The project goal is to determine the feasibility of reinjecting captured rich gas into a Bakken reservoir to enhance oil recovery. Specific research objectives related to this goal are as follows:
Energy & Environmental Research Center (EERC) – University of North Dakota, Grand Forks, ND 58202-9018
North Dakota is well-situated to demonstrate the implementation of rich gas-based EOR for tight oil formations. Although flaring associated with Bakken oil production has been reduced significantly in recent years, as of March 2019, approximately 19 percent of the rich gas produced in association with Bakken oil production continues to be flared. The associated gas from Bakken oil production operations is typically a mixture dominated by methane with a significant amount of ethane and other hydrocarbons. The results of recent preliminary laboratory investigations at the EERC suggest that pure ethane and mixtures of methane and ethane may be used to mobilize oil from Bakken rocks and thus could be viable injection fluids for EOR operations. The EERC is working with Liberty Resources (LR) to design and conduct an EOR pilot test using rich gas. The project is a joint initiative between the EERC, North Dakota Industrial Commission (NDIC) through the Bakken Production Optimization Program (BPOP), LR, and the U.S. Department of Energy (DOE). Project activities will be coordinated, managed, and evaluated by the EERC. LR will be responsible for providing the wells and rich gas necessary for the test and will operate the injection, production, and monitoring activities. An improved understanding of wettability, relative permeability, and fracture network distribution across the Bakken will be developed using advanced reservoir characterization techniques. Alternative injection strategies to optimize EOR strategies at scales larger than a DSU will be investigated using advanced reservoir-modeling methods. ML and BDA will be used to streamline pilot performance assessments.
Estimates for original oil in place (OOIP) in the Bakken petroleum system range from 300 billion to 900 billion barrels. Current resource recovery factors for Bakken wells are typically 10% or less. If this trend continues, billions of barrels of oil will be left stranded in the reservoir. Analysis conducted by the North Dakota Pipeline Authority indicates that the current gas-gathering infrastructure in North Dakota (including pipelines, compressor stations, and gas processing facilities) is insufficient to accommodate all of the associated gas that is produced as part of oil production from the Bakken. The geographically isolated location of the Bakken oil play relative to large natural gas markets, combined with continued low natural gas prices, has made it economically challenging for industry to invest capital in expanding gas-gathering infrastructure in North Dakota. Therefore, management of rich gas production from the Bakken is still a high priority for government and industry stakeholders in North Dakota. This project will demonstrate the viability of utilizing rich gas for EOR in the Bakken, which will result in reduced flaring and an improvement in recovery factors. The primary impacts of this project will be reductions in greenhouse gas emissions associated with Bakken activities, and potentially the production of billions of barrels of incremental oil.
The project was initiated on September 1, 2017. A hearing of the NDIC Oil and Gas Division was held September 21, 2017, for the purpose of LR providing testimony for its application to obtain the necessary permits for the pilot injection test. Permits for injection activities in six wells have been granted to LR. LR has purchased a compression unit that is necessary for the operation of the pilot injection test. Specific accomplishments include the following:
The pilot test by LR and activities surrounding the pilot test are complete. IFT and contact angle measurements of fluid–fluid and fluid–rock pairs are ongoing. MICP analyses are in progress. ML approaches are being explored for geomechanical properties estimation using XRD, XRF, and geomechanical results from core and cutting samples. Systematic simulation runs are being conducted to optimize the operational parameters in the huff ‘n’ puff process when a representative Bakken rich gas composition is used. Two simulation models are being developed to investigate multiple-well huff ‘n’ puff EOR operations in the Bakken. Hydraulic and natural fractures are considered in these models to capture the fluid flow behavior in the complex fractured reservoir. Advanced EOR strategies including high-pressure propane injection and surfactant injection are being studied based on the latest field data. Set 2 data will be analyzed using response surface methodology, regression, and/or ML techniques to quantify the effect of the operational factors on DSU production. The virtual learnings from Set 1 and Set 2 will provide the basis for optimization studies looking to maximize oil production and minimize water production or, equivalently, to maximize the net present value of the DSU. One or more of the simulations that generated data at monthly resolution will be rerun at higher time-series resolution (e.g., hourly) to explore real-time