SIMPLE ESTIMATION METHODOLOGY OF LEAKAGE FROM GEOLOGIC STORAGE OF CO_2

摘要

The objective of this paper is to develop a simple methodology to estimate amount of such leakages, which can be utilized by those who do not have sufficient simulation resources, in order to create a basis for CCS accounting. We develop leak estimation methodology based on quality of cap rocks (seal quality). To quantify quality of cap rocks, we newly developed Cap-rock Quality Factors (CQF). CQF is calculated reflecting features of site, height of cap rock, depth of the site and possibility of three types of leakage, leakage via matrix of cap-rock, leakage via fracture of cap-rock, and leakage via wells. We use two different interpretations of CQF, Conduit Model and Membrane Model, to estimate amount of leakage by category of cap-rock (seal) quality. Conduit Model can be generally applicable to "certain structural seal" category and Membrane Model applicable to "uncertain seal" category.rnThe methodology can provide the first order estimate of leakage of classified geologic storage of CO_2, which would be a basis for developing accounting methodology. In particular, this is intended to contribute to accounting rules for CCS proposed by our research project. Moreover, project planners and policy makers would utilize the methodology to examine the feasibility of some CO_2 geologic storage projects.