Numerical simulation on spatial steering rule of directional perforation hydraulic fractures in low-permeability reservoir

Lu, Weiyong; Bai, Erhu; Le, Wei; He, Changchun; Sun, Yaohui; Shi, Lei

doi:10.3389/feart.2022.1007218

Cited by 4 publications

(2 citation statements)

References 44 publications

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“…The fractures produced via conventional hydraulic fracturing generally expand along the direction of the maximum horizontal principal stress, − and the direction of the fractures is singular. In the case of a preset fracture, hydraulic fracturing can further expand the length of the fracture extension and increase the influence range of the fracturing.…”

Section: Resultsmentioning

confidence: 99%

Mechanism and Practice of Multifracturing Using Dynamic Loads in a Low-Permeability Coal Reservoir

Tian

Cao

et al. 2023

ACS Omega

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The geological conditions of coal reservoirs in China are complex, and the reservoir permeability is generally lower. Multifracturing is an effective method of improving reservoir permeability and coalbed methane (CBM) production. In this study, two types of dynamic loads, CO 2 blasting and a pulse fracturing gun (PF-GUN), were used to conduct multifracturing engineering tests in nine surface CBM wells in the Lu'an mining area in the central and eastern parts of the Qinshui Basin. The curves of pressure versus time of the two dynamic loads were obtained in the laboratory. The prepeak pressurization time of the PF-GUN was 200 ms, and that of the CO 2 blasting was 2.05 ms, which just falls in the optimum pressurization time of multifracturing. The microseismic monitoring results revealed that, in terms of the fracture morphology, both the CO 2 blasting and PF-GUN loads produced multiple sets of fractures in the near-well zone. In the six wells used for the CO 2 blasting tests, an average of three branch fractures were produced outside of the main fracture, and the average angle between the main fracture and the branch fractures exceeded 60°. In the three wells stimulated by PF-GUN, an average of two branch fractures were produced outside of the main fracture, and the average angle between the main fracture and the branch fractures was 25−35°. The multifracture characteristics of the fractures formed via CO 2 blasting were more obvious. However, a coal seam is a multifracture reservoir with a large filtration coefficient; the fracture will not extend after reaching the maximum scale under a certain gas displacement condition. Compared with the traditional hydraulic fracturing technique, the nine wells used in the multifracturing tests exhibited an obvious stimulation effect with an average increase of 51.4% in daily production. The results of this study provide an important technical reference for the efficient development of CBM in low-and ultralowpermeability reservoirs.

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Section: Resultsmentioning

confidence: 99%

Mechanism and Practice of Multifracturing Using Dynamic Loads in a Low-Permeability Coal Reservoir

Tian

Cao

et al. 2023

ACS Omega

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“…Considering that horizontal Wells are the main factors affecting the formation of hydraulic fracture propagation around the wellbore, Lu et al 32 continued to use RFPA 2D -Flow to study the effects of different perforation densities and stresses on fracture initiation and propagation. The spatial morphology of complex fractures caused by perforation density and horizontal stress difference is found.…”

Section: Introductionmentioning

confidence: 99%

Prevention and Control of Coal and Gas Outburst by Directional Hydraulic Fracturing through Seams and Its Application

Li,

Zhou,

Hao

et al. 2023

ACS Omega

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The regionalized pressure relief, permeability enhancement, and outburst prevention of "three high and one low" coal seams with high gas, high ground stress, high outburst risk, and low permeability have become important problems to be solved urgently in realizing the sustainable development of coal mines. In this study, a combination of theoretical research, RFPA 2D -Flow numerical simulation, and field test was used to study the initiation mechanism and propagation law of directional hydraulic fracturing fractures through the seam. The results show that fracture initiation depends on the axial and radial horizontal stress of the fracture hole, the physical and mechanical properties of coal and rock, and the inside of the weakest layer. Single-hole hydraulic fracturing can achieve a pressure relief radius of 7−8 m, but there is a stress concentration zone outside, which is not conducive to regional pressure relief and permeability enhancement. Directional hydraulic fracturing with multiple holes produces an approximate cylindrical compression and crushing ring and a penetrating fracture surface along the center line of the pressure crack hole and the directional hole, which better eliminates the phenomenon of stress concentration in nondirectional hydraulic fracturing. The technology was applied to the 2238 auxiliary roadway of Chengzhuang Mine of Jinmei Group, and the field implementation results showed that field implementation results showed that directional hydraulic fracturing through the seam reduced the gas content in the coal seam to a great extent, and the coal seam gas content was reduced by about 42.3%, indicating that the technology can effectively reduce the risk of coal and gas outbursts.

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The hydraulic fracture propagation pattern induced by multi-stage temporary plugging and diverting fracturing in reservoirs with various lithologies: An experimental investigation

Zhou,

Zhang,

Zhang

et al. 2024

Physics of Fluids

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Multi-stage temporary plugging and diverting fracturing (TPDF) is an effective method for generating hydraulic fracture (HF) networks. This study investigates various lithological reservoirs in the Xinjiang region, obtaining downhole full-diameter cores for experimental analysis using true triaxial TPDF. The characteristics of HF morphology are quantitatively assessed by employing computed tomography (CT) scanning. The findings are summarized as follows: (1) Initial hydraulic fracturing of specimens with different lithologies results in σH-direction double-wing HF, while the first TPDF generates a single-wing HF along the σh direction, and the second TPDF produces a single-wing HF along the σH direction. (2) The volume and area of HFs in the first TPDF of volcanic rock increased by over 30%. The first TPDF effect is more pronounced in conglomerate rock, with HF volume over 25% and surface area increasing by more than 35%. (3) During multi-stage TPDF, volcanic rock transitions from initial HF to the formation of new HF, sandstone diverts from the wellbore to create new HF, and conglomerate generates new HF through multi-point initiation in the wellbore and HF. Each TPDF process involves the propagation of existing HFs and the generation of new ones. (4) The breakdown pressure in multi-stage TPDF increased by 46.5% and 51.6% in volcanic rock, while in sandstone, the first TPDF increased by 90.6%. In conglomerate rock, multi-stage TPDF saw increases of 51.2% and 41.9%, respectively. These findings offer theoretical insights for optimizing TPDF design in diverse lithological reservoirs.

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Numerical simulation on spatial steering rule of directional perforation hydraulic fractures in low-permeability reservoir

Cited by 4 publications

References 44 publications

Mechanism and Practice of Multifracturing Using Dynamic Loads in a Low-Permeability Coal Reservoir

Mechanism and Practice of Multifracturing Using Dynamic Loads in a Low-Permeability Coal Reservoir

Prevention and Control of Coal and Gas Outburst by Directional Hydraulic Fracturing through Seams and Its Application

The hydraulic fracture propagation pattern induced by multi-stage temporary plugging and diverting fracturing in reservoirs with various lithologies: An experimental investigation

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