Experimental study of CO2 huff-n-puff in a tight conglomerate reservoir using true triaxial stress cell core fracturing and displacement system: A case study

Pu, Wanfen; Du, Daijun; Wang, Song; Zeng, Lingping; Feng, Runhua; Memon, Shoaib; Sarout, Joël; Varfolomeev, Mikhail A.; Sarmadivaleh, Mohammad; Xie, Quan

doi:10.1016/j.petrol.2020.108298

Cited by 20 publications

(12 citation statements)

References 37 publications

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“…Alfarge et al reported that the performance behavior of gas-EOR in ultralow reservoirs, particularly in the puff stage, is completely different from conventional reservoirs. In miscible gas injection, the most familiar mechanisms are diffusion, oil swelling, oil viscosity reduction, capillary force reduction, extraction, repressurization, density change, gas drive, and occasionally the combination of more than one mechanism. , However, in conventional reservoirs, the miscible gas system has a less significant mechanism in oil recovery. The maximum oil recovery of conventional reservoirs can be reached at a minimum miscibility pressure (MMP) .…”

Section: Gas-eor Mechanism In Shale/tight Reservoirsmentioning

confidence: 99%

“…A flooding system would rather be applied when the reservoir permeability is higher, at 0.03 md. Pu et al reported that, during the soaking procedure, the dominating mechanism distributing CO 2 in the formation is molecular diffusion. Sun et al simulated fractured horizontal wells of the middle Bakken oilfield by applying a CO 2 H-n-P model.…”

Section: Gas-eor Mechanism In Shale/tight Reservoirsmentioning

confidence: 99%

“…Pu et al 63 used a real triaxial stress cell core fracturing and displacement method to conduct an experiment mixing hydraulic fracturing with CO 2 H-n-P. CO 2 H-n-P is capable of boosting oil recovery in tight formations with an EOR of 29.2% of OOIP, according to experimental results. They built geochemical modeling to help understand the laboratory findings.…”

Section: Gas-eor Experimental Studiesmentioning

confidence: 99%

“…The cost of pilot studies is another existing challenge which is in excess of several million U.S. dollars, compared with laboratory research that can be performed at significantly lower costs. Researchers initiating valuable attempts to increase oil productivity of shale/tight oil reservoirs include the reports given in refs , , , , , , , , − . Most of the authors confirmed the success of the H-n-P application; however, they disagreed over the influence of some crucial mechanisms and key parameters, because of the lack of actual field data.…”

Section: Introductionmentioning

confidence: 99%

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Huff-n-Puff Technology for Enhanced Oil Recovery in Shale/Tight Oil Reservoirs: Progress, Gaps, and Perspectives

et al. 2021

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In recent times, particularly in the 21st century, there has been an alarming increase in the demand for global energy, along with continuous depletion in conventional oil reservoirs. This necessity has incentivized interested scholars and operators worldwide to seek alternative oil resources. To secure such accelerating energy demand, considerable effort has been directed toward the development of previously unconventional oil formations that, in past decades, had remained sidelined. Although shale oil reservoirs have seen tremendous success over the past decade, the continued challenges of rapidly declining oil flow rates and oil retention in the pores continuously persist. Substantial attempts have been made to improve shale-bypassed oil recovery; however, there is little data about the accessibility on recovery mechanisms, especially in the oil field. Furthermore, approachesparticularly, Huff-n-Puff (H-n-P) experiments using conventional proceduresfail to properly represent field conditions and they generate deceptive findings, because the utilized cores are not simulated under realistic reservoir conditions, leaving the significance of critical factors unclear. Therefore, this review study comprehensively and specifically discusses the feasibility of enhanced oil recovery (EOR) methods in unconventional oil reservoirs. Beside addressing the validity of the currently applied H-n-P technology in shale/tight oil reservoirs and underlining some critical gaps regarding laboratory results, modified technology is proposed in this paper for a better field future performance. The study is divided into sections, and each section analyzes the role of one specific H-n-P portion in detail, such as preferable injected solvents, their mechanisms, and critical factors affecting H-n-P recovery. The exceptions to this are the first and second sections, which provide a brief introduction about shale and tight oil reservoirs, a history of applied technology, and the method’s current problem statement. In the Introduction section, the authors will justify why this Review fills a critical gap in the field. Within the assessment study, great focus is given to the H-n-P technique, its parameters, and effective processes. In the final sections, carefully chosen experimental results and tools are reviewed to highlight the controversy and state “the gap”.

