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Title: Impact of layer thickness and well orientation on caprock integrity for geologic carbon storage

Economic feasibility of geologic carbon storage demands sustaining large storage rates without damaging caprock seals. Reactivation of pre-existing or newly formed fractures may provide a leakage pathway across caprock layers. In this paper, we apply an equivalent continuum approach within a finite element framework to model the fluid-pressure-induced reactivation of pre-existing fractures within the caprock, during high-rate injection of super-critical CO 2 into a brine-saturated reservoir in a hypothetical system, using realistic geomechanical and fluid properties. We investigate the impact of reservoir to caprock layer thickness, wellbore orientation, and injection rate on overall performance of the system with respect to caprock failure and leakage. We find that vertical wells result in locally higher reservoir pressures relative to horizontal injection wells for the same injection rate, with high pressure inducing caprock leakage along reactivated opening-mode fractures in the caprock. After prolonged injection, leakage along reactivated fractures in the caprock is always higher for vertical than horizontal injection wells. Furthermore, we find that low ratios of reservoir to caprock thickness favor high excess pressure and thus fracture reactivation in the caprock. Finally, injection into thick reservoir units thus lowers the risk associated with CO 2 leakage.
Authors:
 [1] ;  [1] ;  [2]
  1. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Engineering Sciences Center
  2. Univ. of Texas, Austin, TX (United States). Jackson School of Geosciences. Bureau of Economic Geology
Publication Date:
Report Number(s):
SAND2016-3923J
Journal ID: ISSN 0920-4105; PII: S092041051630300X
Grant/Contract Number:
AC04-94AL85000; FE0023316; SC0001114
Type:
Accepted Manuscript
Journal Name:
Journal of Petroleum Science and Engineering
Additional Journal Information:
Journal Volume: 155; Journal ID: ISSN 0920-4105
Publisher:
Elsevier
Research Org:
Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Univ. of Texas, Austin, TX (United States)
Sponsoring Org:
USDOE Office of Fossil Energy (FE), Oil and Natural Gas (FE-30); USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); USDOE National Nuclear Security Administration (NNSA)
Contributing Orgs:
Univ. of Texas, Austin, TX (United States)
Country of Publication:
United States
Language:
English
Subject:
58 GEOSCIENCES; Fracture; Geomechanics; Geological CO2 sequestration; Multiphysics
OSTI Identifier:
1340243
Alternate Identifier(s):
OSTI ID: 1461959