Plugging Priority: Deciding Which Wells to Plug

Plugging orphaned and abandoned oil and gas wells is vital to efforts to slash methane emissions in the United States. However, a large portion of methane emissions come from about 10 percent of the thousands of known orphaned and abandoned wells. To get the most bang for their buck, plugging experts must be able to identify the types of wells that are most likely to have high methane emissions.

In a new paper, scientists at the U.S. Geological Survey (USGS)attempt to provide the insights needed to do just that. The study, published in the journal Science of the Total Environment, analyzed previous studies of orphaned and abandoned wells to better understand the sources of methane emissions and the wellbore conditions most often associated with leaking wells.

Sources and Conditions: Factors Associated with Methane Emitting Wells

The study authors used geochemical data from existing studies on orphaned and abandoned well methane emissions. By analyzing the types of isotopes found in methane from different wells, the researchers determined that the bulk of well emissions are thermogenic methane coming from oil and gas reservoirs. In contrast, the smallest contributor to emissions was biogenic methane produced by bacteria in wellbores and other areas. The second largest source of methane was gas from coal beds, which consisted of different amounts of thermogenic and biogenic methane.

The study also identified well conditions that could make transport of methane possible. They found that wellbore design, drilling technology and casing type used in the wells, and the age of the wells are major factors contributing to methane transport. Over time, wellbore materials and surface infrastructure can break down. Additionally, new networks of fractures in rock surrounding wellbores caused by natural seismicity or hydraulic fracturing of nearby wells can allow methane to reach the surface.

Find and Fix: Insights to Improve Emissions Estimates and Plugging Prioritization

This study yields a better understanding of the geologic and engineering factors involved in high-emitting orphaned and abandoned wells. With this information experts can identify areas likely to have such wells, improve estimates of methane emissions rates, and help guide efforts to target wells with the highest emissions.

Once they have identified wells emitting high volumes of methane, operators can make use of BioSqueeze’s growing suite of solutions to efficiently seal leaks. Unfortunately, many remediations prove ineffective due to limited planning and sealing technology not well suited for the application, resulting in repeat attempts and that put the project significantly over budget.

BioSqueeze provides a comprehensive solution that ensures leaks are sealed efficiently to maximize the effect of remediation efforts. The key to avoiding repeat attempts being success, which is achieved via a holistic review of the well/issue, Advanced Cement Imaging (ACI™) diagnostics to inform a remediation plan, and our innovative biomineralization technology capable of sealing leaks that no other technology can.