Continuous Real-Time Pressure Monitoring during a Co₂-EOR Project from Cranfield, Ms and Relevance for Geologic Sequestration

Meckel, Tip ¹; Hovorka, Susan ¹; Trevino, Ramon H.^1
1 The University of Texas at Austin, Bureau of Economic Geology, Austin, TX.

Elevated formation fluid pressure resulting from large-volume carbon dioxide (CO₂) injection for sequestration is a key factor affecting storage integrity (seal and well performance) and ultimate capacity. Monitoring pressure dynamics (buildup and falloff) is a fundamental and relatively inexpensive and pragmatic technique for monitoring storage performance. The Southeast Regional Carbon Sequestration Partnership (SECARB) field project conducted by the Gulf Coast Carbon Center with support from the National Energy Technology Laboratory (NETL) and the U.S. Department of Energy (DOE) and managed by the Southern States Energy Board (SSEB) at Denbury Resources’ Cranfield Field in southwest Mississippi provides a unique opportunity to monitor large-scale (10⁵-10⁶ tons) CO₂ injection on the flank of an anticline at 3 km depth. The reservoir has been shut-in for decades and was near hydrostatic pressures when injection commenced. Thus, the initial pressure buildup prior to production is similar to what would be expected for many brine sequestration projects. The evolving CO₂ distribution and pressure perturbation has been monitored since July 2008 by a combination of time-lapse field-wide pressure and saturation well logging. A novel aspect of the monitoring design focuses on real-time pressure and temperature evolution in a dedicated observation well, combining observations from both the injection interval and a monitoring interval 120 m higher (dual completion) for early detection of unanticipated fluid migration out of the injection zone via wellbores or confining system. These data are integrated to constrain and refine numerical flow simulations with a focus on pressure history matching and CO₂ distribution in the context of sequestration performance.

AAPG Search and Discovery Article #90090©2009 AAPG Annual Convention and Exhibition, Denver, Colorado, June 7-10, 2009