Potential Hazards of Horizontal Drilling and Recovery of Natural Gas & Oil from Tight Shale Formations in Areas of Historical Oil & Gas Development Moody and Associates, Inc. Timothy M. Eriksen, P.G.
Tight shales are now being developed in formations that were previously penetrated during historical, conventional development of deeper formations. The vertical components of unconventional wells, in some areas, penetrate oil and gas bearing formations that have been commercially produced. The migration of methane has occurred along migration pathways created by legacy oil and gas wells during unconventional oil and gas development. Though unconventional development nay not necessarily be the root cause of such incidents, they can be a trigger. These same migration pathways can also potentially serve as conduits for the migration of drilling fluids and produced waters.
Marcellus Shale Coalition figure
Drake s Oil Well 1859 First Gas Well 1821
Actual PA license plate available ONLY to the Friends of Drake Well
Pennsylvania s Regulatory History 1859 Colonel Drake s oil well 1955 Pennsylvania requires operators to report the locations of wells 1984 Oil & Gas Act First attempt at comprehensive oil & gas regulations Created the Abandoned and Orphaned Well Program If a well was still producing after 1979, the operator or owner was responsible for plugging the well. ~3,000 wells plugged under this program.
Legacy Wells in Pennsylvania 325,000 oil and gas wells drilled in Pennsylvania since 1859 120,000 wells have permits on file with the PADEP Over 200,000 oil and gas wells largely unaccounted for in Pennsylvania!!!!
Scott Detrow/StateImpact Pennsylvania Photo
StateImpact/Yan Lu figure
Abandonment of Legacy Wells Prior abandonments usually do not meet modern abandonment standards of state regulatory agencies or the industry. Creative abandonment using logs, brush, cannonballs or debris handy to the site at the time of abandonment.
Proposed Regulations (PA) Prior to hydraulically fracturing an unconventional well, the operator must identify the location of orphan or abandoned wells within 1,000 feet horizontally of the vertical well bore, and 1,000 feet measured from the surface above the entire length of the horizontal well bore.
Identification Methods Review of the PADEP s orphaned and abandoned well database. Review of applicable farm line maps, where accessible. Submittal of a questionnaire to landowners whose property is within the regulated area regarding the precise location of orphaned and abandoned wells on their property.
Those who operate in areas of historical development may want to consider protection of their assets by initiating a predrill plan beyond regulatory requirements.
Location of Undocumented Wells Using Geophysical Methods Magnetometer Measures changes in the earth s magnetic field caused by the presence of ferrous metallic material such as steel pipe and well casings. Electromagnetic methods Less sensitive than a magnetometer, but measures conductivity and magnetic susceptibility in the near subsurface. Useful when a metallic material is not suspected to be present (i.e. wood casings).
Either type of survey can be performed as a carried array or a towed array. Carried arrays can evaluate up to 5 acres per day. Towed arrays can evaluate up to 50 acres per day can be efficiently evaluated with a towed array. Little to no impact to land surface.
Timothy M. Eriksen, P.G. Moody and Associates, Inc. 685 Broad Street Extension Suite 1 Waverly, NY 14892 (607) 565-8800 teriksen@moody-s.com QUESTIONS?