Coupled Hydrodynamic-Geomechanical Modelling of CO2-WAG Field Development at Farnsworth Unit: A Case Study

Abstract

The SWP project is located in a mature waterflood undergoing conversion to CO2-WAG operations at Farnsworth, Texas, USA. Utilized CO2 is anthropogenic, sourced from a fertilizer and an ethanol plant. Major project goals are optimizing the storage/production balance, ensuring storage permanence, and developing best practices for CCUS. This paper provides a review of work performed toward development of a 3D coupled Mechanical Earth Model (MEM) for use in assessment of caprock integrity, fault reactivation potential, and evaluation of stress dependent permeability in reservoir forecasting. Mechanical property estimates computed from geophysical logs at selected wellbores were integrated with 3D seismic elastic inversion products to create a 3D "static" mechanical property model sharing the same geological framework as the existing reservoir simulation model including 3 major faults. Stresses in the MEM were initialized from wellbore stress estimates and reservoir simulation pore pressures. One way and two way coupled simulations were performed using a compositional hydrodynamic flow model and geomechanical solvers. Coupled simulations were performed on history matched primary, secondary (waterflood), and tertiary (CO2 WAG) recovery periods, as well as an optimized WAG prediction period. These simulations suggest that the field has been operating at conditions which are not conducive to either caprock failure or fault reactivation. Two way coupled simulations were performed in which permeability was periodically updated as a function of volumetric strain using the Kozeny-Carmen porosity-permeability relationship. These simulations illustrate the importance of frequent permeability updating when recovery scenarios result in large pressure changes such as in field re-pressurization through waterflood after a long primary depletion recovery period. Conversely, production forecasting results are less sensitive to permeability update frequency when pressure cycles are short and shallow as in WAG cycles. This paper describes initial work on development of a mechanical earth model for use in assessment of geomechanical risks associated with CCUS operations at FWU. The emphasis of this work is on integration of available geomechanical data for creation of the static mechanical property model. Preliminary coupled hydro-mechanical simulations are presented to illustrate some of the key diagnostic output from coupled simulations which will be used in later work for in depth evaluation of specific risk factors such as induced seismicity and caprock integrity.

Assessment of chemo-mechanical impacts of CO2 sequestration on the caprock formation in Farnsworth oil field, Texas

“…The mineral precipitation and dissolution reactions were governed by Eqs. (11)(12)(13) according to Nghiem et al 44 and Nghiem et al 45 .…”

“…According to Benson 7 , to avoid significant damage to the environment and ecosystems, the CO 2 levels in the atmosphere need to be reduced and stabilized in the next couple of years. To achieve a reduction in the atmospheric CO 2 emission, geologic storage, via the Carbon Capture and Storage (CCS) and Carbon Capture, Utilization, and Storage (CCUS) technologies, has been one of the promising methods for CO 2 storage [8][9][10][11][12][13] . Nevertheless, the long-term storage and safety of the sequestered CO 2 in the geological formations is critical since the injected CO 2 could have the potential to escape from the target storage formation to shallower formations and eventually be released back into the atmosphere.…”

Simulation study of chemo‐mechanical impacts of CO2injection in morrow b sandstone reservoir

“…However, the work of Kutsienyo et al 44 and Sun et al 26 only coupled hydrodynamics and geochemistry. McMillan et al 46,47 used coupled hydrodynamical and geomechanical simulation models to evaluate the integrity of the caprock at FWU, finding that field operation conditions did not threaten the caprock integrity or trigger fault reactivation.…”

Time‐lapse VSP integration and calibration of subsurface stress field utilizing machine learning approaches: A case study of the morrow B formation, FWU

“…Several publications on the calibration of a coupled hydro-mechanical model using attributes computed from a VSP dataset have been found. 13,[19][20][21] Attributes such as the seismic wave travel times, velocities, amplitudes, and seismic reflectivity have been utilized to update reservoir flow properties and monitor the preferential fluid movement. 4,5,11,22 For instance, In Salah, a well-known CCUS project in Algeria has CO 2 stripped from produced natural gas and reinjected into the Krebka formations' aquifer leg.…”