Feasibility evaluation of hydraulic fracturing in hydrate-bearing sediments based on analytic hierarchy process-entropy method (AHP-EM)

Liu, Xiaoqiang; Wei-dong, Zhang; Qu, Zhanqing; Guo, Tiankui; Sun, Ying; Rabiei, Minou; Cao, Qinya

doi:10.1016/j.jngse.2020.103434

Cited by 89 publications

(41 citation statements)

References 31 publications

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“…The mechanical characteristics of the reservoir have a significant influence on fracture pressure, fracture width, and tensile shear failure mechanism, while the pore pressure gradient is the dominant factor controlling the fracture halflength and the influence degree of shear failure [31,41]. Due to the low permeability of clayey-silt sediments, the injected fracture fluid easily maintains the high pressure near the wellbore.…”

Section: Discussionmentioning

confidence: 99%

“…Previous studies that have verified brittleness index, mineral composition, hydrate saturation, fracturing fluid viscosity, and displacement are the main factors affecting the fracability of hydrate-bearing sediments [28][29][30]. Hydrate-bearing sandy sediments may form a cementing structure at higher saturations to possess consolidated rock-like mechanical properties due to the interconnected network of hydrates in pores or hydrates on sand grains [27,31]. Thus, hydrate-bearing sandy sediments could be artificially fractured using hydraulic fracturing [32].…”

Section: Introductionmentioning

confidence: 99%

“…To understand the fracture propagation characteristics of hydrate-bearing sediments, laboratory and numerical studies have been conducted [28][29][30][31][32]. Konno et al [28] combined hydraulic fracturing triaxial experiment and X-CT scanning to investigate fracture behavior.…”

Section: Introductionmentioning

confidence: 99%

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Experimental Study on the Propagation Characteristics of Hydraulic Fracture in Clayey-Silt Sediments

et al. 2021

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The low permeability of clayey-silt hydrate reservoirs in the South China Sea affects the thermal and pressure conductivity of the reservoir, which is difficult to spread to the far end of the wellbore and achieve commercial gas production. In this respect, enhancing the permeability to assist depressurization is necessary. Hydraulic fracturing is a promising reservoir stimulation method for gas hydrate reservoirs. Up to now, majorities of research focus on the fracability of hydrate-bearing sandy sediments, but the studies rarely involved fracture propagation characteristics of clayey-silt sediments in the hydrate dissociation area. In this paper, three sets of hydraulic fracturing experiments under different confining pressure were carried out using the clayey-silt sediments in the Shenhu Area. Computed tomographic (CT) images indicated that clayey-silt sediments could be artificially fractured, and the fracturing fluid could induce tensile fractures and local shear fractures. A multimorphological fracture zone occurred near the borehole. Furthermore, the greater the confining pressure imposed, the greater the breakdown pressure was, and the microfracture arose more easily. The fractures at the top were generally wider than those at the bottom with the same confining pressure. The experimental results could reveal the fracture initiation and propagation mechanism of clayey-silt sediments and provide theoretical support for hydraulic fracture in the hydrate dissociation area.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Experimental Study on the Propagation Characteristics of Hydraulic Fracture in Clayey-Silt Sediments

et al. 2021

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“…Then, the fracturing results indicate that there is a delayed effect during the fracture propagation process. In order to evaluate the fracturing performance of HBS, Liu et al 30 put forward a series of fracturing index parameters based on the analytic hierarchy process-entropy method. The feasibility of the parameters is proven by comparison to the fracturing experiment results.…”

Section: Introductionmentioning

confidence: 99%

Numerical Evaluation of Gas Hydrate Production Performance of the Depressurization and Backfilling with an In Situ Supplemental Heat Method

Zhang

et al. 2021

ACS Omega

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The depressurization and backfilling with an in situ supplemental heat method had been proposed to enhance the gas production of methane hydrate reservoir. This novel method is evaluated by a numerical simulator based on the finite volume method in this work. Based on the typical marine low-permeability hydrate-bearing sediments (HBS), a reservoir model with gas fracturing and CaO powder injection is constructed. The simulation results show that the stimulated fractures could effectively enhance the pressure drop effect. Moreover, the CaO injection could provide in situ heat simultaneously. Based on the sensitivity analysis of the equivalent permeability of fractures and the mass of CaO injection, it is found that a threshold fracture permeability exists for the increasing of gas production. The gas production increases with the equivalent permeability only when the permeability is smaller than the threshold value. Meanwhile, the more CaO are injected into reservoir, the larger volume of gas production. In general, this work theoretically quantifies the potential value of the depressurization and backfilling with an in situ supplemental heat method for marine gas hydrate recovery.

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“…At present, hydraulic fracturing is a key technique that can effectively stimulate well production and has been widely applied around the world [1][2][3]. However, the fracture initiation pressure (FIP) of traditional hydraulic fracturing is relatively high, and the propagation direction of the fracture is generally controlled by in situ stress [4], which often leads to the result that the formed hydraulic fracture fails to extend to the target area of the reservoir.…”

Section: Introductionmentioning

confidence: 99%

An Analytical Model for Fracture Initiation of Radial Drilling-Fracturing in Shale Formations

et al. 2021

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Radial drilling-fracturing, the combination of radial drilling and hydraulic fracturing, can guide fractures toward the target area and effectively enhance the recovery of the low permeable reservoir. In this paper, based on the stress superposition principle, we establish an analytical model to predict fracture initiation pressure (FIP) and the shale failure mode for radial drilling-fracturing applied in shale formations. In contrast with the former studies, this model can additionally consider the failure from shale beddings and is more applicable in the shale reservoir. The model classifies the shale failure into three modes and, respectively, gives the criterion for each failure mode. Then, a series of sensitivity analyses is conducted by examining effects of various parameters. By analyzing the variation characteristic of the initiation pressures required for three failure modes, the main conclusions are as follows. Firstly, matrix failure and shear failure along bedding tend to take place when the azimuth of radial borehole is moderate. Small and large azimuths are favorable for the occurrence of tensile failure along bedding. Secondly, a high ratio of horizontal in situ stress predisposes shale to generate matrix failure, and bedding tensile failure and bedding shear failure are apt to occur when the ratio of horizontal in situ stress is low. Thirdly, with the increasing intersection angle of the radial borehole wall and bedding plane, the failure mode apt to occur changes from bedding tensile failure to bedding shear failure and then to matrix failure. Fourthly, shale prefers to yield bedding shear failure under a small Biot coefficient and generate the other two failure modes when Biot coefficient is large. Fifthly, permeability coefficient virtually has no influence on the failure mode of shale. The research clarifies the fracture initiation characteristics of radial drilling-fracturing in shale formations and provides a reference for the field application of radial drilling-fracturing.

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Feasibility evaluation of hydraulic fracturing in hydrate-bearing sediments based on analytic hierarchy process-entropy method (AHP-EM)

Cited by 89 publications

References 31 publications

Experimental Study on the Propagation Characteristics of Hydraulic Fracture in Clayey-Silt Sediments

Experimental Study on the Propagation Characteristics of Hydraulic Fracture in Clayey-Silt Sediments

Numerical Evaluation of Gas Hydrate Production Performance of the Depressurization and Backfilling with an In Situ Supplemental Heat Method

An Analytical Model for Fracture Initiation of Radial Drilling-Fracturing in Shale Formations

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