DEP Releases Data on Oil and Gas Well Structural Soundness
Program sets national standard in routine well monitoring to protect groundwater
Harrisburg, PA – The Department of Environmental Protection (DEP) has released the first four years of data on well structural soundness submitted by thousands of Pennsylvania oil and gas well operators. A comprehensive analysis of the first year, 2014, shows that the majority of wells in the state are being operated in a manner that greatly reduces the risk for groundwater impacts.
“Our Mechanical Integrity Assessment Program is the most rigorous routine well integrity assessment program to protect groundwater in the United States,” said DEP Secretary Patrick McDonnell. “We’re committed to protecting Pennsylvanians’ health, safety, and environment through continuous improvement of our regulatory oversight of the oil and gas industry.”
Unconventional and conventional operators are required to inspect wells on a quarterly basis for structural soundness to ensure that gas migration is prevented, leaks are managed, and groundwater is protected. They inspect wells for:
• Leaks outside the surface casing, which is the outermost casing layer around the well, designed to protect groundwater;
• Leaks outside the intermediate casing, which is the well casing intended to facilitate safe drilling of most shale gas wells to the depth where gas is found;
• Gas flows or pressures inside and outside the production casing, which is the deepest casing layer in the well;
• Escaping fluids (oil, gas, and saltwater); and
• Severe corrosion.
DEP reviews operators’ submitted data for potential problems and violations.
A comprehensive analysis (including file audits and independent site verification) of data submitted in 2014 showed that less than 1 percent of operator observations indicated the types of integrity problems, such as gas outside surface casing, that could allow gas to move beyond the well footprint. The movement of gas or other fluids beyond a well footprint has the greatest potential to result in environmental concerns.
About 30 percent of wells had gas present outside production casing. In some instances, this occurs due to an approved well design that allows for engineered vents. In a properly designed and operated well, gas is kept to the well footprint, and won’t flow into a water supply.
Operator compliance with mechanical integrity inspection requirements has been consistent since the program began, with reports submitted for approximately 99 percent of unconventional wells and about 50-60 percent of conventional wells. DEP district offices are actively working to improve the number of conventional operators who are in compliance. Those who remain out of compliance are individually responsible for a relatively small number of wells.
The Mechanical Integrity Assessment program has provided DEP district offices with useful information for identifying potential concerns at wells and more effectively assessing whether operator intervention is necessary to protect groundwater.
Some operators have introduced corrosion monitoring programs, become more proactive in plugging wells with depleted reserves, and improved the accuracy of their well inventories through coordination with DEP.