Air pollution
From Wikimarcellus
February 1, 2012 The solution to air pollution is ours
It seems almost self-evident that natural gas should be the favored fuel for the many types of engines that are used in natural gas exploration and development in the Marcellus and other shale plays. In terms of emitting lower air pollution, natural-gas-fueled engines are known to enjoy several advantages over diesel ones.
Drilling rig generators are generally diesel engines. Why can't these be powered by natural gas? Simply, until a well is actually producing, it may be difficult to get natural gas out to the well site in order to power these engines. Diesel engines are usually preferred, because diesel fuel can always be trucked in. Bi-fuel or dual-fuel engines have recently started to become available. These are turning the old diesel paradigm on its head, by providing clean-burning-natural-gas engines for drilling rigs, as well as helping company bottom lines by allowing them to use some of the field gas produced on a well site, and thus greatly lowering the overall cost of trucking in diesel for engine fuel.
Gti-bi
GTI Bi-fuel unit (Photo courtesty of ECO AFS and Altronic, Inc.)
No engine manufacturer presently makes a bi-fuel engine for use in drilling operations. However, an aftermarket kit is available from GTI Bi-fuel, a subsidiary of Altronic, Inc. that does the job. There may be other ones out there like it, but I'm only familiar with GTI Bi-fuel's product at the moment.
It should be noted that natural gas is already preferred as fuel in gas processing plants and compressor stations where refined gas is readily available to be used as fuel. However, on well sites, frequently only field gas direct from the well is available, and until recently bi-fuel engines were not available to handle the inconsistent and irregular nature of field gas when used as fuel. Some capacity to burn diesel oil is always needed as backup when the natural gas supply is insufficient. With the growth of the Marcellus shale play of Pennsylvania and West Virginia more gas pipeline infrastructure is becoming available, thus more readily providing supplies of high quality natural gas. Pipeines can supply both straight gas-fired as well as bi-fuel rig engines.
One of the big environmental benefits of using field gas to fuel rig operations is that there are never any smelly plumes of black diesel exhaust. It also means reductions in NOx (oxides of Nitrogen), CO2 (carbon dioxide), CO (carbon monoxide), VOCs (volatile organic compounds) and overall particulate matter. When field gas is used, it results in a great savings to the operator, amounting to a savings of up to 70% over diesel. There is also less impact on local communities as diesel tanker truck traffic can also be reduced. For example, Encana reported that one of its gas-fired rigs in the Jonah Field in Wyoming was able to achieve annual reductions of 600 tons of NOx and 4,000 tons of VOC emissions. In addition, natural gas engines are much quieter to operate than are diesel ones.
As with the introduction of any new technologies, there have been some issues with the bi-fuel engines. These include inconsistency, unexpected blackouts, and performance. Some of these are related to the quality of field gas feed, and some to the lack of training crews in fine-tuning the engines. Preston_hale Bi-fuel powered Marcellus shale rig. Greene Co., PA (Photo courtesy of Preston Hale and ECA)
Case studies:
Energy Corp. of America and Payne International Drilling Contractors (H&P) Marcellus shale well in Greene Co., PA
Williams and rig owner, Felderhoff, in the Barnett shale
Encana and rig designer/owner, Ensign Energy Services, in the Jonah Field in southwest Wyoming
Resources:
Armendariz, Al, "Emissions from Natural Gas Production in the Barnett Shale Area and Opportunities for Cost-Effective Improvements" , Environmental Defense Fund, Version 1.1, January 26, 2009, Accessed February 1, 2012.
ecoafs.com, "Video footage of drilling rig and diesel generator operating on 40% to 60% well gas in North Dakota oil field.", Accessed February 1, 2012.
gti-aci.com, "The GTI Bi-Fuel System from Altronic" , Accessed February 1, 2012.
Hill, David, "Encana Initiative Underscores Environmental, Economic Benefits Of Powering Rigs On Natural Gas" , The American Oil & Gas Reporter, August, 2011, Accessed February 1, 2012
