Gas Well Integrity and Associated Gas Migration Investigations in the Marcellus Shale

Abstract

The Marcellus Shale is one of the largest natural gas fields in the world and has been the site of a massive natural gas development effort involving hundreds of oil and gas companies. With the onslaught of the “shale revolution,” developers moved into states like Pennsylvania and began drilling/completing natural gas wells by the hundreds. This development occurred so rapidly that attention to issues such as wellbore natural gas intrusion was not initially given the priority it demanded in all cases. This led to instances of alleged natural gas migration and impacts to groundwater supplies in several areas of the region. Although there has been an onslaught ofevaluations geared toward the study of groundwater contamination, the author has researched the natural gaswells themselves. Based on thousands of wellbore integrity studies in the Marcellus and other worldwide shale regions, this paper will summarize the forensic processes, analysis methods, and approaches used in assessing wellbore integrity as part of a natural gas migration investigation. The paper will also present details that pertain to remedial alternatives and approaches to wells requiring attention.