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Section: Gas-eor Mechanism In Shale/tight Reservoirsmentioning

confidence: 99%

Section: Gas-eor Mechanism In Shale/tight Reservoirsmentioning

confidence: 99%

Section: Gas-eor Experimental Studiesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Huff-n-Puff Technology for Enhanced Oil Recovery in Shale/Tight Oil Reservoirs: Progress, Gaps, and Perspectives

et al. 2021

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“…Tight oil, due to its vast reserves, has received great attention from the industry worldwide (Yan et al 2017a;Zhao et al 2017;Pu et al 2020). However, the recovery rate of tight oil is far from satisfactory.…”

Section: Introductionmentioning

confidence: 99%

Movement behavior of residual oil droplets and CO2: insights from molecular dynamics simulations

Luo

Liu

et al. 2022

J Petrol Explor Prod Technol

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After primary and secondary recovery of tight reservoirs, it becomes increasingly challenging to recover the remaining oil. Therefore, improving the recovery of the remaining oil is of great importance. Herein, molecular dynamics simulation (MD) of residual oil droplet movement behavior under CO2 displacement was conducted in a silica nanopores model. In this research, the movement behavior of CO2 in contact with residual oil droplets under different temperatures was analyzed, and the distribution of molecules number of CO2 and residual oil droplets was investigated. Then, the changes in pressure, kinetic energy, potential energy, van der Waals' force, Coulomb energy, long-range Coulomb potential, bond energy, and angular energy with time in the system after the contact between CO2 and residual oil droplets were studied. At last, the g(r) distribution of CO2–CO2, CO2-oil molecules, and oil molecules-oil molecules at different temperatures was deliberated. According to the results, the diffusion of CO2 can destroy residual oil droplets formed by the n-nonane and simultaneously peel off the n-nonane molecules that attach to SiO2 and graphene nanosheets (GN). The cutoff radius r of the CO2–CO2 is approximately 0.255 nm and that of the C–CO2 is 0.285 nm. The atomic force between CO2 and CO2 is relatively stronger. There is little effect caused by changing temperature on the radius where the maximum peak occurs in the radial distribution function (RDF)-g(r) of CO2–CO2 and C–CO2. The maximum peak of g(r) distribution of the CO2–CO2 in the system declines first and then rises with increasing temperature, while that of g(r) distribution of C–CO2 changes in the opposite way. At different temperatures, after the peak of g(r), its curve decreases with the increase in radius. The coordination number around C9H20 decreases, and the distribution of C9H20 becomes loose.

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Coupled Thermo-hydro-mechanical Simulation of Hydraulic Fracturing in Deep Reservoirs Using Finite-Discrete Element Method

et al. 2023

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Hydraulic fracturing (HF) is one of the most effective stimulation techniques to enhance reservoir permeability. The efficiency of an HF fluid injection depends on the pre-existing discontinuities or sources of heterogeneities and these features need to be considered in a HF operation treatment. Moreover, deep reservoirs are usually located in hot dry rocks (HDR). Hence, thermal conduction through the rock and fluid and advection and convective heat transfer in the fluid can affect the fluid–rock interaction. This study focuses on HF development in deep reservoirs under a high-temperature field. Two separate scenarios are considered: a reservoir containing discrete fracture networks (DFN) and another considering blocks in a matrix as conglomerate reservoirs (there is no relation between the scenarios considered). The study discusses each reservoir separately and simulates their thermo-hydro-mechanical (THM) behaviour using the combined finite-discrete element method (FDEM). First, the capabilities of the FDEM are verified against the existing analytical solutions, and then the FDEM is employed to model HF development. The effects of controlling factors, including flow rate, fluid kinematic viscosity and DFN aperture for jointed reservoirs and flow rate, fluid kinematic viscosity and block strength in conglomerate ones, are studied. The results show that the high fracture density DFNs strongly affect the HF propagation pattern and fluid pressure rise. Moreover, the DFN’s aperture significantly alters the HF treatment behaviour. The controlling factors are observed to influence the HF pattern strongly, and a successful HF treatment requires careful consideration of all the factors. In the conglomerate reservoirs, the strength of the blocks strongly dominates the HF mechanism, in which soft blocks break and allow for uniform fluid pressure distribution and longer HFs, while hard blocks stop fluid from flowing over longer distances accumulating high fluid pressure around the injection. This mechanism excessively breaks the matrix and reduces HF efficiency. Crack branching frequently occurs in conglomerate reservoirs due to thermal exchange between the blocks, matrix, and fluid.

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Experimental study of CO2 huff-n-puff in a tight conglomerate reservoir using true triaxial stress cell core fracturing and displacement system: A case study

Cited by 20 publications

References 37 publications

Huff-n-Puff Technology for Enhanced Oil Recovery in Shale/Tight Oil Reservoirs: Progress, Gaps, and Perspectives

Huff-n-Puff Technology for Enhanced Oil Recovery in Shale/Tight Oil Reservoirs: Progress, Gaps, and Perspectives

Movement behavior of residual oil droplets and CO2: insights from molecular dynamics simulations

Coupled Thermo-hydro-mechanical Simulation of Hydraulic Fracturing in Deep Reservoirs Using Finite-Discrete Element Method

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