Study and Mechanism Analysis on Dynamic Shrinkage of Bottom Sediments in Salt Cavern Gas Storage

Wu, Benhong; Zhang, Mengchuan; Deng, Weibing; Que, Junren; Liu, Wei; Zhou, Fujian; Wang, Qing; Li, Yuan; Liang, Tianbo

doi:10.3390/pr10081511

Cited by 3 publications

(3 citation statements)

References 29 publications

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“…There was nonuniform etching on the rock slab after multistage alternating injection of the cross-linked acid and guar-based solution, but the degree of nonuniform etching was lower. More obvious [27,28] etching grooves formed after multistage alternating injection of gelled acid and cross-linked guar, cross-linked acid and gelled acid, and cross-linked acid and cross-linked guar. This etched groove greatly enhanced the nonuniform etching degree of the fracture wall [29], which hindered the acid-etched fracture from completely closing under the closing pressure after the acid fracturing stimulation, thus forming a high-speed channel for the flow of oil and gas.…”

Section: Acid Etching Simulation Resultsmentioning

confidence: 99%

Acid System and Stimulation Efficiency of Multistage Acid Fracturing in Porous Carbonate Reservoirs

et al. 2022

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With little to no natural fracture development and the high calcite content in porous carbonate reservoirs, for multistage acid fracturing, different fluids are used to form a viscous fingering in the fracture, thus enhancing the degree of nonuniform etching. However, existing studies on multistage acid fracturing mainly focused on the combination of fracturing fluid and acid, which is less specific for porous carbonate rocks. Here, the rheological properties of five fluids, including guar-based fluid, cross-linked guar, gelled acid, cross-linked acid, and diverting acid, were studied at each temperature condition, and the viscosity relationship between each fluid was clarified. Based on the rheological properties, the differences between the seven liquid combinations on the etched morphology of the fracture walls were studied and analyzed. The conductivity of the seven acid-etched fractures under different closure stress was simulated. The experimental results showed that the viscosity relationships between the fluids at different temperatures were cross-linked guar > cross-linked acid > diverting acid (spent acid) > gelled acid > guar-based liquid > diverting acid (fresh acid). Because cross-linked acid has higher viscosity than gelled acid, it can form more obvious viscous fingering with a variety of liquids, which is more suitable for acid fracturing stimulation of porous carbonate reservoirs. In addition, the combination of cross-linked and diverting acids was screened out. The multistage alternate injection of this fluid combination could form tortuous and complex etching channels, and its acid-etching fracture conductivity was significantly higher than that of other fluid combinations at different closure stress. In this study, we optimized the fluid combination of porous carbonates and clarified the effect and mechanism of nonuniform etching to provide guidance for the fluid combination selection of multistage alternate acid fracturing process for porous carbonate reservoirs.

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Section: Acid Etching Simulation Resultsmentioning

confidence: 99%

Acid System and Stimulation Efficiency of Multistage Acid Fracturing in Porous Carbonate Reservoirs

et al. 2022

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“…In the initial phase, SCGS in China prioritized salt mines characterized by the high purity of salt rock, the considerable thickness of the salt layer, the minimal content of the insoluble matter within the strata, and sparse interlayers for construction purposes [1][2][3][4]. However, driven by the imperatives of economic and societal progress, particularly in light of the gas storage reservoir construction area in key consumption zones across central and eastern China, the establishment of SCGS necessitated a shift towards developing sites featuring multiple interlayers and elevated levels of IS [5][6][7][8].…”

Section: Introductionmentioning

confidence: 99%

Research on the Influencing Factors of the Void Volume of Insoluble Sediment in Salt Cavern Gas Storage

