--> Abstract: Optimizing Co2 Injections for Both Seal Integrity and Economic Return, by Timothy Meckel and Nishanth Kalyanaraman; #90078 (2008)

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Optimizing CO2 Injections for Both Seal Integrity and Economic Return

Timothy Meckel and Nishanth Kalyanaraman
Gulf Coast Carbon Center, Bureau of Economic Geology, The University of Texas at Austin, Austin, TX

Industrial CO2 sequestration projects require the convergence of economic incentives, favorable geologic conditions, and regulatory policy. In some cases, conflicts arise. For example, there is a regulatory requirement to maintain injections below a maximum injection pressure, which is limited by geologic conditions (seal capillary entry pressure, hydraulic fracturing). Yet there are economic advantages to maintaining high injection rates (larger volumes stored per unit time), resulting in incentives to accept more geologic risk (higher overpressure, higher leakage risk). Low injection rates are geologically less risky (lower overpressure, less potential leakage) but may be less attractive from an economic perspective, mainly due to the longer injection periods. Each injection scenario has a specific economic return and risk of leakage.

Our research reconciles geologic and regulatory limitations with the variable economic consequences of different injection scenarios to identify the optimal injection strategy for a given geology. Using numerical codes adapted from the natural gas storage industry, we evaluate the influence that the rate of pressure buildup has on vertical CO2 migration rates and net storage. For each pressure buildup scenario, a basic economic model including capital and operational expenses is used to determine annual profit (tax credit minus expenses). Net profit and net storage results for each complete project are compared for different geologic and injection scenarios, focusing on the optimization of injection rates (pressure buildup through time) for both seal integrity (maximum net storage, leak minimization) and economic return (minimum cost). Integrating these competing motivations provides practical guidance for initiating (or continuing) a sequestration project in an identified geologic setting and regulatory situation.

 

AAPG Search and Discover Article #90078©2008 AAPG Annual Convention, San Antonio, Texas