Hydraulic fracture initiation and propagation: roles of wellbore trajectory, perforation and stress regimes

Hossain, Mofazzal; Rahman, Motiur; Rahman, Sheik S.

doi:10.1016/s0920-4105(00)00056-5

Cited by 289 publications

(112 citation statements)

References 27 publications

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“…The following sections present a mathematical analysis of the two initiation locations. In order to simplify the analysis, in the mathematical model the coal and rock near borehole will be considered to be homogeneous elastic bodies [18][19][20][21]. In addition, the filtration effect of the layers and the changes in pore water pressure will not be taken into account in the modeling.…”

Section: Fracture Initiation Locationmentioning

confidence: 99%

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Determination of Fracture Initiation Locations during Cross-Measure Drilling for Hydraulic Fracturing of Coal Seams

Cheng

et al. 2016

Energies

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When drilling coal-bearing sequences to enhance coal seam permeability by hydraulic fracturing (HF), the location where fractures are initiated is important. To date, most research on fracture initiation has studied the problem in two dimensions. In this study, a three-dimensional model to assess initiation location is developed. The model analyzes the stress state of both the borehole wall and the coal-rock interface and the model shows that the fracture initiation location is affected by in situ stress, the dip of the coal seam, and the angle between the borehole and the coal seam. How the initiation location changes near different types of geological faults is calculated by assuming typical in situ stresses for the faults. Following these calculations, physical experiments were carried out to emulate cross-measure hydraulic fracturing under stress conditions equivalent to those in the Chongqing Tonghua coal mine, China. Fracture initiation during the experiments was monitored by an acoustic emission system. The experimental results were consistent with the theoretical calculations. This implies that the three-dimensional model for assessing the locations of fracture initiation can be applied to forecast the initiation location of fractures generated by cross-measure drilling. The assessment model provides reference values for this type of drilling in underground mines.

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Section: Fracture Initiation Locationmentioning

confidence: 99%

“…In general, any point at the borehole wall is considered to be in tensile failure [19,20]. Since the tensile strength of coal is less than that of rock, the maximum tangential stress σ θ reaches the tensile strength of coal first.…”

Section: Initiation Location In a Coal Seammentioning

confidence: 99%

Determination of Fracture Initiation Locations during Cross-Measure Drilling for Hydraulic Fracturing of Coal Seams

Cheng

et al. 2016

Energies

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“…In hydraulic fracturing process, the fracture starts to grow at an angular position, say θ, with the increase of borehole pressure p from zero to the threshold. The condition for borehole wall cracking initiation can be given by Hossain et al [21]:…”

Section: Model For Calculation Of Initial Cracking Parametersmentioning

confidence: 99%

“…Thus, the principle stresses in Equation (1) . For simplicity, the Poisson ratio can be assumed as zero [13,21].…”

Section: State Of In-situ Stress In Coal Seamsmentioning

confidence: 99%

Analysis on the Initial Cracking Parameters of Cross-Measure Hydraulic Fracture in Underground Coal Mines

Cheng

et al. 2015

Energies

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Initial cracking pressure and locations are important parameters in conducting cross-measure hydraulic fracturing to enhance coal seam permeability in underground coalmines, which are significantly influenced by in-situ stress and occurrence of coal seam. In this study, stress state around cross-measure fracturing boreholes was analyzed using in-situ stress coordinate transformation, then a mathematical model was developed to evaluate initial cracking parameters of borehole assuming the maximum tensile stress criterion. Subsequently, the influences of in-situ stress and occurrence of coal seams on initial cracking pressure and locations in underground coalmines were analyzed using the proposed model. Finally, the proposed model was verified with field test data. The results suggest that the initial cracking pressure increases with the depth cover and coal seam dip angle. However, it decreases with the increase in azimuth of major principle stress. The results also indicate that the initial cracking locations concentrated in the second and fourth quadrant in polar coordinate, and shifted direction to the strike of coal seam as coal seam dip angle and azimuth of maximum principle stress increase. Field investigation revealed consistent rule with the developed model that the initial cracking pressure increases with the coal seam dip angle. Therefore, the proposed

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“…It has become a research hotspot and difficulty in CBM hydraulic fracturing. Nowadays studies on initiation pressure of sandstone hydraulic fracturing are mainly based on mechanics of elasticity tensile failure criterion, and the relative calculation models are based on the premise of homogeneous formation [1][2][3][4][5]. For the fractured reservoir, Yan Jin [6,7] took the influence of reservoir fractures on initiation pressure of open hole well into consideration to establish the relative calculation model.…”

Section: Introductionmentioning

confidence: 99%

The Calculation Model of Initiation Pressure During Hydraulic Fracturing Process of Perforated Coal Seams

Li¹,

Ai²

2013

TOEFJ

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There are lots of cleats, fractures and many other structure weak planes in coal seams, which make the bullet holes and cleats intersecting. During the hydraulic fracturing process in coal seams, fractures will initiate at coal rock body of borehole wall, and cleats or fractures are different from conventional reservoirs. Thus a new model for initiation pressure calculation during coal seams fracturing should be established. Based on the rock mechanics and elasticity mechanics, and also on network distribution characteristics of coal seam cleats and the space position relationships between the intersected bullet holes and cleats, stress distribution around the bullet holes and at the cleats wall were deducted. The model was established in tensile failure condition. The calculated initiation fracture pressure of Well HX-3 was 10.71MPa. The pressure obtained from bottom hole pressure gauge was 11.24MPa. The relative error was 4.72%. The model could be applied for initiation pressure calculation during hydraulic fracturing process in coal seams. The fractures would initiate at the cleats during fracturing.

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Hydraulic fracture initiation and propagation: roles of wellbore trajectory, perforation and stress regimes

Cited by 289 publications

References 27 publications

Determination of Fracture Initiation Locations during Cross-Measure Drilling for Hydraulic Fracturing of Coal Seams

Determination of Fracture Initiation Locations during Cross-Measure Drilling for Hydraulic Fracturing of Coal Seams

Analysis on the Initial Cracking Parameters of Cross-Measure Hydraulic Fracture in Underground Coal Mines

The Calculation Model of Initiation Pressure During Hydraulic Fracturing Process of Perforated Coal Seams

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