Deposition of "Asphaltenes" during CO2 Injection and Implications for EOS Description and Reservoir Performance.

Broad, J.; Majid, M.N. Ab; Ariffin, Tajnor Suriya Taju; Hussain, A.A.A.; Basher, A.B.

doi:10.2523/iptc-11563-ms

Cited by 3 publications

(1 citation statement)

References 6 publications

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“…The derived correlation also showed a good agreement for these larger n-alkanes. The correlation was compared with those of Moysan et al (1986) and Carroll and Mather (1995). As shown in Fig.…”

Section: Appendix A-citation Results Of Asphaltene-flow-assurance Resmentioning

confidence: 99%

Managing Experimental-Data Shortfalls for Fair Screening at Concept Selection: Case Study To Estimate How Acid-Gas Injection Affects Asphaltene-Precipitation Behavior

Yonebayashi

Takabayashi

Iizuka

et al. 2016

Oil and Gas Facilities

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Development Company have complexity of technical evaluation. Such complexity might be encountered when assuming an emerging condition or when introducing emerging technologies. In such cases, potential concepts are often difficult to evaluate fairly with existing technologies, but can possibly be evaluated with newly introduced or developing evaluation measures. However, these new and developing measures require cost that can be justified at the matured stage of development, but that cannot be justified at the concept-screening stage. In the future, the exploration and production (E&P) industry will be required to access more emerging fields of lesser easy oil; thus, this case study will be an example engaging a similar situation. Potential Development Concepts. Gas reinjection is the main scenario used in this study to manage produced sour gas. Many gasreinjection projects have been implemented throughout the world, and available research on the topic was referenced to support this study (Darmentaev et al. 2010; Hopper et al. 2008). The general process involves reinjecting the associated acid gas back into the reservoir. The purpose of gas reinjection is to maintain the reservoir pressure as much as possible, preferably at greater than the minimum miscibility pressure (MMP) for an extended amount of time. This can improve the oil-displacement efficiency. In addition, pressure maintenance at greater than the bubblepoint pressure can prevent premature gas breakthrough into the production wells. This not only increases the ultimate oil recovery, but also reduces the gas-processing volume, which is the key driver for reducing the amount of nonhydrocarbon byproducts (e.g., sulfur and CO 2). For technical justification of gasflooding EOR compared with other options, supplemental discussion was added as follows. Other EOR

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Section: Appendix A-citation Results Of Asphaltene-flow-assurance Resmentioning

confidence: 99%

Managing Experimental-Data Shortfalls for Fair Screening at Concept Selection: Case Study To Estimate How Acid-Gas Injection Affects Asphaltene-Precipitation Behavior

Yonebayashi

Takabayashi

Iizuka

et al. 2016

Oil and Gas Facilities

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Re-equilibrium of Asphaltenes by Repressurizing after Precipitation in Natural Depletion and CO₂ Enhanced Oil Recovery Schemes

2018

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In a series of isothermal depressurizing tests to measure asphaltene onset pressure (AOP), several depressurizing operations are usually conducted to multiple AOPs using the same lot of fluid subsamples. After one depressurizing operation is finished, the pressure/temperature condition is reset to the initial condition. Then, the next depressurizing run is performed. Before the next run, the fluid sample must equilibrate again by dissolving precipitated asphaltenes from the previous step. According to our many experiences with isothermal depressurizing tests for measuring AOPs, we know that redissolving asphaltenes depends highly upon the characteristics of a fluid sample. Some fluids redissolve asphaltenes quickly, while other samples need a lot of time. This study focused on fluid-dependent asphaltene re-equilibrium during a series of isothermal depressurizing tests. To investigate asphaltene re-equilibrium, the authors re-examined past experimental data for two types of crude oils. In the experiment, continuous power of light transmittance (PLT) was monitored for all stages in the series of AOP measurements. Two series of isothermal depressurizing tests were separately performed to evaluate CO 2 -induced asphaltene risks for two fluid samples. Three or four total steps of depressurizing were conducted in order of CO 2 addition ratios: 0, 20, 40, and 60 mol %. After a depressurizing process finished, pressure was increased above AOP to dissolve precipitated asphaltenes. PLT profiles in equilibrium steps between each depressurizing step were compared from a viewpoint of equilibrium time and/or PLT profile fluctuation. One of the fluids showed quick re-equilibrium of asphaltenes and smooth PLT profiles, whereas the other took much longer to achieve equilibrium and had fluctuating PLT profiles. This information suggested that easyequilibrium-achievable fluids would be a preferred target for CO 2 enhanced oil recovery because of its potential use of pressure control for mitigating asphaltenes. In the case of easy-equilibrium-achievable fluid, when a production problem is caused by asphaltene precipitation, repressurization by temporary shut-in and/or production rate control can be an effective mitigation.Article pubs.acs.org/EF

