Energies

Research

22 pages, 18467 KiB

Open AccessArticle

Co-Optimization of Operational and Intelligent Completion Parameters of CO₂ Water-Alternating-Gas Injection Processes in Carbonate Reservoirs

by Xili Deng, Jingxuan Wang, Xiangguo Zhao, Liangyu Rao, Yongbin Zhao and Xiaofei Sun

Energies 2025, 18(2), 375; https://doi.org/10.3390/en18020375 - 16 Jan 2025

Viewed by 497

Abstract

Recently, maximum reservoir contacting (MRC) wells have attracted more and more attention and have been gradually applied to CO₂ WAG injections. During the use of MRC wells for CO₂ WAG injections, intelligent completions are commonly considered to control CO₂ breakthroughs. [...] Read more.

Recently, maximum reservoir contacting (MRC) wells have attracted more and more attention and have been gradually applied to CO₂ WAG injections. During the use of MRC wells for CO₂ WAG injections, intelligent completions are commonly considered to control CO₂ breakthroughs. However, the design of the operational and intelligent completion parameters is a complicated process and there are no studies on the co-optimization of the operational and intelligent completion parameters for CO₂ WAG processes. This study outlines an approach to enhance the oil recovery from CO₂ WAG injection processes through the co-optimization of the operational and intelligent completion parameters of MRC wells in a carbonate reservoir. First, a simulation method is developed by using Petrel and Intersect. Then, a series of simulations are performed to prove the viability of intelligent completions and to investigate the effects of the timing and duration of the CO₂ WAG injection, as well as the type, number, and placement of intelligent completion devices on the performance of a CO₂ WAG injection by MRC wells. Finally, the imperialist competitive algorithm is used to co-optimize the operational and intelligent completion parameters for MRC wells. The results show that compared with the spiral inflow control device (SICD), autonomous inflow control device (AICD), labyrinth inflow control device (LICD), and annular interval control valve (AICV), the nozzle inflow control device (NICD) is the best type of intelligent completion device for MRC wells. There is an optimal installation timing, inflow area, and number of NICDs for a CO₂ WAG injection by MRC wells. The NICDs need to be placed based on the permeability distribution. The oil recovery for the optimal case with the NICDs reached 46.43%, which is an increase of 3.8% over that of the base case with a conventional completion. In addition, compared with the non-uniformity coefficient of the base case (11.7), the non-uniformity coefficient of the optimal case with the NICDs decreased to 4.21. This is the first time that the co-optimization of the operational and intelligent completion parameters of a CO₂ WAG injection has been reported, which adds more information about the practical applications of MRC wells in CO₂ WAG injections for enhancing oil recovery in carbonate reservoirs. Full article

(This article belongs to the Special Issue Failure and Multiphysical Fields in Geo-Energy)

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14 pages, 4767 KiB

Open AccessArticle

Experimental Assessment of Magnetic Nanofluid Injection in High-Salinity and Heavy-Crude-Saturated Sandstone: Mitigation of Formation Damage

by Jimena Lizeth Gómez-Delgado, Nelson Gutierrez-Niño, Luis Felipe Carrillo-Moreno, Raúl Andres Martínez-López, Nicolás Santos-Santos and Enrique Mejía-Ospino

Energies 2025, 18(1), 212; https://doi.org/10.3390/en18010212 - 6 Jan 2025

Viewed by 464

Abstract

The depletion of conventional oil reserves has intensified the search for enhanced oil recovery (EOR) techniques. Recently, nanoparticle research has focused on graphene oxide-based materials, revealing a critical challenge in their practical application. Laboratory investigations have consistently demonstrated that these nanoparticles have significant [...] Read more.

The depletion of conventional oil reserves has intensified the search for enhanced oil recovery (EOR) techniques. Recently, nanoparticle research has focused on graphene oxide-based materials, revealing a critical challenge in their practical application. Laboratory investigations have consistently demonstrated that these nanoparticles have significant potential for formation damage, a critical limitation that substantially constrains their potential field implementation. This research addresses a critical challenge in EOR: developing magnetic graphene oxide nanoparticles (MGONs) that can traverse rock formations without causing formation damage. MGONs were synthesized and stabilized in formation brine with a high total dissolved solids (TDS) content with a xanthan gum polymer. Two coreflooding experiments were conducted on sandstone cores. The first experiment on high-permeability sandstone (843 mD) showed no formation damage; instead, permeability increased to 935 mD after MGON injection. Irreducible water saturation (S_wirr) and residual oil saturation (S_or) were 25.1% and 31.5%, respectively. The second experiment on lower-permeability rock (231.3 mD) evaluated nanoparticle retention. The results showed that 0.09511 mg of MGONs was adsorbed per gram of rock under dynamic conditions. Iron concentration in effluents stabilized after 3 pore volumes, indicating steady-state adsorption. The successful synthesis, stability in high-TDS brine, favorable interfacial properties, and positive effects observed in coreflooding experiments collectively highlight MGONs’ potential as a viable solution for enhancing oil recovery in challenging reservoirs, without causing formation damage. Full article

