Abstract
This proposal is aimed at proving lower quality San Andres Reservoirs can be economically flooded by applying reservoir characterization and a combination of EOR methods that are not widely utilized. This site is representative of DOE Class II reservoirs and is uniquely suited for the successful application of advanced technology. The reservoir characterization methods will apply new technologies which include cross wellbore tomography, hydraulic fracture orientation detection, and 3D seismic. The intent of this proposal is to show that, using commercial resources available to all producers, oil remaining after waterflooding can be economically recovered using C02 flooding and Cyclic C02 stimulation in reservoirs more heterogeneous and of lower quality than current C02 projects.
Work proposed will begin with reservoir characterization using conventional geological and petrophysical methods incorporating 3D seismic and cross wellbore tomography. This characterization will be used in a compositional simulation study to provide production schedules for economic evaluation. The improved simulation model will be able to provide production forecasts for conventional miscible C02 flooding and provide the added benefits of forecasting recoveries from the Cyclic C02 stimulation and increased injection from fractured injection wells. The Cyclic C02 stimulation process provides an almost immediate production increase, and thus the quicker payouts needed to economically justify the large capital outlay required to bring C02 to the field. The ability to accurately provide forecast production during this early phase is essential to performing a realistic economic evaluation of the project. Another factor influencing C02 floods is unfavorable mobility ratios which cause poor sweep efficiency, thus processing only a small portion of the reservoir. Improving the sweep efficiency would increase recoveries by an estimated 1015% in the flood area.
This proposal is aimed at proving lower quality San Andres Reservoirs can be economically flooded by applying reservoir characterization and a combination of EOR methods that are not widely utilized. This site is representative of DOE Class II reservoirs and is uniquely suited for the successful application of advanced technology. The reservoir characterization methods will apply new technologies which include cross wellbore tomography, hydraulic fracture orientation detection, and 3D seismic. The intent of this proposal is to show that, using commercial resources available to all producers, oil remaining after waterflooding can be economically recovered using C02 flooding and Cyclic C02 stimulation in reservoirs more heterogeneous and of lower quality than current C02 projects.
Work proposed will begin with reservoir characterization using conventional geological and petrophysical methods incorporating 3D seismic and cross wellbore tomography. This characterization will be used in a compositional simulation study to provide production schedules for economic evaluation. The improved simulation model will be able to provide production forecasts for conventional miscible C02 flooding and provide the added benefits of forecasting recoveries from the Cyclic C02 stimulation and increased injection from fractured injection wells. The Cyclic C02 stimulation process provides an almost immediate production increase, and thus the quicker payouts needed to economically justify the large capital outlay required to bring C02 to the field. The ability to accurately provide forecast production during this early phase is essential to performing a realistic economic evaluation of the project. Another factor influencing C02 floods is unfavorable mobility ratios which cause poor sweep efficiency, thus processing only a small portion of the reservoir. Improving the sweep efficiency would increase recoveries by an estimated 1015% in the flood area.
Injecting C02 along a linear flood front via fractured injection wells would improve the areal sweep thereby increasing recovery. A linear flood would be obtained by lining up the fracture planes of injectors resulting from hydraulic fracture treatments along the injector rows and essentially connecting fracture wings to form the linear flood. This would increase injectivities and sweep efficiencies at a significantly lower cost than infill drilling.
This proposal will also address methods to improve the vertical sweep by the use of cross wellbore tomography in C02 tracking for WAG cycle optimization and mobility control. Recent work shows the effectiveness of mobility control agents for vertical sweep control, especially where thief zones are present. This project would attempt to address the sweep problems before C02 breakthrough and associated gas-handling problems occur by the use of tomography surveys and simulation to determine if this technology is cost effective for reservoir management.
Overall, this proposal will address 5 of the 6 identified primary producibility problems to show that a lower quality shallow shelf reservoir can economically recover additional oil by applying techniques available to all producers.
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