A New Approach for Numerical Modeling of Hydraulic Fracture Propagation in Naturally Fractured Reservoirs

Keshavarzi, Reza; Mohammadi, Soheil

doi:10.2118/152509-ms

Cited by 44 publications

(22 citation statements)

References 21 publications

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“…Taleghani et al [80] used XFEM to investigate the hydraulic fracture intersecting a single natural fracture [48]; implemented it on the effects of intersection angles between hydraulic fractures and natural fractures. However, there are still many tough bones for this method, such as the branching and intersection of fractures, fluid flow related to fractures, and the heterogeneities of rocks that may bring solution problem, etc.…”

Section: Numerical Methods For Hydraulic Fracturing Modelingmentioning

confidence: 99%

A review on hydraulic fracturing of unconventional reservoir

et al. 2015

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a b s t r a c tHydraulic fracturing is widely accepted and applied to improve the gas recovery in unconventional reservoirs. Unconventional reservoirs to be addressed here are with very low permeability, complicated geological settings and in-situ stress field etc. All of these make the hydraulic fracturing process a challenging task. In order to effectively and economically recover gas from such reservoirs, the initiation and propagation of hydraulic fracturing in the heterogeneous fractured/ porous media under such complicated conditions should be mastered. In this paper, some issues related to hydraulic fracturing have been reviewed, including the experimental study, field study and numerical simulation. Finally the existing problems that need to be solved on the subject of hydraulic fracturing have been proposed.Unconventional gas mainly includes shale gas, tight gas and coal seam gas. Shale gas is commonly in mudstone, shale and between them the interlayers of sandstone. Tight gas often has been stored in tight sandstone or sometimes limestone. Coal bed methane is contained within coal seams. Their common attribute is that the permeability of the matrix is very low, and the permeability often has been improved by artificial or natural fractures [55]. However, the differences between them are also significant. For example, the effective shale thickness for gas production should be more than 15 m while the height of coal is generally from 0.6 m to 5.0 m [68], as coal seams to be fractured may be multiple and thin, hydraulic fracturing in coal needs to be more accurately designed and controlled. Moreover, the Young's modulus of coal is smaller than shale and tight sandstone, the permeability of coal is more sensitive to stress due to the development of cleat system, and leakoff in coal may be more severe, which can significantly affect the fracturing result. Due to the complexity of unconventional reservoirs, it is challenging to predict the initiation and propagation of hydraulic fractures [39]. For example, the complex in situ stress state and distribution of rocks of varied attributes, which may change the profile of hydraulic fractures [38]; the existence of arbitrary pre-existing interfaces may diversify or arrest hydraulic fractures [93]; the temperature effect [75]; the fluid loss and transport of proppant; the competition between hydraulic fractures, and its recession and closure [4]. Thus, it is crucial to explore how hydraulic fracturing process will happen in complex geological settings.Firsthand materials of hydraulic fracturing come from in-door experiments, and field study. Laboratory study undergoes from small-scale rock samples with several cubic centimetres to large ones with one cubic metre or more. Since it is easy to control the stress conditions and make artificial structures within samples, hydraulic fracturing process with different stress field and rock structures can be conveniently studied. Especially in large scale experiments, it is possible to build a full size borehole, or to contr...

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Section: Numerical Methods For Hydraulic Fracturing Modelingmentioning

confidence: 99%

A review on hydraulic fracturing of unconventional reservoir

et al. 2015

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“…Newton's numerical method is used to solve the system of nonlinear equations. Picard coupling (Li 1991;Adachi et al 2007) is used to couple the fracture mechanics and fluid flow at every updated timestep. If the convergence criterion is not satisfied, the net pressure is modified at each iteration step as…”

Section: Iterative Algorithmmentioning

confidence: 99%

Simultaneous Multifracture Treatments: Fully Coupled Fluid Flow and Fracture Mechanics for Horizontal Wells

2014

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Successfully creating multiple hydraulic fractures in horizontal wells is critical for unconventional gas production economically. Optimizing the stimulation of these wells will require models that can account for the simultaneous propagation of multiple, potentially nonplanar, fractures.In this paper, a novel fracture-propagation model (FPM) is described that can simulate multiple-hydraulic-fracture propagation from a horizontal wellbore. The model couples fracture deformation with fluid flow in the fractures and the horizontal wellbore. The displacement discontinuity method (DDM) is used to represent the mechanics of the fractures and their opening, including interaction effects between closely spaced fractures. Fluid flow in the fractures is determined by the lubrication theory. Frictional pressure drop in the wellbore and perforation zones is taken into account by applying Kirchoff's first and second laws. The fluid-flow rates and pressure compatibility are maintained between the wellbore and the multiple fractures with Newton's numerical method. The model generates physically realistic multiple-fracture geometries and nonplanar-fracture trajectories that are consistent with physical-laboratory results and inferences drawn from microseismic diagnostic interpretations.One can use the simulation results of the FPM for sensitivity analysis of in-situ and fracture treatment parameters for shale-gas stimulation design. They provide a physics-based complex fracture network that one can import into reservoir-simulation models for production analysis. Furthermore, the results from the model can highlight conditions under which restricted width occurs that could lead to proppant screenout.

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“…The problem of hydraulic and natural fracture interaction has been widely investigated both experimentally (Lamont 2 and Jessen, 1963;Athavale and Miskimins, 2008;Zhou and Xie, 2011) and numerically (Taleghani and Olson, 2009;Chuprakov et al, 2010;Keshavarzi and Mohammadi, 2012;, but in present paper, this problem will not be focused.…”

Section: Introductionmentioning

confidence: 99%