MRCSP has employed a so-called “piggyback” strategy to cost-effectively gain insight into the geologically complex regional area. This strategy helps to overcome two problems. On the one hand, using existing and publicly-available geologic data provides a low-cost source geologic data, but it may not be complete and it can be decades-old. On the other hand, drilling new wells solely for the purposes of site screening and selection is cost prohibitive over an expansive geographic region with discontinuous geologic formations and attributes as in the MRCSP region. With its piggyback strategy, MRCSP is combining all available historical data with data from new commercial wells that have advanced geologic data. This method provides extensive coverage from the existing data and high-quality localized data. In order to expand geologic datasets more cost effectively, wells being drilled for commercial purposes are selected for piggyback opportunities. In this approach, MRCSP funds the collection of advanced datasets during or after drilling, which can include basic and advanced logs, whole core and sidewall cores, flowmeter data, and injection testing. The data collected is beneficial both to the well operator (who would not normally collect advanced data) and to the MRCSP project proponents.
MRCSP is using the data from piggyback locations combined with the large existing dataset generated by older oil and gas exploration to identify potential storage reservoirs along with corresponding cap-rock formations. Well data from the states of Ohio, Michigan, Kentucky, West Virginia and Pennsylvania are being studied to characterize a complex region along the Ohio River Valley to locate potential storage sites. Key steps in the research include: systematic analysis of existing well log and seismic data to identify potential reservoirs and corresponding sealing formations; participation in piggyback wells to cost-effectively gather new data; using the advanced geologic data from new wireline logs and core to correlate new data with historically available data; detailed geologic analysis to assess regional extent; and reservoir modeling to estimate capacity and injectivity. In addition to evaluating formations suitable for receiving and storing injected CO₂, the research also investigates overlying formations that provide barriers to prevent upward migration of CO₂ out of the reservoirs.
During Phase II, one of the piggyback tests was the Ohio Stratigraphic Borehole Project (Ohio Strat Test) that took place in the spring of 2007 at a site in Tuscarawas County, Ohio. A team of scientists from the Ohio Department of Natural Resources (ODNR) and Battelle collaborated to drill a well to a depth of 8,600 feet and conduct a series of tests in the well. This test did not involve injecting any CO₂, but rather was used to further characterize the rock properties in the deep layers. Click here
for information about this test from the ODNR Division of Geological Survey web site. Click here for the final report on the results.