(644c) Evaluation of Reinjection As a Means to Increase Petroleum Production from the Utica/Point Pleasant Unconventional Play: Impact of Reinjection Fluid Composition, Pressure, and Pore Size on Hydrocarbon Bubble Point Behavior

The development of U.S. unconventional resources has had a dramatic impact on global energy supply, with the U.S. becoming the world’s leading producer of petroleum and natural gas. This change has been beneficial to the public lowering energy prices, while increasing energy security. Unconventional (or shale) resources differ from conventional reservoirs, as these plays consist of interbedded carbonate and hydrocarbon containing shale layers consisting of micropore and mainly nanopore structures.

In such small pores, strong pore-fluid and fluid-fluid interactions exist which lead to complex fluid phase behavior. These pores experience increased capillary forces, electrostatic interactions, and surface chemistry (known as confinement) which cause hydrocarbon physical properties to deviate from their bulk. These forces result in less hydrocarbon productivity in comparison to larger pore structures of conventional reservoirs, resulting in a significant decline in unconventional well productivity. Methods which improve hydrocarbon recovery from unconventional reservoirs is of interest to industry, government, and the public as such technologies will reduce overall shale development efficiency.

Secondary treatments using chemical complexes (after hydraulic fracturing) are a potentially attractive methodology to increase hydrocarbon production from unconventional reservoirs. The Utica/Point Pleasant play of Eastern Ohio is particularly well positioned for such secondary chemical treatments as the play has several coal-fired power plants (which could supply CO₂) and produces significant quantities of natural gas (NG) containing natural gas liquids (NGLs). Both CO₂ and NG/NGLs reinjection could be used as a means to increase petroleum production from this important U.S. energy play.

Ohio University (OHIO) is investigating CO₂ and NG/NGLs reinjection as a means to increase petroleum production from unconventional resources, with a particular focus on the Utica/Point Pleasant play. This study is investigating hydrocarbon bubble point behavior in pores with and without confinement by simulating downhole conditions using a high pressure differential calorimeter (HP-DSC). This presentation will present results from this study including the influence of the pore size, pressure and reinjection fluid composition on the phase behavior of the hydrocarbons inside micro and nanopores. Further, HP-DSC results evaluating reinjection composition and pressure on bubble point behavior from Point Pleasant well core will also be presented.