Feasibility Investigation and Modeling Analysis of CO_2 Sequestration in Arbuckle Formation Utilizing Salt Water Disposal Wells

摘要

The rate of CO_2 production in many states, primarily from coal-fired power plants, is such that it only takes a few years to fill up any depleted oil and gas reservoirs. In order to reduce the level of CO_2 in the atmosphere and to minimize the cost of sequestration, the injection of CO_2 into aquifers utilizing disposal wells has been targeted. In this paper, an analysis of one particular case, namely, the Arbuckle formation in Oklahoma, was carried out to demonstrate its feasibility for CO_2 sequestration. First, a general review for CO_2 sequestration into aquifers utilizing existing disposal wells is presented. The limiting criteria for CO_2 sequestration in terms of the geology of the aquifer, lithology of the host rock, cost of operation, impact on reservoir properties, depth of the completed interval to maintain supercritical conditions for CO_2, injection pressure and rate to minimize gravity segregation, mobility ratio to prevent viscous fingering, and chemical interaction of aqueous and solid phases are discussed. Then, the existence of residual oil in the aquifer and its effect on reaction chemistry concerning the potential CO_2 sequestration applications in the Arbuckle formation are evaluated. This investigation was conducted by means of simulation of the prevailing processes. The cutoff points from dissolution to precipitation for each constituent in terms of different CO_2 injection rates were obtained by utilizing the simulation models gem-GHG and PHREEQC and were supported by a database of 150 disposal wells from which 25 wells were completed in the Arbuckle formation. We critically evaluate the current state of knowledge, identify areas needing research, and offer practical approaches for the evaluation of potential CO_2 sequestration sites using commercial disposal wells.