CO2 capture and sequestration- A solution for enhanced recoveries of unconventional gasses and liquids

The consequences of increase in CO2 concentration in atmosphere are well known to scientists, politicians and policy makers. These effects can be foreseen in near future, bringing a serious concern and responsibility to the research community to find efficient and potential solutions to deal with it. Furthermore, use of fossils to fulfill the extensive energy requirements worldwide is majorly responsible for rapidly rising CO2 levels. Therefore, CO2 capture in unconventional reservoirs by injection and displacement of oil and gas either in supercritical state or liquid state is a potential method to permanently capture a significant volume of CO2. In larger picture, this strategy can substantially contribute in the mitigation of global warning. This review presents some useful aspects of CO2 sequestration in unconventional reservoirs i.e. in form of gas hydrates, shale reservoirs and in coalbeds. Here we explain in-depth mechanisms involved in gas production, adsorption/desorption, diffusion, gas migration and expansion/shrinkage in a given matrix. The review also includes the pathways involved in displacement of oil and gas by CO2, challenges involved in this process and how enhanced recovery of oil and gas can be achieved. This process solves the following challenges worldwide (i) rising levels of CO2, (ii) continuous rise in energy demand (iii) replacement of limited conventional resources (iv) worldwide distribution of unconventional reservoirs (v) eliminating the geopolitical conflicts with minimal harmful effects towards environmental and human health. This review presents collective information about the parameters responsible for enhanced oil and gas recovery.