Well Construction Is Key To Overcoming 'Fracture Mania'

(Tech Connections Column, September 2011, American Oil and Gas Reporter)

The popular media, from newspapers to talk radio, frequently report on hydraulic fracturing as a “drilling process” in shale gas reservoirs, particularly the Marcellus formation.

Let me vent briefly about reporters who do not have 20 minutes to do an Internet search to learn that fracturing is a stimulation process, not a drilling process. There was a time when reporters did a little background research on topics they covered as due diligence, but the modern competitive pressures of journalism must no longer allow for that. Nevertheless, a quick look at FracFocus.org would help reporters understand the processes of drilling and completing a well. Unfortunately, the general public is now filled with an incorrect understanding of this industrial technology.

Massive hydraulic fracturing has its challenges, aspects of which have been described in this column. The public perception that the “drilling technology” of hydraulic fracturing is somehow related to reports of gas migrating into groundwater and water wells is unfounded.

I was pleased to note that the report issued in August by the secretary of energy’s blue ribbon Shale Gas Subcommittee (see story page 36) discounted hydraulic fracturing as a cause of methane leaking into groundwater systems. The report did call for more research into methane-tainted water supplies reported by Pennsylvania regulators, and said operators should develop (and follow) best practices for well design, indicating regulators should inspect wells at important points in the construction process.  

Those in the industry recognize that poor cementing is the likely culprit in any methane leaking to groundwater. That is what cementing is supposed to prevent. One effort to address methane leakage has been proposed as a supplement to the Environmentally Friendly Drilling Systems (EFDS) program managed by the Houston Advanced Research Center. HARC’s proposal is to conduct a joint industry project (JIP) to:
  • Analyze gas flow mechanics and sources in the Marcellus (and presumably Utica) Shale play;
  • Develop primary cementing procedures to prevent gas flow following cementing;
  • Analyze existing wells with surface pressure on the annulus to identify source and quantify flow, if any; and
  • Develop remedial methods for stopping gas leakage.
This is a challenging proposal, requiring a result that operators can use, regulators can trust, and the public can believe. Operators know that protecting the environment is their license to operate. The Gulf of Mexico blowout last year was ample demonstration of that.

There are indications of some failures in primary cementing. There are claims that gas has been migrating into freshwater zones and even to the surface up the casing annulus. The problem is multifaceted. The primary fix is to have cementing practices encompass adequate quality assurance and control to prevent any leaks from future wells. Diagnostics to identify gas source and flow behind pipe must be developed. Remediation technologies, including appropriate sealants to shut off any gas flow to groundwater, also are required.

While it is unlikely that Marcellus gas is migrating 6,000 feet, there are numerous shallow gas zones in the region. A big objective is to quantify the magnitude of the problem, then develop the analytical techniques to pinpoint the gas source in a leaking well and access it. Effective methods and materials to seal off the gas flow below groundwater must be developed and deployed. Lessons learned from controlling sustained casing pressure and gas migration from other regions, including the Gulf of Mexico and Alaska, might well be applicable to the Marcellus play.

This ambitious JIP will require the participation and support of many entities, including operators, regulators, service providers, technology developers, and others. DOE’s National Energy Technology Laboratory brings a wealth of knowledge and analytical skills directly applicable to this issue, as do a couple of other national laboratories. Numerous universities already involved in the EFDS program have applicable expertise as well.
 
CSI Technologies—a leading cementing technology company—Seal-Tite, which has developed technologies to detect and repair gas migration behind cemented pipe, the Ground Water Protection Council, NETL, and other EFDS participants could be leveraged, if the effort gains support. Those interested in the fledgling project can contact the Environmentally Friendly Drilling Systems Program (www.EFDSystems.org) for information.

The Environmental Protection Agency also is studying the gas leakage problem as well as other issues in the Marcellus Shale, including emissions into the atmosphere and surface water contamination.

As knowledge and technologies are developed, it is critical that state regulators review their oversight of industry operations and make adjustments to improve environmental performance. Ohio already mandates diagnostic assessment of cementing jobs, so it will be interesting to assess the success of cementing operations in Ohio as the Utica Shale play takes off. That should be an interesting source of data for any shale-gas leakage study.