can be located away, or ‘setback’, from residences, roadways, wildlife habitats and other protected areas without hampering access to available gas reserves.

In order to recover the shale gas after drilling a well, current industry practice is to hydraulic fracture the formation to stimulate the near wellbore area and facilitate the release of natural gas trapped within the shale. Hydraulic fracturing is a process whereby a fracturing fluid, primarily water, is pumped into the formation under pressure at a calculated rate to form fractures and cracks within the formation, providing a pathway for the gas to migrate to the wellhead for recovery. Sand or other granular materials are added to the fracturing fluid to help ‘prop’ open the newly created fractures after the fluid has been removed from the formation (ALL, 2008a). Additional chemicals may be added to the fracturing fluid for specific engineering purposes; these additions may include friction-reducing agents, biocides and various stabilizers to prevent corrosion of metal piping in the well (DOE, 2009; ALL, 2008a). Depending on the formation and well characteristics, multiple fracturing procedures may be performed in order to fully develop the well for gas recovery (DOE, 2009). While each well and geologic formation is unique, continuing advances in horizontal drilling and well completion practices provide additional reductions in environmental impacts from oil and gas activities while providing the nation’s critical energy supply.

For more info visit www.all-llc.com.

Or

ALL Consulting
1718 S. Cheyenne Ave.
Tulsa, OK 74119
phone: 918-382-7581


Part 3 will discuss Water Management and Regulation and will be up on Tuesday, May 26th