Critical review of field EOR projects in shale and tight reservoirs

Sheng, James J.

doi:10.1016/j.petrol.2017.09.022

Cited by 219 publications

(106 citation statements)

References 31 publications

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“…In Equation (5), we applied the Sigmund's work to calculate the diffusion coefficient of component i (D il ), which is valid for both oil and gas phases [38,39]. τ is tortuosity.…”

Section: Flow Governing Equationsmentioning

confidence: 99%

Simulation Study of CO2 Huff-n-Puff in Tight Oil Reservoirs Considering Molecular Diffusion and Adsorption

Zhang

2019

Energies

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CO2 injection has great potentials to improve the oil production for the fractured tight oil reservoirs. However, Current works mainly focus on its operation processes; full examination of CO2 molecular diffusion and adsorption was still limited in the petroleum industry. To fill this gap, we proposed an efficient method to accurately and comprehensively evaluate the efficiency of CO2-EOR process. We first calculated the confined fluid properties with the nanopore effects. Subsequently, a reservoir simulation model was built based on the experiment test of the Eagle Ford core sample. History matching was performed for the model validation. After that, we examined the effects of adsorption and molecular diffusion on the multi-well production with CO2 injection. Results illustrate that in the CO2-EOR process, the molecular diffusion has a positive impact on the oil production, while adsorption negatively impacts the well production, indicating that the mechanisms should be reasonably incorporated in the simulation analysis. Additionally, simulation results show that the mechanisms of molecular diffusion and adsorption make great contributions to the capacity of CO2 storage in tight formations. This study provides a strong basis to reasonably forecast the long-term production during CO2 Huff-n-Puff process.

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“…In Equation (5), we applied the Sigmund's work to calculate the diffusion coefficient of component i (D il ), which is valid for both oil and gas phases [38,39]. τ is tortuosity.…”

Section: Flow Governing Equationsmentioning

confidence: 99%

Simulation Study of CO2 Huff-n-Puff in Tight Oil Reservoirs Considering Molecular Diffusion and Adsorption

Zhang

2019

Energies

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“…The asphalthene content in the crude oil was 4.96 wt %. The density of oil sample was 0.78 g/cm 3 with viscosity of 8.2 mPa·s at temperature of 50 • C. Oil sample used in the experiment was degassed and centrifuged at 5000 rpm for two hours to avoid any inaccuracy during zeta potential tests.…”

Section: Oilmentioning

confidence: 99%

“…Due to the decline of oil and natural gas production from conventional reservoirs, the gravitation towards unconventional resources development receives broad scientific interest [2]. Such resources are reserved in shale rocks with nano-Darcies level permeability, although the presence of small natural fracture may trigger an effective permeability higher than the order of nano-Darcies [3]. Due to the extremely low matrix permeability, the production is associated with hydraulic fracturing, which can activate pre-existing fractures and create new fractures, thus enhancing permeability by improving the connectivity [2].…”

Section: Introductionmentioning

confidence: 99%

Drivers of Wettability Alteration for Oil/Brine/Kaolinite System: Implications for Hydraulic Fracturing Fluids Uptake in Shale Rocks

et al. 2018

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Abstract:Hydraulic fracturing technique is of vital importance to effectively develop unconventional shale resources. However, the low recovery of hydraulic fracturing fluids appears to be the main challenge from both technical and environmental perspectives in the last decade. While capillary forces account for the low recovery of hydraulic fracturing fluids, the controlling factor(s) of contact angle, thus wettability, has yet to be clearly defined. We hypothesized that the interaction of oil/brine and brine/rock interfaces governs the wettability of system, which can be interpreted using Derjaguin-Landau-Verwey-Overbeek (DLVO) and surface complexation modelling. To test our hypothesis, we measured a suit of zeta potential of oil/brines and brine/minerals, and tested the effect of ion type (NaCl, MgCl 2 and CaCl 2 ) and concentrations (0.1, 1, and 5 wt %). Moreover, we calculated the disjoining pressure of the oil/brine/mineral systems and compared with geochemical modelling predictions. Our results show that cation type and salinity governed oil/brine/minerals wettability. Divalent cations (Ca 2+ and Mg 2+ ) compressed the electrical double layer, and electrostatically linked oil and clays, thus increasing the adhesion between oil and minerals, triggering an oil-wet system. Increasing salinity also compressed the double layer, and increased the site density of oppositely charged surface species which made oil and clay link more strongly. Our results suggest that increasing salinity and divalent cations concentration likely decrease water uptake in shale oil reservoirs, thus de-risking the hydraulic fracturing induced formation damage. Combining DLVO and surface complexation modelling can delineate the interaction of oil/brine/minerals, thus wettability. Therefore, the relative contribution of capillary forces with respect to water uptake into shale reservoirs, and the possible impairment of hydrocarbon production from conventional reservoirs can be quantified.

