Experimental and Simulation Studies of Sequestration of Supercritical Carbon Dioxide in Depleted Gas Reservoirs

Abstract

Experimental, analytical, and simulation studies have been conducted to evaluate the feasibility of sequestering supercritical CO 2 in depleted gas reservoirs. The experimental runs involved the following steps. First, the 1 ft long by 1 in. diameter carbonate core is inserted into a viton Hassler sleeve and placed inside an aluminum coreholder that is then evacuated. Second, with or without connate water, the carbonate core is saturated with methane. Third, supercritical CO 2 is injected into the core with 300 psi overburden pressure. From the volume and composition of the produced gas measured by a wet test meter and a gas chromatograph, the recovery of methane at CO 2 breakthrough is determined. The core is scanned three times during an experimental run to determine core porosity and fluid saturation profile: at start of the run, at CO 2 breakthrough, and at the end of the run. Runs were made with various temperatures, 20°C (68°F) to 80°C (176°F), while the cell pressure is varied, from 500 psig (3.55 MPa) to 3000 psig (20.79 MPa) for each temperature.An analytical study of the experimental results has been also conducted to determine iv the dispersion coefficient of CO 2 using the convection-dispersion equation. The dispersion coefficient of CO 2 in methane is found to be relatively low, 0.01-0.3 cm 2 /min.Based on experimental and analytical results, a 3D simulation model of one eighth of a 5-spot pattern was constructed to evaluate injection of supercritical CO 2 under typical field conditions. The depleted gas reservoir is repressurized by CO 2 injection from 500 psi to its initial pressure 3,045 psi. Simulation results for 400 bbl/d CO 2 injection may be summarized as follows. First, a large amount of CO 2 is sequestered: (i) about 1.2 million tons in 29 years (0 % initial water saturation) to 0.78 million tons in 19 years (35 % initial water saturation) for 40-acre pattern, (ii) about 4.8 million tons in 112 years (0 % initial water saturation) to 3.1 million tons in 73 years (35 % initial water saturation) for 80-acre pattern. Second, a significant amount of natural gas is also produced: (i) about 1.2 BSCF or 74 % remaining GIP (0 % initial water saturation) to 0.78 BSCF or 66 % remaining GIP (35 % initial water saturation) for 40-acre pattern, (ii) about 4.5 BSCF or 64 % remaining GIP (0 % initial water saturation) to 2.97 BSCF or 62 % remaining GIP (35 % initial water saturation) for 80-acre pattern. This produced gas revenue could help defray the cost of CO 2 sequestration. In short, CO 2 sequestration in depleted gas reservoirs appears to be a win-win technology. v DEDICATION My graduate studies at Texas A&M University would not have been possible without the support and understanding of my wife and son. This dissertation is dedicated to: my wife, Eunsun Lee, my son: Eric Hyobin Seo, and to my parents, my father Soobeom Seo, my mother Dongsil Cho, and my grandmother for their support, love, prayer, and guidance. vi ACKNOWLEDGEMENTS I would like to express my deepest appreciation to my research advis...

CO2 Sequestration in a Depleted Gas Field: A Material Balance Study

“…Such an application would help improve the economics. SPE paper 81200 by Seo and Mamora (2003) also utilized reservoir simulation to study CO 2 injection in a thick gas reservoir and produce as much gas as possible before CO 2 breakthrough. The injected CO 2 will raise reservoir pressure, which in turn will increase hydrocarbon gas production by reactivating shut-in gas production wells.…”

“…Unlike Oldenburg and Benson (2002) and Seo and Mamora (2003), authors' investigation did not use reservoir simulation. That step will come later, if the client chooses to proceed further with the idea of injecting CO 2 into this depleted gas reservoir.…”

Reservoir Simulation of CO2 Storage in Deep Saline Aquifers

“…Several groups have reported aquifer-scale simulations of the storage process, usually in order to estimate the volume that can be stored. [1][2][3][4][5][6][7][8][9][10][11][12][13][14] Most schemes that have been put forward depend on storing CO 2 in the supercritical state. In these schemes, buoyancy forces will drive the injected CO 2 upward in the aquifer until a geological seal is reached.…”

Onset of Convection of CO-Sequestration in Deep Inclined Saline Aquifers

“…While there are uncertainties, the world's total capacity to store CO 2 deep underground is large [4] . They are generally unused and are available in many parts of the world [5] . It has been estimated that deep saline formations in the United States could potentially store up to 500 billion tones of CO 2 .…”