Experimental study on fracture initiation and propagation in shale using supercritical carbon dioxide fracturing

Zhang, Xinwei; Lu, Yiyu; Tang, Jiren; Zhou, Zhe; Liao, Yang

doi:10.1016/j.fuel.2016.10.120

Cited by 397 publications

(170 citation statements)

References 30 publications

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“…The studies by Fan and Zhang [24] and Cheng et al [25] indicated that both geological and engineering parameters determine whether hydraulic fractures cross the natural fractures. Zhang et al [26] analyzed the different fracture geometry features induced by water and SC/L-CO 2 on cubic shale specimens. Zhou et al [27] indicated that the expansion and thermal stresses due to SC-CO 2 phase change can extend the fractures.…”

Section: Introductionmentioning

confidence: 99%

Hydraulic Fracturing Behavior in Shale with Water and Supercritical CO₂ under Triaxial Compression

Zhang

Yin

et al. 2020

Geofluids

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Comparing to the water fracturing fluid regularly used in the hydraulic fracturing operation, supercritical CO 2 (SC-CO 2 ) as a promising nonaqueous fracturing fluid has the great potential for the improvement of production and protection of shale reservoir. This paper presents an experimental study of the mechanical response and fracture propagation of shale fractured using water and SC-CO 2 under the different stress status and injection rate. According to the experimental results, SC-CO 2 fracturing is more time-consuming due to its compressibility which takes about 20 times more time than hydraulic fracturing using water under the same preset conditions. The breakdown pressure of shale can be affected by not only the anisotropy of itself but also the external factors like injection rate and deviator stress. Similar tendency of the breakdown pressure with the variation of bedding orientation can be observed in both of the fracturing using water and SC-CO 2 . However, all of the shale specimens fractured using SC-CO 2 show smaller breakdown pressure if compared with the shale specimens fractured using water. According to the results of fracture width evolution monitored by circumference during the fracturing, the fracture propping and proper size of the proppant are really important for the hydraulic fracturing.

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Section: Introductionmentioning

confidence: 99%

Hydraulic Fracturing Behavior in Shale with Water and Supercritical CO₂ under Triaxial Compression

Zhang

Yin

et al. 2020

Geofluids

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“…In recent years, SC-CO 2 fluid, which has many advantages for improving the rates of penetration and single well recovery, has been applied in the field of drilling and completion engineering, especially for the exploitation of unconventional reservoirs [7][8][9][10]. Moreover, it is reported that a SC-CO 2 jet has better rock erosion and fracturing capacity than a water jet does, thus, it has been widely considered as a promising and novel jet technology [11][12][13][14]. Besides, inside a reservoir bed, the dissolution of organic deposition by the seepage of SC-CO 2 can increase the permeability of the reservoirs, and the absorbed natural gas can be displaced through competitive adsorption with SC-CO 2 [15,16].…”

Section: Introductionmentioning

confidence: 99%

Effects of a Nano-Silica Additive on the Rock Erosion Characteristics of a SC-CO2 Jet under Various Operating Conditions

et al. 2017

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Abstract:In order to improve the erosion capacity of a supercritical carbon dioxide (SC-CO 2 ) jet, the influence of a nano-silica additive on the rock erosion characteristics was experimentally investigated. By impinging the SC-CO 2 jets with nano-silica mass fractions of 0 wt % (pure SC-CO 2 jet), 3 wt %, 6 wt %, 9 wt %, 12 wt %, 15 wt %, and 18 wt % on specimens of red sandstone, the erosion volumes under various operating conditions were measured and analyzed. Results show that an appropriate amount of nano-silica additive can greatly enhance the erosion ability of a SC-CO 2 jet. The effect on the erosion ability largely depends on the operating conditions. For instance, when the other conditions are fixed, 6 wt %, 9 wt %, 12 wt %, and 15 wt % were the optimum mass fractions, successively, with the inlet pressure increasing from 30 MPa to 60 MPa. With the increase in ambient pressure, the optimum mass fraction is unchanged under the constant inlet pressure, while it increases under the constant pressure drop. Additionally, the optimum mass fraction decreases when the fluid temperature increases. In addition, the optimal standoff distances are about five times the nozzle diameter of the nano-silica SC-CO 2 jet, and three times for the pure jet. This research provides a new method for effectively enhancing the rock erosion performance of a SC-CO 2 jet.

