Practical EOR Agents - There is more to EOR than CO2

Dean, E. W.; French, Josh; Pitts, Malcolm; Wyatt, Kon

doi:10.2118/190424-ms

Cited by 8 publications

(6 citation statements)

References 3 publications

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“…The associated goals of reducing greenhouse gas emissions and increasing oil recoveries have led to growing interest in injecting CO 2 and/or produced rich gas hydrocarbons for both gas storage and enhanced oil recovery (EOR). ,,− This interest has resulted in several recent pilot-scale injections of CO 2 and rich gas hydrocarbons into the Bakken, ,,, but experimental data needed to support successful field projects that compare these gases’ abilities to mobilize crude oil under relevant reservoir conditions are limited. Recently, CO 2 and various hydrocarbon gas minimum miscibility pressures (MMPs) were measured with crude oils produced from the Three Forks (TFs) and Middle Bakken (MB) intervals of the Bakken Petroleum System.…”

Section: Introductionmentioning

confidence: 99%

Comparison of CO₂ and Produced Gas Hydrocarbons to Recover Crude Oil from Williston Basin Shale and Mudrock Cores at 10.3, 17.2, and 34.5 MPa and 110 °C

et al. 2021

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Carbon dioxide and hydrocarbon gases including methane, ethane, propane, and produced gas (69.5/21/9.5 mol ratio of methane/ethane/propane) were used to recover oil from rock samples collected in the Middle Bakken (MB) target drilling zone and from a Lower Bakken Shale (LBS) source rock. Experiments were designed to mimic the fracture-dominated flow expected to occur during gas injection into hydraulically fractured unconventional reservoirs such as the Bakken Petroleum System. Higher pressures recovered oil (and heavier hydrocarbons) more efficiently than lower pressures from both rock samples for each of the test gases but recoveries varied dramatically with the gas used. In general, oil recovery efficiencies from both MB and LBS rocks were the highest with propane, followed by ethane, CO2, and produced gas, and finally methane. Propane and ethane were the most efficient in recovering oil hydrocarbons from the rock samples at all three pressures, although ethane required higher pressures. Recoveries with CO2 and produced gas were low at 10.3 MPa but increased substantially at higher pressures with the recoveries achieved at 34.5 MPa approximating those achieved at lower pressures using propane and ethane. Finally, methane was only capable of significant oil recoveries from MB samples at the highest (34.5 MPa) test pressure but was not effective in mobilizing hydrocarbons from the tighter LBS samples at any of the pressures tested. Molar densities and the related injected gas solvent strengths at the three test pressures had a strong influence on oil recovery rates. For example, when molar densities of all five gases at the three test pressures were correlated with total hydrocarbon recoveries, linear correlation coefficients (r 2) were significant (0.69 for 1 h oil recoveries from the MB mudrock samples and 0.68 for the 24 h oil recoveries from the LBS shale samples). When oil recoveries at the three test pressures were compared to the molar densities of each individual gas, linear correlation coefficients (r 2) ranged from 0.89 to 0.99 for the recoveries from the MB samples, and 0.95 to >0.99 for the LBS samples for all of the gases except propane (which gave high recoveries at every test pressure, consistent with the fact that propane’s molar density shows little change at the three test pressures). The results of these laboratory studies indicate that ethane, propane, or very rich produced gas should be capable of recovering oil from unconventional reservoirs at significantly lower pressures than leaner produced gas or CO2, although both produced gas and CO2 could be effective at higher pressures.

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Section: Introductionmentioning

confidence: 99%

Comparison of CO₂ and Produced Gas Hydrocarbons to Recover Crude Oil from Williston Basin Shale and Mudrock Cores at 10.3, 17.2, and 34.5 MPa and 110 °C

et al. 2021

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“…The desire to reduce greenhouse gas emissions and increase oil production has led to rapidly increasing interest in reinjecting CO 2 and/or rich gas for enhanced oil recovery (EOR). ,,− Currently, a major pilot program is being conducted to capture CO 2 from lignite-fired power plants in western North Dakota to inject for carbon storage (and potentially for future EOR projects) in the nearby Bakken and other formations within the basin . These increasing interests have led to several recent pilot-scale injections of natural gas and CO 2 into the Bakken. ,,− …”

