Abstract
The investigation into the combined processes of CO2-EOR and geologic carbon sequestration was seen to be a viable solution to reducing CO2 emissions from the atmosphere, while boosting production from mature oil fields. However, the practicality of the combined process hinges on the determination of an optimum injection pressure to maximize the application of both methods. In addition, the success of these two operations is also contingent upon the dynamic sealing capacity of bounding faults, to allow hydrocarbon accumulation and trapping of injected CO2. Consequentially, the goal of this research is to optimize the implementation of combined CO2-EOR with simultaneous CO2 sequestration and investigate the enhancing/diminishing aspects of fault reactivation and CO2 migration. The study was approached from two scenarios; the first was the determination of an optimum injection pressure for the combined process, with the main focus on maximizing recovery from a mature oil field. The results saw a maximum cumulative recovery of 73.7090 Mbbls being facilitated at an optimal injection rate of 722 Scf/day. The second scenario entailed the investigation of the occurrence or lack thereof, of injection-induced fault reactivation at this predetermined injection rate of 722 Scf/day. Simulations reflecting the characteristics of fault reactivation were conducted, and are indicative of relations between fault opening stress, reactivation time, hydraulic fracture permeability, fracture propagation length, and leakage. Conclusively, the viability of the combination of CO2-EOR and sequestration were seen to depend on the technicalities of fault reactivation. In some cases, reactivation resulted in increases of accessible storage capacity, whereas, in other instances, it led to the leakage of the injected CO2.
Highlights
In the recent past, Trinidad and Tobago has ranked as one of the world’s leaders for carbon dioxide emissions per capita
The country is showing intentions of transitioning to a more environmentally conscious society. In keeping with this outlook, the country deposited its instrument of ratification to the Paris Agreement on climate change on February 22, 2018, which detailed the country’s commitment to reducing cumulative greenhouse gas emissions by 15%, by the year 2030
The goal of this research is to (1) determine the optimum injection pressure for the combined process of C O2-EOR and geologic carbon sequestration within a mature oil reservoir, (2) quantify the leakage of CO2, and/or, the constituent volumes of C O2 associated with each type of trapping within the injected formation, (3) capture the characteristics of fault reactivation and yield using simulation models constructed in the GEM suite of the commercial reservoir simulator CMG, (4) compare these various faulted reservoir models to observe the effects of fault reactivation and C O2 migration on storage capacity, (5) simulate variations in fracture permeability of the fault to characterize the effects on reactivation time and leakage
Summary
Trinidad and Tobago has ranked as one of the world’s leaders for carbon dioxide emissions per capita. The country is showing intentions of transitioning to a more environmentally conscious society In keeping with this outlook, the country deposited its instrument of ratification to the Paris Agreement on climate change on February 22, 2018, which detailed the country’s commitment to reducing cumulative greenhouse gas emissions by 15%, by the year 2030. Notwithstanding this intended commitment, if the need arises for safer, more efficient methods of carbon dioxide removal in the future, preferences should be readily available. Emphasizes the applicability of geologic carbon sequestration as a substantive emission mitigation approach for the country and forms part of the motivation behind this study
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