CO2 SEQUESTRATION POTENTIAL OF TEXAS LOW-RANK COALS

The objectives of this project are to evaluate the feasibility of carbon dioxide (CO{sub 2}) sequestration in Texas low-rank coals and to determine the potential for enhanced coalbed methane (CBM) recovery as an added benefit of sequestration. The primary objectives for this reporting period were to construct a coal geological model for reservoir analysis and to continue modeling studies of CO{sub 2} sequestration performance in coalbed methane reservoirs under various operational conditions. Detailed correlation of coal zones is important for reservoir analysis and modeling. Therefore, we interpreted and created isopleth maps of coal occurrences, and correlated individual coal seams within the coal bearing subdivisions of the Wilcox Group--the Hooper, Simsboro and Calvert Bluff formations. Preliminary modeling studies were run to determine if gravity effects would affect the performance of CO{sub 2} sequestration in coalbed methane reservoirs. Results indicated that gravity could adversely affect sweep efficiency and, thus, volumes of CO{sub 2} sequestered and methane produced in thick, vertically continuous coals. Preliminary modeling studies were also run to determine the effect of injection gas composition on sequestration in low-rank coalbeds. Injected gas composition was varied from pure CO{sub 2} to pure N{sub 2}, and results show that increasing N{sub 2} content degrades CO{sub 2} sequestration and methane production performance. We have reached a Data Exchange Agreement with Anadarko Petroleum Corporation. We are currently incorporating the Anadarko data into our work, and expect these data to greatly enhance the accuracy and value of our studies