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High Pressure Gas EOR PVT Experimental Programs: Challenges in Measurements and Data Interpretations

Alboudwarej

Sheffield

Srivastava

et al. 2018

Day 4 Tue, April 17, 2018

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Standard gas Enhanced Oil Recovery (EOR) Pressure-Volume-Temperature (PVT) program includes experiments such as solubility/swelling, multi-contact, slim tube, vapor-liquid equilibria (VLE) tests, and fluid property measurements. These tests are designed to determine the extent of gas miscibility and mixture phase behavior during gas injection in hydrocarbon reservoirs. These experimental programs are known to be expensive and time consuming. The degree of complexity increases as the industry move into conducting gas EOR PVT for high/ultra-high-pressure reservoirs. The focus of this paper is to demonstrate the challenges associated with these measurements and evaluate the merit, applicability, and usage of such data for fluid model development for high pressure gas EOR studies. Associated challenges include utilizing gas concentrations up to 90% mole during swelling tests to determine critical mixture composition. Determination of dew point pressures by visual inspection or liquid build-up method proved inefficient. An interpretation of pressure-volume data showed good promise for determining both saturation pressure and liquid build-up curve for opaque dew point systems. VLE tests were designed at gas concentrations close to critical mixture composition to generate phases with increased affinity for mass transfer. Measured Minimum Miscibility Pressure (MMP) for all studied oil and gas systems were less than 6000 psia, except for N2 gas. Such relatively low MMP values suggest that development of full miscibility is not a concern for these high-pressure fluid systems. Such relatively low MMP values suggest that generated miscibility is not a concern for these high-pressure fluid systems. Instead the focus shifted to determine and effectively model the first contact miscibility pressures for these fluid systems (if it existed at pressures less than initial reservoir pressure). Measured MMPs were assigned a low weight factor in EoS model optimization process. Swelling test data for gas concentrations lower than 50% mole was of little value for EoS model optimization. Presence of precipitated asphaltenes challenged accurate measurement of liquid phase density and viscosity, as capture and analysis of a representative sample was very difficult. A knowledge of asphaltenes phase envelope for mixtures of reservoir fluid and injection gas proved to be invaluable. A robust gas EOR PVT database was generated for mixtures of 6 injection gases and 7 deep water Gulf of Mexico Wilcox Trend reservoir fluids. Tests were carried out at pressures as high as 20000 psia and temperatures ranging between 230-265 °F. New high-pressure testing capabilities were developed, and modified data interpretation techniques were implemented. Lessons learned during the measurement, interpretation and application of these high-pressure gas EOR PVT data helped us design an effective measurement program. The developed fit-for-purpose experimental program leads to reduced cost (elimination of unnecessary tests) and increased reliability of high pressure phase equilibria and fluid property data for gas EOR reservoir simulation studies.

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Deposition of "Asphaltenes" during CO2 Injection and Implications for EOS Description and Reservoir Performance.

Cited by 3 publications

References 6 publications

Managing Experimental-Data Shortfalls for Fair Screening at Concept Selection: Case Study To Estimate How Acid-Gas Injection Affects Asphaltene-Precipitation Behavior

Managing Experimental-Data Shortfalls for Fair Screening at Concept Selection: Case Study To Estimate How Acid-Gas Injection Affects Asphaltene-Precipitation Behavior

Re-equilibrium of Asphaltenes by Repressurizing after Precipitation in Natural Depletion and CO₂ Enhanced Oil Recovery Schemes

High Pressure Gas EOR PVT Experimental Programs: Challenges in Measurements and Data Interpretations

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Deposition of "Asphaltenes" during CO2 Injection and Implications for EOS Description and Reservoir Performance.

Cited by 3 publications

References 6 publications

Managing Experimental-Data Shortfalls for Fair Screening at Concept Selection: Case Study To Estimate How Acid-Gas Injection Affects Asphaltene-Precipitation Behavior

Managing Experimental-Data Shortfalls for Fair Screening at Concept Selection: Case Study To Estimate How Acid-Gas Injection Affects Asphaltene-Precipitation Behavior

Re-equilibrium of Asphaltenes by Repressurizing after Precipitation in Natural Depletion and CO2 Enhanced Oil Recovery Schemes

High Pressure Gas EOR PVT Experimental Programs: Challenges in Measurements and Data Interpretations

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Re-equilibrium of Asphaltenes by Repressurizing after Precipitation in Natural Depletion and CO₂ Enhanced Oil Recovery Schemes