Modeling Study of the Unconventional Bakken Formation for Gas Injection EOR

Jin, Lu; Jiang, Todd; Dotzenrod, Neil W.; Patil, Shirish; Klenner, Robert; Sorensen, James A.; Bosshart, Nick

doi:10.3997/2214-4609.201902262

Cited by 2 publications

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“…NNCs in the EDFM are treated as regular connections in traditional simulators and the NNC transmissibility factors are linked with permeabilities in the grid blocks. 26 This improvement made the incorporation of hundreds of fractures in a single model much less challenging compared to other fractured reservoir simulation methods. Therefore, the EDFM method was selected to simulate the MWMF scenarios in this study.…”

Section: Simulation Investigationmentioning

confidence: 99%

“…The EDFM algorithm overcomes these challenges by employing non-neighboring connections (NNCs) for an effective and flexible simulation of matrix-fracture and fracture–fracture fluid flow. NNCs in the EDFM are treated as regular connections in traditional simulators and the NNC transmissibility factors are linked with permeabilities in the grid blocks . This improvement made the incorporation of hundreds of fractures in a single model much less challenging compared to other fractured reservoir simulation methods.…”

Section: Laboratory and Simulation Investigationsmentioning

confidence: 99%

“…Gas injection EOR technologies including miscible and immiscible flooding using CO 2 and rich gas have been widely employed to improve oil recovery in conventional reservoirs with great success. – To reproduce this success in unconventional reservoirs, an increasing volume of work, including laboratory experiments, geologic modeling, and reservoir simulation, has been performed to investigate the feasibility of using produced gas, CO 2 , and other EOR injectates for improving oil production in these tight and/or shale formations. – A variety of laboratory experiments were designed to investigate the fundamental flow and EOR mechanisms in unconventional rocks. – Huff “n” puff and high-pressure gas extraction were the most frequently reported experiments for gas EOR investigation in the laboratory. − Milad et al systematically reviewed the HnP experiments performed for various shale/tight reservoirs. The experiments attempted to evaluate possible EOR mechanisms including repressurization, injection-induced fracturing, diffusion of gas into matrix pores, gas–oil interfacial tension (IFT) reduction, oil swelling, oil viscosity reduction, wettability alteration toward increasing water wetness, vaporization of lighter oil components, relative permeability hysteresis, and solution gas drive to attain miscible gas EOR in unconventional liquid reservoirs .…”

Section: Introductionmentioning

confidence: 99%

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Investigating Enhanced Oil Recovery in Unconventional Reservoirs Based on Field Case Review, Laboratory, and Simulation Studies

et al. 2022

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Aimed at advancing gas injection enhanced oil recovery (EOR) technologies in unconventional reservoirs, this study comprised a series of activities to bridge the gap between the theoretical study and actual field applications. Twenty-four EOR pilot tests were collected from the major unconventional plays in North America to evaluate the performance of different EOR technologies. Fit-for-purpose experiments and simulations were performed to investigate the effects of injection rate and pressure on EOR performance, as well as to reveal the effectiveness of huff "n" puff (HnP) cycles in actual field operations. The selection of injection rate and pressure as key parameters for investigation was based on field observations and communications with oil and gas operators because these two parameters play critical roles in both facility design and overall cost for an EOR project. Results showed that miscible EOR with a high gas injection rate and pressure is required for field operations because the injected gas needs to penetrate and extract oil from the tight matrix. Experimental results indicated that there is a correlation between oil recovery and the logarithm of core volume for miscible EOR. Immiscible gas EOR could not yield a satisfactory EOR response in actual reservoirs because the injected gas tends to flow through fractures instead of penetrating the matrix to interact with oil. Results also showed that reaching minimum miscibility pressure (MMP) does not guarantee an optimum EOR operation in unconventional reservoirs. Pressure higher than MMP is preferred in field operations. When designed properly, up to a tenfold oil production rate boost is achievable in field applications within a short period. However, such a high-performance operation is only effective in the first several HnP cycles due to the limited gas penetration depth into the rock matrix.

