The overall objective of this project is to increase recovery and sustain production from existing Bakken wells by implementing a novel Enhanced Oil Recovery (EOR) technology that has the potential to resolve some of the pivotal issues associated with gas containment in this field. More specifically, this project seeks to optimize the performance of foam-assisted hydrocarbon gas injection in the Middle Bakken/Three Forks by improving the current scientific understanding of the fundamental mechanisms involved in this process and demonstrating its potential through a field pilot test. An integrated and collaborative framework is proposed to implement these objectives in three different stages: Stage I. Characterization and Chemical Screening/Optimization, to perform laboratory evaluation of foam-based conformance control for injected hydrocarbon gases and customize selected chemicals, as needed, for application under Bakken conditions; Stage II. Multi-scale Core Flooding and Numerical Simulation, to understand the fundamental mechanisms involved in Foam-Assisted Gas Injection (FAGI) EOR using selected formulations and Bakken rock/fluid samples at reservoir conditions and develop/calibrate multi-scale flow models and simulators to predict field performance; and Stage III. Field Pilot Testing Program, to implement this technology in the field through a well-designed pilot test in the Bakken.
University of Wyoming, Laramie, WY 82071
The proliferation of hydraulic fracturing and the low primary recovery rates attainable from unconventional plays provide a strong value case for EOR processes. The large surface area created by fracture networks allows injected fluids to come in contact with the matrix and increase hydrocarbon recovery in formations where more than 90% of the resource is left behind. Miscible gas injection, through continuous flooding or cyclic gas injection (huff and puff), has received a surge of interest in recent years; however, issues associated with gas containment and conformance control were reported in highly heterogeneous formations, such as the Bakken. A recent field application by Dow Chemical in a South Texas shale play overcame some of these issues and yielded significant incremental oil production above those of primary depletion and tertiary gas injection processes. Conformance control could be achieved by injection of hydrocarbon gas and aqueous surfactant solutions to generate stable foam within the fractures. By trapping pockets of gas in brine, gas mobility can be significantly reduced, leading to a substantial rise in pressure gradients across proppant-filled fractures. This establishes the entry pressure needed for gas-to-oil displacements from fracture walls into the matrix. This could become particularly successful when imbibition of surfactant solution into the matrix is suppressed. Foam can potentially enhance the macro-scale sweep efficiency by mitigating the effects of heterogeneity, gas segregation, and viscous instability associated with gas injection.
The outcome of the proposed project will allow operators to maximize the producible oil by using the previously fractured reservoir volumes and existing hydraulically fractured wells while minimizing the number of wells to be drilled, which in turn will lead to informed decisions on their capital investment, development plan, resource evaluation, and reserve replacement. Successful completion of the proposed project will deliver a methodology that allows the development of an EOR method that will be a “game changer” for EOR processes in heterogeneous unconventional oil plays, such as the Bakken.
Once proven successful in the field both technically and economically, this technology may be expanded to augment the play development. This project will greatly benefit the oil and gas industry overall as it will help boost the growth in U.S. onshore oil production and provide greater long-term energy security at lower costs.
In late November, the North Dakota Industrial Commission gave approval to Hess to move forward with the plan to implement foam-assisted gas injection at the project site near Ross in Mountrail County, North Dakota. The EN-Ortloff pilot site, owned by Hess, currently has eight horizontal wells completed in the Bakken and Three Forks formations.
Hess has contacted vendors and received bids for the rental of main and gas lift compressors required for the injection of gas and chemicals at the project site.
Over the past two months, the Dow team has been actively working to ascertain and characterize phase stable surfactant solutions (5000 parts per million (ppm)) at T = 115°C and total dissolved solids (TDS) = 25% (synthetically produced brine). They have successfully identified several surfactant candidates that remain phase stable (clear solutions) for 48 hours. Formulation research and development (R&D) efforts are ongoing using selected surfactant candidates to obtain low-temperature stable field trial product offerings.
Budget Period 1 – Performer Contribution: $535,695
Budget Period 2 – Performer Contribution: $640,213
Budget Period 4 – Performer Contribution: $363,797
Planned Total Funding – Performer Contribution: $2,003,287