Sun,

Ding,

et al. 2024

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Utilizing voids of insoluble sediment (IS) to store gas is an effective way to improve the efficiency of salt cavern gas storage (SCGS) in China. In this study, a suitable method for predicting the void volume of insoluble sediments (VVISs) is established. This study explores three key factors affecting the VVISs through laboratory experiments. Firstly, in order to make the experimental results more in line with production realities, an analysis of the characteristics of IS in X SCGS was conducted to provide a basis for setting parameters for subsequent experiments. Secondly, experimental setups and methods for measuring the VVISs were designed. Finally, the experimental results were used to predict the VVISs in on-site cavity wells. The results indicate that the higher the proportion of quartz, illite, and large-grain particles in IS, the larger the VVISs. Under different parameters, the VVISs can account for approximately 10–40% of the IS accumulation volume. Different particle sizes can cause a variation of approximately 5–30% in the VVISs, while different mineral compositions can result in a difference of 6–23% in the VVISs. With increasing compaction pressure, the VVISs can decrease by around 5–80%. The prediction of the VVISs in on-site cavity wells shows a high degree of fit with empirical algorithms. This study can provide a reference basis for the utilization of the void space of IS in SCGS.

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“…The obtained results displayed favorable agreement with field monitoring outcomes. Moreover, the opening of hydraulic fractures can cause compression of the surrounding reservoir, leading to alterations in pore pressure and stress fields adjacent to the fracture [20,21]. Sun et al [22] employed the finite element method (FEM) to investigate hydraulic fracturing parameters in porous media, revealing a gradual decrease in fluid pressure within the fracture as the fracture length increases.…”

Section: Introductionmentioning

confidence: 99%

Study on the Fracture Propagation in Multi-Horizontal Well Hydraulic Fracturing

et al. 2023

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Multi-horizontal well hydraulic fracturing is a widely employed and highly effective method for stimulating tight and shale reservoirs. However, most existing studies primarily focus on investigating the impact of intra-well interference on fracture propagation while neglecting the influence of inter-well interference. Here, a multi-well hydraulic-fracture-propagation model is established to examine the effects of inter-well interference on fracture propagation within a multi-well system. In this study, based on the bilinear T-S criterion, the stiffness degradation is used to describe the damage and evolution process of fracture, the coupling process of fluid flow and solid damage and deformation is realized, and the dynamic distribution of inter-fracture flow is realized by using Kirchhoff function on the basis of the cohesive zone method (CZM) finite element model. Finally, the fracture-propagation model of multiple horizontal wells is established. Based on this model, the mechanism of inter-well interference on fracture propagation is studied, and the influence law of Young’s modulus and fracture displacement on fracture propagation in multi-wells is investigated. The results show that the reservoir can be divided into self-influence area, tension area and compression area according to the stress distribution state in the hydraulic fracture propagation of multi-wells. The propagation rate of hydraulic fractures in horizontal wells is significantly accelerated when they propagate to the local tension area generated by the fracture tip of neighboring wells, and rapidly decreases as the hydraulic fractures continue to propagate to the compression area of neighboring wells. Rocks with a lower Young’s modulus tend to be more plastic, forming hydraulic fractures with usually lower fracture lengths and usually larger fracture widths. The hydraulic fracture has an inhibitory effect on the propagation of fractures closer to each other in neighboring wells, and this inhibitory effect gradually increases as the distance decreases. The dominance of the dominant fracture to propagate in the self-influence area gradually decreases under inter-well and intra-well interference. As the dominant fracture propagates into the tension and compression areas of the neighboring well fractures, the feed fluid will show a brief rise and then eventually stabilize. This study quantifies the effect of inter-well interference on fracture propagation and lays the foundation for treatment optimization of small well spacing hydraulic fracturing.

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Study and Mechanism Analysis on Dynamic Shrinkage of Bottom Sediments in Salt Cavern Gas Storage

Cited by 3 publications

References 29 publications

Acid System and Stimulation Efficiency of Multistage Acid Fracturing in Porous Carbonate Reservoirs

Acid System and Stimulation Efficiency of Multistage Acid Fracturing in Porous Carbonate Reservoirs

Research on the Influencing Factors of the Void Volume of Insoluble Sediment in Salt Cavern Gas Storage

Study on the Fracture Propagation in Multi-Horizontal Well Hydraulic Fracturing

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