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Section: Simulation Investigationmentioning

confidence: 99%

Section: Laboratory and Simulation Investigationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Investigating Enhanced Oil Recovery in Unconventional Reservoirs Based on Field Case Review, Laboratory, and Simulation Studies

et al. 2022

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Report on the First Rich Gas EOR Cyclic Multiwell Huff N Puff Pilot in the Bakken Tight Oil Play

Pospisil¹,

Weddle²,

Strickland³

et al. 2020

SPE Annual Technical Conference and Exhibition

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Objectives/Scope This field case history details the objectives, design, field operations, and production, pressure, and other surveillance results of the first rich gas multiwell cyclic huff ‘n’ puff pilot in the Bakken and Three Forks intervals of the Williston Basin. The broad goal of the enhanced oil recovery (EOR) pilot was to identify key performance metrics of rich gas injection leading to the design of a commercial field-scale EOR process. Objectives included demonstrating the ability to contain gas within the target intervals vertically and laterally and build pressure to promote a miscible displacement process in a fully developed 1280-acre drill spacing unit (DSU) in the Bakken tight oil play. Methods, Procedures, Process The paper includes the geologic reservoir description of the pilot area in the northeast Williams County Nesson Anticline area based on well logs, seismic, and core materials. Background includes the development history of the eleven-well, 1280-acre DSU including well completions and production data. The paper describes details on methods and results of laboratory studies of representative Bakken fluids and core materials including characterizing PVT (pressure, volume, temperature) properties, minimum miscibility pressure (MMP) measurements, and fluid extraction tests. Case results include a description of the facilities and field operations through the execution of the pilot. Further, the paper includes key considerations in the planning and design phase, including injection order, offset monitoring, and facilities design considerations for gas rates and volumes. Production results from within the DSU and surrounding DSUs include a total of 24 horizontal Bakken or Three Forks wells. Surveillance results include oil, water, and gas rates; injection and downhole pressures; and gas chromatograph data from injection and offset wells as a basis for assessing pilot results versus goals and objectives. Results, Observations, Conclusions Bakken/Three Forks produced gas is miscible with reservoir fluids at pressures above ~2500 psi, given the relatively high fluid fraction of ethane and propane. This produced gas recovers a large fraction of reservoir fluids from Middle Bakken, Three Forks, and Upper and Lower Bakken Shales in laboratory extraction tests. Gas injection into the Bakken and Three Forks intervals was achieved through the full range of the pilot design, and over 90% of the injection gas was recovered as wells were returned to production based on measured rates, volumes, and other surveillance data. While actual pilot gas injection rates were too low to achieve a material EOR oil response, surveillance data indicated that pressures increased with gas injection and that gas was contained within the 1280-acre DSU as designed. Further, history-matched simulations indicated that higher gas injection rates could yield EOR recoveries comparable to that reported in successful Eagle Ford projects. Key insights include that much higher gas injection rates are required for an economical process and that initiation of gas injection cycles earlier in the well life will reduce the volume of gas and injection time required to build bottomhole pressures above the MMP to promote EOR. Novel/Additive Information This first multiwell rich gas injection pilot in the Bakken/Three Forks play identified several design and operational efficiencies beneficial to an economical field-scale project. For example, jet pump installations allowed gas injection operations without modifying production wells via costly workovers. Injection/production conversions could be completed at minimal cost by cycling out jet pumps and installing pressure gauges. Further, wells completed with cemented plug and perforated liners for hydraulic fracture stimulation may promote improved gas injection conformance across the horizontal completed intervals.

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Modeling Study of the Unconventional Bakken Formation for Gas Injection EOR

Cited by 2 publications

References 0 publications

Investigating Enhanced Oil Recovery in Unconventional Reservoirs Based on Field Case Review, Laboratory, and Simulation Studies

Investigating Enhanced Oil Recovery in Unconventional Reservoirs Based on Field Case Review, Laboratory, and Simulation Studies

Report on the First Rich Gas EOR Cyclic Multiwell Huff N Puff Pilot in the Bakken Tight Oil Play

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