(This article belongs to the Special Issue Failure and Multiphysical Fields in Geo-Energy)

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27 pages, 19982 KiB

Open AccessArticle

Investigation of the CO₂ Pre-Fracturing Mechanism for Enhancing Fracture Propagation and Stimulated Reservoir Volume in Ultra-Deep Oil Reservoirs

by Liming Liu, Ran Ding, Enqing Chen and Cheng Zhang

Energies 2025, 18(1), 96; https://doi.org/10.3390/en18010096 - 30 Dec 2024

Viewed by 490

Abstract

CO₂ pre-fracturing is an innovative technique for enhancing oil and gas production in unconventional reservoirs. Despite its potential, the mechanisms of CO₂ pre-fracturing influencing fracture propagation, particularly in ultra-deep reservoirs, remain inadequately understood. This study investigates the CO₂ pre-fracturing process [...] Read more.

CO₂ pre-fracturing is an innovative technique for enhancing oil and gas production in unconventional reservoirs. Despite its potential, the mechanisms of CO₂ pre-fracturing influencing fracture propagation, particularly in ultra-deep reservoirs, remain inadequately understood. This study investigates the CO₂ pre-fracturing process in ultra-deep sandstone reservoirs of the central Junggar Basin. A 3D geomechanical model was established using RFPA3D-HF based on rock mechanical parameters from laboratory experiments. The study examines the effect of in situ horizontal stress differences, CO₂ pre-injection volume, and slickwater injection rate on fracture complexity index (FCI) and stimulated reservoir volume (SRV). The results reveal that in situ horizontal stress differences are the primary factor influencing fracture propagation. In ultra-deep reservoirs, high horizontal stress difference hinders fracture deflection and bifurcation during slickwater fracturing. CO₂ pre-fracturing, through the pre-injection of CO₂, reduces formation breakdown pressure and increases reservoir pore pressure due to its low viscosity and high permeability, effectively mitigating the effect of high horizontal stress differences and significantly enhancing fracturing effectiveness. Furthermore, appropriately increasing the CO₂ pre-injection volume and slickwater injection rate can increase fracture complexity, resulting in a larger SRV. Notably, adjusting the CO₂ pre-injection volume is more effective than adjusting slickwater injection rate in enhancing oil production. This study provides scientific evidence for selecting construction parameters and optimizing oil recovery through CO₂ pre-fracturing technology in deep unconventional oil reservoirs and offers new insights into CO₂ utilization and storage. Full article

(This article belongs to the Special Issue Failure and Multiphysical Fields in Geo-Energy)

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19 pages, 7494 KiB

Open AccessArticle

Formation and Evolution of Multi-Genetic Overpressure and Its Effect on Hydrocarbon Accumulation in the Dabei Area, Kuqa Depression, Tarim Basin, China

by Chenxi Wen and Zhenliang Wang

Energies 2024, 17(24), 6263; https://doi.org/10.3390/en17246263 - 12 Dec 2024

Viewed by 646

Abstract

The Kuqa Foreland Basin is an important hydrocarbon-producing basin in western China. The Dabei area is an important zone for hydrocarbon accumulation. High fluid overpressures in the Lower Cretaceous Bashijiqike Formation are related to multi-genetic processes. However, the formation and evolution of pressure [...] Read more.

