CO2-EOR mechanisms in huff-n-puff operations in shale oil reservoirs based on history matching results

Alfarge, Dheiaa; Wei, Mingzhen; Bai, Baojun

doi:10.1016/j.fuel.2018.04.012

Cited by 85 publications

(37 citation statements)

References 4 publications

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“…The properties data of oil components have been listed in Table . The other physiochemical properties of tight oil could be found in references …”

Section: Microscopic Physical Mechanisms Of Nitrogen Gasmentioning

confidence: 99%

“…In contrast to conventional reservoirs, the tight oil reservoirs are rich in nano‐millimeters pores which lead to ultra‐low permeability and very low primary recovery (less than 15%) . The tiny pore throats with confinement effect prevent fluid flow from reservoir matrix to natural/hydraulical fractures; as a result, the tight oil production rate would sharply decline . Thus, improving tight oil production has become an urgent issue for the development of tight oil resources.…”

Section: Introductionmentioning

confidence: 99%

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Investigation of CO₂/N₂ injection in tight oil reservoirs with confinement effect

Wang

et al. 2019

Energy Science & Engineering

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This paper investigates the CO2/N2 injection process in tight oil reservoirs considering the confinement effect. To study the microscopic physical mechanisms, the confinement effect is characterized by properties shift and capillarity and introduced into the flash calculation to obtain the phase equilibrium of mixture fluids (tight oil/CO2/N2) in tight porous media. The results indicate that the injected nitrogen gas could effectively maintain the reservoir pressure, while it also weakens the effects of the CO2 injection recovery mechanisms, notably diffusivity and viscosity reduction. In addition, a dual‐pore tight oil reservoir model is set up to investigate the CO2/N2 injection with ultra‐low permeability and hydraulic fracturing. The basic CO2 injection parameters are optimized by the orthogonal method. Based on CO2 injection process, three injection schemes of CO2/N2 injection, which are mixed‐gas injection, CO2‐alternating‐N2 (CAN) injection, and N2‐alternating‐CO2 (NAC) injection, were investigated and a comparative analysis was made for the pressure distribution, CO2 mole fraction distribution, and cumulative oil production. Based on this analysis, the CAN injection process proved to be the best injection scheme. A parametric analysis further suggested that the nitrogen gas injection rate was the most important factor. Besides, the effect of gravity drainage, reservoir permeability, nature fractures, and permeability heterogeneity on the oil production of CAN injection process were also investigated in detail. The results show that tight oil reservoir with better vertical connectivity, poor fracture growth, and higher heterogeneity is more favorable for the CO2/N2 injection process.

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“…The properties data of oil components have been listed in Table . The other physiochemical properties of tight oil could be found in references …”

Section: Microscopic Physical Mechanisms Of Nitrogen Gasmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Investigation of CO₂/N₂ injection in tight oil reservoirs with confinement effect

Wang

et al. 2019

Energy Science & Engineering

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“…However, little research has been done on the difference recovery mechanisms of CO 2 injection in tight oil reservoirs. CO 2 injection has been proved as the effective way to enhance tight oil recovery . CO 2 ‐based enhanced oil recovery techniques have been widely used in conventional reservoirs, and the recovery mechanisms have been revealed.…”

Section: Introductionmentioning

confidence: 99%

“…CO 2 ‐based enhanced oil recovery techniques have been widely used in conventional reservoirs, and the recovery mechanisms have been revealed. The main mechanisms of CO 2 injection include oil viscosity reduction, oil swelling, vaporization and extraction of lighter hydrocarbon components, dissolved gas drive aided by gravity drainage, and reduction of two‐phase interfacial tensions to achieve misciblility; (6) permeability improvement by acidification effect . However, the recovery mechanisms of CO 2 injection would be different because of the nanoscale pores, which have a great effect on fluid properties.…”

Section: Introductionmentioning

confidence: 99%

“…The main mechanisms of CO 2 injection include (1) oil viscosity reduction, (2) oil swelling, (3) vaporization and extraction of lighter hydrocarbon components, (4) dissolved gas drive aided by gravity drainage, and (5) reduction of two-phase interfacial tensions to achieve misciblility; (6) permeability improvement by acidification effect. 32,34 However, the recovery mechanisms of CO 2 injection would be different because of the nanoscale pores, which have a great effect on fluid properties. And the recovery mechanisms of CO 2 injection should be recognized and re-evaluated in tight porous media.…”

Section: Introductionmentioning

confidence: 99%

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Impact of fluid property shift and capillarity on the recovery mechanisms of CO₂injection in tight oil reservoirs