Section: Introductionmentioning

confidence: 99%

Comparison of CO₂ and Produced Gas Hydrocarbons to Dissolve and Mobilize Bakken Crude Oil at 10.3, 20.7, and 34.5 MPa and 110 °C

Hawthorne

Miller

2020

Energy Fuels

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The ability of an injected gas to dissolve crude oil hydrocarbons may be a major factor controlling the success of enhanced oil recovery (EOR) projects in unconventional reservoirs. Multiple laboratory gas injection tests were conducted using Bakken crude oil in which the gas-dominated upper phase in equilibrium with the bulk crude oil was collected and analyzed to determine dissolved crude oil concentrations and their molecular weight distributions. Dissolved concentrations varied greatly among the test gases, as well as at different pressures for all of the fluids except propane. The ranges of total dissolved hydrocarbons at 10.3, 20.7, and 34.5 MPa were methane (8–67 mg/mL), ethane (40–228 mg/mL), propane (230–278 mg/mL), and CO2 (13–254 mg/mL). The oil solubility in a representative produced gas (69.5/21/9.5 methane/ethane/propane) ranged from 9 to 145 mg/mL. The gases and pressures that mobilized the lowest total hydrocarbon concentrations were also the least effective at mobilizing heavier hydrocarbons. For example, the C20–C36 fraction of the crude oil that was mobilized with each gas exposure at 10.3–34.5 MPa was methane (<1–6%), ethane (12–95%), propane (58–99%), produced gas (<1–33%), and CO2 (<1–40%), indicating concentration of the heavier hydrocarbons in the residual crude oil after exposure to gases (and pressures) that are less effective. Residual crude oil viscosities after gas exposure showed significant increases (with the notable exception of propane at all three pressures), also consistent with each test gas’s ability to dissolve heavier hydrocarbons. Consideration of each gas’s density changes with pressure correlated well with their abilities to dissolve crude oil, and increases in pressure always increased oil solubilities regardless of each gas’s minimum miscibility pressure (MMP) value with the crude oil used for these mobilization experiments. Multiple exposures of a crude oil sample to fresh test gas showed declining dissolved hydrocarbon concentrations demonstrating that crude oil solubilities were not controlled by saturation solubility, but were controlled by equilibrium partitioning of hydrocarbons between the gas-dominated and oil-dominated phases.

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“…The recent dramatic increase in gas production has depressed natural gas prices as well as produced excess low-value ethane and, in some locations, even excess natural gas liquids (NGLs) like propane and butanes. , Excess rich gas is especially problematic to operators located in areas where gas processing and pipeline infrastructure is inadequate to handle the quantities of gas produced, thus forcing operators to reduce oil production and/or increase gas flaring. , Inadequate infrastructure problems are especially prevalent in the North Dakota (USA) Bakken field, where 20% of the produced gas was flared during the first 10 months of 2019, resulting in more than 40 000 t per day of CO 2 -equivalent emissions . In addition to CO 2 , operators are interested in produced gas injections in an effort to reduce flaring and increase oil recovery and/or store natural gas, and since 2014, three pilot-scale injections of produced gas or NGLs have been performed in the Bakken field. ,− …”

Section: Introductionmentioning

confidence: 99%

Experimental Determinations of Minimum Miscibility Pressures Using Hydrocarbon Gases and CO₂ for Crude Oils from the Bakken and Cut Bank Oil Reservoirs