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“…The 3-D box-counting dimension (BCD) calculations can accurately reflect crack evolution law in the shale. The results indicate that the cracks have a more complex pattern and rough surface at an orientation of 90 • , due to crossed secondary cracks and shear failure.Various experimental methods, e.g., electromagnetic radiation (EMR), acoustic emission (AE), micro-seismic (MS), infrared technique, high speed digital imaging, and computerized tomography (CT), have been used to analyze the mechanical behavior of rocks (including shale) during uniaxial or triaxial loading [15][16][17][18][19][20][21]. CT scanning has been widely applied in the investigation of damage propagation since 1997, due to the three-dimensional (3-D) visualization and high-resolution imaging [22][23][24][25][26][27][28].…”

mentioning

confidence: 99%

Mechanical Property Measurements and Fracture Propagation Analysis of Longmaxi Shale by Micro-CT Uniaxial Compression

et al. 2018

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The mechanical properties and fracture propagation of Longmaxi shale loading under uniaxial compression were measured using eight cylindrical shale specimens (4 mm in diameter and 8 mm in height), with the bedding plane oriented at 0 • and 90 • to the axial loading direction, respectively, by micro computed tomography (micro-CT). Based on the reconstructed three-dimensional (3-D) CT images of cracks, different stages of the crack growth process in the 0 • and 90 • orientation specimen were revealed. The initial crack generally occurred at relatively smaller loading force in the 0 • bedding direction specimen, mainly in the form of tensile splitting along weak bedding planes. Shear sliding fractures were dominant in the specimens oriented at 90 • , with a small number of parallel cracks occurring on the bedding plane. The average thickness and volume of cracks in the 90 • specimen is higher than those for the specimen oriented at 0 • . The geometrical characterization of fractures segmented from CT scan binary images shows that a specific surface area correlates with tortuosity at the different load stages of each specimen. The 3-D box-counting dimension (BCD) calculations can accurately reflect crack evolution law in the shale. The results indicate that the cracks have a more complex pattern and rough surface at an orientation of 90 • , due to crossed secondary cracks and shear failure.Various experimental methods, e.g., electromagnetic radiation (EMR), acoustic emission (AE), micro-seismic (MS), infrared technique, high speed digital imaging, and computerized tomography (CT), have been used to analyze the mechanical behavior of rocks (including shale) during uniaxial or triaxial loading [15][16][17][18][19][20][21]. CT scanning has been widely applied in the investigation of damage propagation since 1997, due to the three-dimensional (3-D) visualization and high-resolution imaging [22][23][24][25][26][27][28]. Kawakata et al. used CT to study the initial mesoscopic damage characteristics of rock materials, and observed spatial fault development in granite undergoing compression [29,30]. In the experiment, only the damaged specimens, rather than the entire process from crack initiation to specimen destruction, were scanned, and then observed by 3-D reconstruction of X-ray CT images. To examine the entire process, Ge et al. investigated rock compression with a real-time CT test [23]. Through the use of the industrial CT images, the rock meso-damage propagation law was revealed. Rock failure started with micro-pore and micro-crack compression, growth, bifurcation, and development, followed by fracture. Sun et al. displayed real-time deformation in backfill body under loading using industrial CT in several slices, and provided insights into the process of faulting [31]. However, the relatively low spatial resolution and image quality of conventional industrial CT is not suitable for fine-grained rocks. Furthermore, the 3-D information was not fully captured or used, which limited the accuracy of further calculation ...

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Experimental study on fracture initiation and propagation in shale using supercritical carbon dioxide fracturing

Cited by 397 publications

References 30 publications

Hydraulic Fracturing Behavior in Shale with Water and Supercritical CO₂ under Triaxial Compression

Hydraulic Fracturing Behavior in Shale with Water and Supercritical CO₂ under Triaxial Compression

Effects of a Nano-Silica Additive on the Rock Erosion Characteristics of a SC-CO2 Jet under Various Operating Conditions

Mechanical Property Measurements and Fracture Propagation Analysis of Longmaxi Shale by Micro-CT Uniaxial Compression

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Experimental study on fracture initiation and propagation in shale using supercritical carbon dioxide fracturing

Cited by 397 publications

References 30 publications

Hydraulic Fracturing Behavior in Shale with Water and Supercritical CO2 under Triaxial Compression

Hydraulic Fracturing Behavior in Shale with Water and Supercritical CO2 under Triaxial Compression

Effects of a Nano-Silica Additive on the Rock Erosion Characteristics of a SC-CO2 Jet under Various Operating Conditions

Mechanical Property Measurements and Fracture Propagation Analysis of Longmaxi Shale by Micro-CT Uniaxial Compression

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Hydraulic Fracturing Behavior in Shale with Water and Supercritical CO₂ under Triaxial Compression

Hydraulic Fracturing Behavior in Shale with Water and Supercritical CO₂ under Triaxial Compression