The Kuqa Foreland Basin is an important hydrocarbon-producing basin in western China. The Dabei area is an important zone for hydrocarbon accumulation. High fluid overpressures in the Lower Cretaceous Bashijiqike Formation are related to multi-genetic processes. However, the formation and evolution of pressure remain unclear, hindering the further development of oil and gas migration and accumulation. In this study, the overpressure distribution is described based on a drill stem test and mud density data. The formation and quantification of multi-genetic overpressure were evaluated based on well-logging data and basin simulation technology (Ansys Workbench). The coupling evolution of multi-genetic overpressure was examined based on the basin simulation technique. Finally, the influence of overpressure on hydrocarbon accumulation was explored. The results showed that the residual pressure of the Bashijiqike Formation in the Dabei area ranged from 40 to 60 MPa. The main causes of pressure in the Bashijiqike Formation in the Dabei area were disequilibrium compaction overpressure (2–6 MPa, contribution of 8–15%), tectonic compression overpressure (10 MPa, contribution of 30%), and fracture transfer overpressure (15–20 MPa, contribution of 8–15%). With respect to the evolution process of multiple pressures in the Bashijiqike Formation in the Dabei region, at 0–23.3 Ma, the overpressure due to disequilibrium compaction was <10 MPa and increased slowly to 18 MPa at 2.48–23.3 Ma. At 2.48 Ma, the tectonic compression was enhanced, and the residual pressure reached ~50 MPa. At 1.75–2.48 Ma, fracture activity was enhanced, leading to the generation of fracture transfer overpressure. Under these conditions, the residual pressure exceeded 60 MPa. Finally, the Bashijiqike Formation in the Dabei area is a favorable area for vertical and lateral migration of oil and gas. This study is of great significance to the formation and evolution of multi-origin overpressure in the same basin type and its influence on oil and gas accumulation. Full article

(This article belongs to the Special Issue Failure and Multiphysical Fields in Geo-Energy)

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15 pages, 4105 KiB

Open AccessArticle

Experimental Investigation of CO₂ Huff-and-Puff Enhanced Oil Recovery in Fractured Low-Permeability Reservoirs: Core-Scale to Pore-Scale

by Fenglan Zhao, Changhe Yang, Shijun Huang, Mingyang Yang, Haoyue Sun and Xinyang Chen

Energies 2024, 17(23), 6207; https://doi.org/10.3390/en17236207 - 9 Dec 2024

Viewed by 775

Abstract

CO₂ huff-n-puff is regarded as an effective method to improve the recovery of low permeability and tight oil reservoirs. To understand the impact of CO₂ huff-n-puff on crude oil mobilization in tight reservoirs with different fracture scales, this study conducted CO [...] Read more.

CO₂ huff-n-puff is regarded as an effective method to improve the recovery of low permeability and tight oil reservoirs. To understand the impact of CO₂ huff-n-puff on crude oil mobilization in tight reservoirs with different fracture scales, this study conducted CO₂ huff-n-puff nuclear magnetic resonance (NMR) and microscopic visualization experiments, focusing on how varying fracture apertures and densities affect the efficiency of the CO₂ huff-n-puff. The results show that in scenarios with a single fracture, larger fracture apertures significantly boost oil mobilization within the fracture and the surrounding matrix. For instance, increasing the aperture from 20 μm to 70 μm improved the recovery factor by 9.20%. In environments with multiple fractures, greater fracture density enhances reservoir connectivity, and increases the CO₂ sweep area, and the complex fracture model shows a 4.26% increase in matrix utilization compared to the simple fracture model. Notably, the improvement in recovery due to multi-scale fractures is most significant during the first two huff-and-puff cycles, with diminishing returns in subsequent cycles. Overall, increasing both fracture size and density effectively enhances crude oil mobilization in tight reservoirs. These findings provide valuable insights into improving the recovery efficiency of CO₂ huff-and-puff techniques in tight oil reservoirs. Full article

(This article belongs to the Special Issue Failure and Multiphysical Fields in Geo-Energy)

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12 pages, 2411 KiB

Open AccessArticle

Real-Time Experimental Monitoring for Water Absorption Evolution Behaviors of Sandstone in Mogao Grottoes, China

by Nai Hao, Yongliang Wang, Xiaochong Wu, Yifeng Duan, Panshun Li and Manchao He

Energies 2022, 15(22), 8504; https://doi.org/10.3390/en15228504 - 14 Nov 2022

Cited by 5 | Viewed by 1658

Abstract

Rock mass has typical pore structure, and the induced coupling effects of fluid and solid matrix appear in the disaster evolution process of deep energy exploitation and overground rock hydration. As a representative case, influenced by the water absorption environment, the surrounding rock [...] Read more.

