RATING AND RANKING GEOLOGIC INTERVALS FOR NGL STORAGE APPLICATIONS IN THE TRI-STATE AREA

The Appalachian Oil & Natural Gas Research Consortium recently completed the Appalachian Storage Hub for Liquid Ethane Study (the Study) to identify potential storage reservoirs for natural gas liquids (NGLs) derived from the liquid-rich Marcellus and Utica shale plays in the tri-state area of Ohio, Pennsylvania and West Virginia. With publicly available data, survey geologists from the three states assessed three types of storage containers – mined-rock caverns in the Greenbrier Limestone, salt caverns in the Salina F4 salt and depleted siliciclastic gas reservoirs. To complete this Study, the research team needed to develop a method to rank the various intervals of interest. For every storage opportunity, the team applied numerical ratings (ranging from 0 to 3) to prospective areas based on a number of criteria including distance to infrastructure, average depth of the geologic interval, acreage, average net thickness, trap integrity, legacy well penetrations and stacked opportunities. Using data from the Midwest Regional Carbon Sequestration Project and other sources, the team applied more criteria to rate the depleted gas fields including pressure, average porosity, permeability, mode CO₂ storage, estimated cumulative gas production and working gas capacity. Storage opportunities were ranked by summing the ratings of each opportunity. To determine final rankings, the criteria were normalized by selecting the criteria common to all storage container types. The highest ranked storage opportunities include three Mississippian Greenbrier Limestone areas, two Silurian Salina salt cavern areas and four Devonian to Silurian depleted gas fields.