Fluid Substitution Modeling to Determine Sensitivity of 3D Vertical Seismic Profile Data to Injected CO­2­ at an active Carbon Capture, Utilization and Storage Project, Farnsworth field, TX.

Abstract:

The Southwest Regional Partnership on Carbon Sequestration monitors a CO₂ capture, utilization and storage project at Farnsworth field, TX. The reservoir interval is a Morrowan age fluvial sand deposited in an incised valley. The sands are between 10 to 25m thick and located about 2800m below the surface. Primary oil recovery began in 1958 and by the late 1960’s secondary recovery through waterflooding was underway. In 2009, Chaparral Energy began tertiary recovery using 100% anthropogenic CO₂ sourced from an ethanol and a fertilizer plant. This constitutes carbon sequestration and fulfills the DOE’s initiative to determine the best approach to permanent carbon storage.

One purpose of the study is to understand CO­₂ migration from injection wells. CO_2­ plume spatial distribution for this project is analyzed with the use of time-lapse 3D vertical seismic profiles centered on CO₂ injection wells. They monitor raypaths traveling in a single direction compared to surface seismic surveys with raypaths traveling in both directions. 3D VSP surveys can image up to 1.5km away from the well of interest, exceeding regulatory requirements for maximum plume extent by a factor of two. To optimize the timing of repeat VSP acquisition, the sensitivity of the 3D VSP surveys to CO₂ injection was analyzed to determine at what injection volumes a seismic response to the injected CO­₂ will be observable. Static geologic models were generated for pre-CO₂ and post-CO₂ reservoir states through construction of fine scale seismic based geologic models, which were then history matched via flow simulations. These generated static states of the model, where CO_2­ replaces oil and brine in pore spaces, allow for generation of impedance volumes which when convolved with a representative wavelet generate synthetic seismic volumes used in the sensitivity analysis.

Funding for the project is provided by DOE’s National Energy Technology Laboratory (NETL) under Award No. DE-FC26-05NT42591.