Rock mass has typical pore structure, and the induced coupling effects of fluid and solid matrix appear in the disaster evolution process of deep energy exploitation and overground rock hydration. As a representative case, influenced by the water absorption environment, the surrounding rock and murals of Mogao Grottoes produce hydration diseases, which may be related to unclear interaction mechanisms between the surrounding rock and water. In this study, the self-developed physical experimental system for real-time experimental monitoring was applied to test the water absorption evolution behaviors of sandstone. The experimental results showed that the water evaporation of the rock sample during the process of water absorption could be measured through this well-designed physical experimental system, and the actual water absorption of the rock sample is the difference between the decrease of water in the water storage bucket, measured by the balance and the water evaporation in the process of experiment; by drawing the actual water absorption curve of the rock sample, the time when the water absorption of the rock sample reaches saturation could be determined accurately; and the curve of water absorption with time could be expressed as an exponential function. The experimental techniques and methods in this study provide a feasible research idea for studying the water absorption evolution behaviors and mechanisms of the surrounding rock weathering when it meets water, and have significance for revealing the disease mechanisms of the surrounding sandstone in Mogao Grottoes, China. Full article

(This article belongs to the Special Issue Failure and Multiphysical Fields in Geo-Energy)

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15 pages, 7349 KiB

Open AccessArticle

Deflection of Hydraulic Fractures and Shear Stress Disturbance Considering Thermal Effects: A Numerical Case Study

by Nana Liu and Yongliang Wang

Energies 2022, 15(13), 4888; https://doi.org/10.3390/en15134888 - 4 Jul 2022

Cited by 1 | Viewed by 1939

Abstract

Quantitative characterization of propagation behaviors and morphology of hydraulic fractures is crucial for controlling and optimizing hydrofracturing effects. To study the disturbance deflection behaviors of multiple hydraulic fractures, a three-dimensional field-scale numerical model for multistage fracturing is established to study the shear stress [...] Read more.

Quantitative characterization of propagation behaviors and morphology of hydraulic fractures is crucial for controlling and optimizing hydrofracturing effects. To study the disturbance deflection behaviors of multiple hydraulic fractures, a three-dimensional field-scale numerical model for multistage fracturing is established to study the shear stress disturbance and unstable propagation behavior of hydraulic fractures under different perforation cluster spacing. In the model, the thermal diffusion, fluid flow and deformation in reservoirs are considered to describe the thermal-hydro-mechanical coupling. In the numerical case study, the derived results show that the thermal effect between fracturing fluid and rock matrix is an important factor affecting fracture propagation, and thermal effects may increase the extent of fracture propagation. The size of stress shadow areas and the deflection of hydraulic fractures will increase with a decrease in multiple perforation cluster spacing in horizontal wells. The shear stress disturbance caused by fracture propagation is superimposed in multiple fractures, resulting in the stress shadow effect and deflection of fractures. Full article

(This article belongs to the Special Issue Failure and Multiphysical Fields in Geo-Energy)

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15 pages, 3524 KiB

Open AccessArticle

Self-Supervised Railway Surface Defect Detection with Defect Removal Variational Autoencoders

by Yongzhi Min and Yaxing Li

Energies 2022, 15(10), 3592; https://doi.org/10.3390/en15103592 - 13 May 2022

Cited by 13 | Viewed by 2709

Abstract

In railway surface defect detection applications, supervised deep learning methods suffer from the problems of insufficient defect samples and an imbalance between positive and negative samples. To overcome these problems, we propose a lightweight two-stage architecture including the railway cropping network (RC-Net) and [...] Read more.

In railway surface defect detection applications, supervised deep learning methods suffer from the problems of insufficient defect samples and an imbalance between positive and negative samples. To overcome these problems, we propose a lightweight two-stage architecture including the railway cropping network (RC-Net) and defects removal variational autoencoder (DR-VAE), which requires only normal samples for training to achieve defect detection. First, we design a simple and effective RC-Net to extract railway surfaces accurately from railway inspection images. Second, the DR-VAE is proposed for background reconstruction of railway surface images to detect defects by self-supervised learning. Specifically, during the training process, DR-VAE contains a defect random mask module (D-RM) to generate self-supervised signals and uses a structural similarity index measure (SSIM) as pixel loss. In addition, the decoder of DR-VAE also acts as a discriminator to implement introspective adversarial training. In the inference stage, we reduce the random error of reconstruction by introducing a distribution capacity attenuation factor, and finally use the residuals of the original and reconstructed images to achieve segmentation of the defects. The experiments, including core parameter exploration and comparison with other models, indicate that the model can achieve a high detection accuracy. Full article

(This article belongs to the Special Issue Failure and Multiphysical Fields in Geo-Energy)

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