Sarma

et al. 2019

Greenhouse Gases

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The phase equilibria with the confinement effect could shift in nano‐pores, which could have a great impact on the recovery mechanisms of CO2 injection in tight oil reservoirs; this has not been systematically studied. In this paper, the confinement effect with property shift and capillarity effect is introduced into the flash calculation of confined fluids. The Soave modification of the Redlich–Kwong equation of state is extended by the molecular‐wall collision parameter to describe the shifted pressure–volume–temperature properties of confined fluid, and the Young–Laplace equation is applied to evaluate the capillary pressure. This developed model could effectively be applied for phase equilibrium calculation in tight porous media because of the verification of experimental results. A binary mixture is investigated to study the different effect of capillary pressure and property shift on phase equilibria. Subsequently, a typical hydrocarbon fluid from Middle Bakken tight oil reservoirs is studied with CO2 injection. Results illustrate that the confinement effect could play an increasingly important part in the phase equilibrium state. The CO2 solubility and mass transfer driving force in tiny pores would be greater than those in large pores under the same conditions. The gas phase saturation would be smaller with the same compositions, which could extend the single‐phase region of fluid flow in porous media. Furthermore, bubble‐point pressure, the minimum miscible pressure of CO2/hydrocarbon, and the viscosity of tight oil dissolved with CO2 both decrease with the pore size, which has a good influence on tight oil recovery. In general, the confinement effect could effectively reinforce the recovery mechanisms of CO2 injection, which is conducive to the enhancement of tight oil recovery. © 2019 Society of Chemical Industry and John Wiley & Sons, Ltd.

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Process simulation of CO₂ capture from CO₂‐EOR associated petroleum gas with aqueous MEA and MDEA solvents

Liu

Zhang

Wang

et al. 2019

Energy Science & Engineering

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Associated petroleum gas produced by CO2‐enhanced oil recovery (CO2‐EOR) has a complex composition, high CO2 content, and is unstable. To date, no integrated process simulation for CO2 capture of the EOR associated petroleum gas has been developed. Based on the analysis of the associated petroleum gas obtained from the Shengli oilfield, a new full‐simulation model of CO2 capture from 100 000 Nm3/d of the associated petroleum gas was developed for the process design of chemical absorption of blended amine solvents and an analysis of the relationship between different process parameters and the targeted result—low circulation flow and energy consumption—was performed using Aspen Plus (Version 8.6). A 90% CO2 removal rate was achieved using 0.2 mol CO2/mol of a blended amine as solvent, with an energy consumption of 3.16 GJ/tCO2. By analyzing the influence of absorption pressure, temperature, and packing height on the circulation flow, the influence of absorption and desorption pressure on the energy consumption of the system was determined. It can be concluded that the optimal parameters are as follows: packing height of absorption column, 10 m; absorption temperature, 308.15 K; desorption pressure, 0.12 MPa; and CO2 loading, 0.2 mol/mol of lean solvent, with an absorption pressure of 0.3‐0.6 MPa.

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CO2-EOR mechanisms in huff-n-puff operations in shale oil reservoirs based on history matching results

Cited by 85 publications

References 4 publications

Investigation of CO₂/N₂ injection in tight oil reservoirs with confinement effect

Investigation of CO₂/N₂ injection in tight oil reservoirs with confinement effect

Impact of fluid property shift and capillarity on the recovery mechanisms of CO₂injection in tight oil reservoirs

Process simulation of CO₂ capture from CO₂‐EOR associated petroleum gas with aqueous MEA and MDEA solvents

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CO2-EOR mechanisms in huff-n-puff operations in shale oil reservoirs based on history matching results

Cited by 85 publications

References 4 publications

Investigation of CO2/N2 injection in tight oil reservoirs with confinement effect

Investigation of CO2/N2 injection in tight oil reservoirs with confinement effect

Impact of fluid property shift and capillarity on the recovery mechanisms of CO2injection in tight oil reservoirs

Process simulation of CO2 capture from CO2‐EOR associated petroleum gas with aqueous MEA and MDEA solvents

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Investigation of CO₂/N₂ injection in tight oil reservoirs with confinement effect

Investigation of CO₂/N₂ injection in tight oil reservoirs with confinement effect

Impact of fluid property shift and capillarity on the recovery mechanisms of CO₂injection in tight oil reservoirs

Process simulation of CO₂ capture from CO₂‐EOR associated petroleum gas with aqueous MEA and MDEA solvents