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“…[34][35][36][37][38][39][40][41] Sheng (2017) reviewed and discussed previous experiments and simulations on gas injection recovery in shale reservoirs. 42 He concludes that gas injection in shale reservoirs is more practical and effective than other EOR methods. The simulation results reect the CO 2 HnP performance to some extent.…”

Section: Introductionmentioning

confidence: 99%

Experimental investigation of shale oil recovery from Qianjiang core samples by the CO₂ huff-n-puff EOR method

Wang

et al. 2019

RSC Adv.

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CO 2 Huff-n-Puff (HnP) is an effective technique for enhancing oil recovery (EOR) that can be applied to shale oil reservoirs faced with poor natural productivity and low water injectivity. The main objective of this study is to investigate the interactions of CO 2 and formation crude oil, and evaluate the CO 2 HnP performance in shale oil reservoirs in the Qianjiang depression in China. In this study, the variation rules of oil phase behavior, viscosity, saturation pressure, and swelling factor at different CO 2 contents of 0 to 65% were studied. A series of HnP experiments were conducted. The factors affecting the oil recovery were discussed, and Nuclear Magnetic Resonance (NMR) tests were conducted on core samples at different stages of the HnP process. The results show that the injected CO 2 can make an positive change in the crude oil phase behavior. The oil-gas two-phase region enlarges and the saturation pressure increases as more CO 2 is dissolved in the formation oil, which is beneficial to oil production. The dissolution of CO 2 in the oil phase increased the oil swelling degree by 1.492 times, and the viscosity decreased from 1.944 to 0.453 mPa s. The HnP experimental results demonstrate that the soaking time should be determined based on the injection pressure. Miscible conditions is a viable option for CO 2 HnP as 10% more oil can be produced using miscible HnP and save more than half of the soaking time.The results illustrate that fracture is the most important factor affecting oil recovery, and the performance of HnP EOR on core samples with fractures is almost 25% better than those without fractures. However, the core matrix permeability has an almost negligible effect on the performance of CO 2 HnP. The NMR tests show that the oil recovered in the first cycle was dominated by macropores and mesopores, followed by small pores. In the latter HnP cycles, the oil in small pores and micropores becomes the main oil-producing area. This study may provide a better understanding of the CO 2 HnP enhanced recovery strategy for shale reservoirs.

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Critical review of field EOR projects in shale and tight reservoirs

Cited by 219 publications

References 31 publications

Simulation Study of CO2 Huff-n-Puff in Tight Oil Reservoirs Considering Molecular Diffusion and Adsorption

Simulation Study of CO2 Huff-n-Puff in Tight Oil Reservoirs Considering Molecular Diffusion and Adsorption

Drivers of Wettability Alteration for Oil/Brine/Kaolinite System: Implications for Hydraulic Fracturing Fluids Uptake in Shale Rocks

Experimental investigation of shale oil recovery from Qianjiang core samples by the CO₂ huff-n-puff EOR method

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Critical review of field EOR projects in shale and tight reservoirs

Cited by 219 publications

References 31 publications

Simulation Study of CO2 Huff-n-Puff in Tight Oil Reservoirs Considering Molecular Diffusion and Adsorption

Simulation Study of CO2 Huff-n-Puff in Tight Oil Reservoirs Considering Molecular Diffusion and Adsorption

Drivers of Wettability Alteration for Oil/Brine/Kaolinite System: Implications for Hydraulic Fracturing Fluids Uptake in Shale Rocks

Experimental investigation of shale oil recovery from Qianjiang core samples by the CO2 huff-n-puff EOR method

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Experimental investigation of shale oil recovery from Qianjiang core samples by the CO₂ huff-n-puff EOR method