On March 9, 2012, the Ohio Department of Natural Resources (DNR) issued a preliminary report summarizing its findings as to the relationship between a series of low-magnitude earthquakes near Youngstown, Ohio (that culminated in a December 31, 2011 4.0-magnitude seismic event) and the operation since late 2010 of a class II deep injection well near a fault line in the area. In the report DNR clearly noted that such a direct link is very rare and that a number of separate circumstances must coincide for an injection well to induce an earthquake. Nonetheless, DNR concluded in the report that a “number of coincidental circumstances appear to make a compelling argument for the recent Youngstown-area seismic events to have been induced [by operation of the injection well].”
At the end of its report, DNR announced key details concerning the substance of the agency’s proposed revisions to its regulations as to class II injection wells. DNR has been drafting these revised regulations for the past few months and intends to release them shortly, but the report summarized the substance of these forthcoming regulations. DNR’s proposed regulations will:
- Require a review of existing geologic data for known faulted areas within the state and avoid the locating of new Class II disposal wells within these areas;
- Require of a complete suite of geophysical logs (including, at a minimum, gamma ray, compensated density-neutron, and resistivity logs) to be run on newly drilled Class II disposal wells. A copy of the completed log, with analytical interpretation will be submitted to DNR;
- Evaluate the potential for conducting seismic surveys;
- Require operators to plug back with cement, prior to injection, any well drilled in Precambrian basement rock for testing purposes.
- Require the submission, at time of permit application, of any information available concerning the existence of known geological faults within a specified distance of the proposed well location, and submission of a plan for monitoring any seismic activity that may occur;
- Require a measurement or calculation of original downhole reservoir pressure prior to initial injection;
- Require conducting a step-rate injection test to establish formation parting pressure and injection rates;
- Requires the installation of a continuous pressure monitoring system, with results being electronically available to DNR for review;
- Require the installation of an automatic shut-off system set to operate if the fluid injection pressure exceeds a maximum pressure set by DNR; and
- Require the installation of an electronic data recording system for purposes of tracking all fluids brought by a brine transporter for injection.
DNR is considering these changes to deep Cambrian-Precambrian Class II injection wells either through specialized attached permit conditions or through potential changes to DNR’s well regulations. This blog will provide a summary of the final proposed regulations once DNR releases them, and will update this item once DNR releases its final report on the Youngstown seismic events.