et al. 2020

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Minimum miscibility pressures (MMPs) were measured at reservoir temperatures using a capillary-rise vanishing interfacial tension (VIT) technique for four crude oils collected from different formations in the deep/hot Bakken Petroleum System and the shallow/cool Cut Bank field. Potential injection fluids tested were pure CO2, methane, ethane, propane, and hydrocarbon gas mixtures typical of the rich gas produced from tight shale formations like the Bakken Petroleum System (ca. 7/2/1 mol ratios of methane/ethane/propane). Depending on the oil and test temperature, MMPs were achieved with the fluids in the gas, liquid, or supercritical states. Regardless of the physical state of the test fluids at MMP, propane achieved MMP at the lowest pressure with all four crude oils, followed by ethane, then CO2 and produced gas, and finally methane requiring the highest pressures. For the Bakken (110 °C) and Three Forks crudes (127 °C), MMPs dropped from 29 to 31 MPa with methane from 16.2 to 18.7 MPa with CO2 or produced gas, and further lowered from 9.2 to 10 MPa with ethane, and from 3.8 to 4.3 MPa with propane. Changes in the MMPs with the different fluids were even more dramatic for the Madison and Cut Bank crude oils (both at 28 °C) with methane MMPs about 28–29 MPa, produced gas at 10–10.6 MPa, CO2 at 8.3–8.7 MPa, ethane at 4.2–4.5 MPa, and propane only requiring 1.3–1.4 MPa to achieve MMP. Enriching produced gas by adding either ethane or propane showed approximately linear decreases in the MMPs with the Bakken crude oil. For example, increasing propane in produced gas from 6.7 to 25 mol % reduced the Bakken crude oil’s MMP from 18 to 12.7 MPa, while increasing ethane from 13.5 to 68 mol % reduced the MMP from 18.6 to 11.4 MPa. The results of this experimental study show that injecting produced rich gas may be as effective as injecting CO2 for enhancing oil recovery and that enriching produced gas with ethane or propane may be superior to CO2 for EOR in both shallow/cool and deep/hot reservoirs.

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Practical EOR Agents - There is more to EOR than CO2

Cited by 8 publications

References 3 publications

Comparison of CO₂ and Produced Gas Hydrocarbons to Recover Crude Oil from Williston Basin Shale and Mudrock Cores at 10.3, 17.2, and 34.5 MPa and 110 °C

Comparison of CO₂ and Produced Gas Hydrocarbons to Recover Crude Oil from Williston Basin Shale and Mudrock Cores at 10.3, 17.2, and 34.5 MPa and 110 °C

Comparison of CO₂ and Produced Gas Hydrocarbons to Dissolve and Mobilize Bakken Crude Oil at 10.3, 20.7, and 34.5 MPa and 110 °C

Experimental Determinations of Minimum Miscibility Pressures Using Hydrocarbon Gases and CO₂ for Crude Oils from the Bakken and Cut Bank Oil Reservoirs

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Practical EOR Agents - There is more to EOR than CO2

Cited by 8 publications

References 3 publications

Comparison of CO2 and Produced Gas Hydrocarbons to Recover Crude Oil from Williston Basin Shale and Mudrock Cores at 10.3, 17.2, and 34.5 MPa and 110 °C

Comparison of CO2 and Produced Gas Hydrocarbons to Recover Crude Oil from Williston Basin Shale and Mudrock Cores at 10.3, 17.2, and 34.5 MPa and 110 °C

Comparison of CO2 and Produced Gas Hydrocarbons to Dissolve and Mobilize Bakken Crude Oil at 10.3, 20.7, and 34.5 MPa and 110 °C

Experimental Determinations of Minimum Miscibility Pressures Using Hydrocarbon Gases and CO2 for Crude Oils from the Bakken and Cut Bank Oil Reservoirs

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Product

Resources

About

Comparison of CO₂ and Produced Gas Hydrocarbons to Recover Crude Oil from Williston Basin Shale and Mudrock Cores at 10.3, 17.2, and 34.5 MPa and 110 °C

Comparison of CO₂ and Produced Gas Hydrocarbons to Recover Crude Oil from Williston Basin Shale and Mudrock Cores at 10.3, 17.2, and 34.5 MPa and 110 °C

Comparison of CO₂ and Produced Gas Hydrocarbons to Dissolve and Mobilize Bakken Crude Oil at 10.3, 20.7, and 34.5 MPa and 110 °C

Experimental Determinations of Minimum Miscibility Pressures Using Hydrocarbon Gases and CO₂ for Crude Oils from the Bakken and Cut Bank Oil Reservoirs