A new method for calculating the direction of fracture propagation by stress numerical search based on the displacement discontinuity method

Cong, Ziyuan; Li, Yuwei; Liu, Yu; Xiao, Yonghui

doi:10.1016/j.compgeo.2021.104482

Cited by 29 publications

(10 citation statements)

References 45 publications

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“…5. When the calculation error of P i and P i+1 is less than the convergence accuracy δ (δ = 0.001 MPa), the fracture propagation angle is calculated by the stress numerical search method (SNSM) (Cong et al, 2021), and a displacement discontinuous element is added in this direction (n is the convergence coefficient; in this article, n = 0.2). If the added unit meets the NF in the calculation domain, the interactive propagation is judged by the propagation criterion in Section 2.4.…”

Section: Numerical Methods For the Modelmentioning

confidence: 99%

Simulation Study on Interactive Propagation of Hydraulic Fractures and Natural Fractures in Shale Oil Reservoir

et al. 2022

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Natural fractures are developed in the shale oil reservoir, and the hydraulic fracture (HF) morphology is complex. The fracture shape can be inverted by using fracture propagation numerical simulation technology, which provides guidance for fracturing parameter design and fracturing process optimization. However, the existing models still have many deficiencies in the interactive propagation mechanism of HF and natural fracture (NF). Based on the three interactive modes of HF and NF (HF propagation without NF, HF propagation with full NF, and HF propagation with half NF), this work establishes the fracture propagation model and puts forward the simulation calculation method. The Brinkman equation is used to modify the leakage model based on Darcy’s law, and G1701H well is taken as an example to simulate the fracture propagation law under different interaction modes. The research shows that there is a transition region between the HF wall and rock matrix. The greater the porosity and permeability of the rock matrix, the more significant the influence of the transition region on leakage. The NF zone will change the propagation direction of the main fracture. When there are multiple clusters of fractures in the same fracturing section, only some HFs meet with natural fractures, and it is easy to form a “T”-shaped fracture network. The results improve the existing hydraulic fracturing model and provide help for fracturing parameter design and fracture parameter inversion of the shale oil reservoir.

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Section: Numerical Methods For the Modelmentioning

confidence: 99%

Simulation Study on Interactive Propagation of Hydraulic Fractures and Natural Fractures in Shale Oil Reservoir

et al. 2022

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“…In recent decades, a series of numerical simulation calculation methods such as finite element method, boundary element method, discrete element method, meshless method and finite difference method have appeared [10]. Cheng et al used the finite element method to deal with the elastic and flow equations, studied the problem of multi-layer hydraulic crack propagation in a plane homogeneous longitudinal direction, and proposed a finite element solution for plane arbitrarily shaped cracks perpendicular to the interface of multi-layer media [11][12][13]. However, this method has limitations in simulating the crack intersection and non-planar propagation.…”

Section: Introductionmentioning

confidence: 99%

Simulation of Key Influencing Factors of Hydraulic Fracturing Fracture Propagation in a Shale Reservoir Based on the Displacement Discontinuity Method (DDM)

Ma,

Tang

2024

Processes

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In the process of the large-scale hydraulic fracturing of a shale gas field in the Weiyuan area of Sichuan province, the quantitative description and evaluation of hydraulic fracture expansion morphology and the three-dimensional distribution law are the key points of evaluation of block fracturing transformation effect. Many scholars have used the finite element method, discrete element method, grid-free method and other numerical simulation methods to quantitatively characterize hydraulic fractures, but there are often the problems that the indoor physical simulation results are much different from the actual results and the accuracy of most quantitative studies is poor. Considering rock mechanics parameters and based on the displacement discontinuity method (DDM), a single-stage multi-cluster fracture propagation model of horizontal well was established. The effects of Young’s modulus, Poisson’s ratio, the in situ stress difference, the approximation angle, the perforation cluster number and the perforation spacing on the formation of complex fracture networks and on the geometrical parameters of hydraulic fractures were simulated. The research results can provide theoretical reference and practical guidance for the optimization of large-scale fracturing parameters and the quantitative post-fracturing evaluation of horizontal wells in unconventional reservoirs such as shale gas reservoirs.

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“…The pre-CO2 process not only replenishes the formation energy but also affects the mechanical properties of reservoir rocks. Ignoring its influence will inevitably affect the numerical simulation results and cause significant errors, affect construction design, and cause engineering losses [26][27][28] .…”

Section: Introductionmentioning

confidence: 99%

A Prediction Method for the Initiation Pressure of Pre-CO 2 Fracturing Considering the Modification of Rock Mechanical Parameters after CO 2 Treatment

Kong,

Sun,

Wei

et al. 2024

Preprint

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The utilization of CO2 fracturing fluid presents a notable reduction in the challenges associated with reservoir opening, particularly in dense and unconventional reservoirs. The widespread adoption of this technique underscores its efficacy. The establishment of a more realistic CO2 fracturing model serves to elucidate the intricate mechanisms underlying CO2 fracturing transformation. Additionally, it furnishes a foundational framework for devising comprehensive fracturing construction plans. However, current research has neglected to consider the influence of CO2 on rock properties during CO2 fracturing, resulting in an inability to precisely replicate the alterations in the reservoir post-CO2 injection into the formation. This disparity from the actual conditions poses a substantial limitation to the application and advancement of CO2 fracturing technology. This work integrates the variations in physical parameters of rocks after complete contact and reaction with CO2 into the numerical model of crack propagation. This comprehensive approach fully acknowledges the impact of pre-CO2 exposure on the mechanical parameters of reservoir rocks. Consequently, it authentically restores the reservoir state following CO2 injection, ensuring a more accurate representation of the post-fracturing conditions. The research findings reveal that post-CO2 treatment, the elastic modulus of reservoir shale experiences a reduction of 12.5%, Poisson's ratio decreases by 11.8%, tensile strength decreases by 7.9%, permeability increased by 180%. Additionally, the pre-injection of CO2 into the reservoir induces a notable increase in pore pressure in the near wellbore zone. In comparison with conventional numerical simulation methods, the approach outlined in this paper yields a reduction in the error associated with predicting fracturing pressure by 9.8%. The model and methodology presented herein serve as a practical tool for accurately forecasting the initiation pressure of CO2 fracturing.

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A new method for calculating the direction of fracture propagation by stress numerical search based on the displacement discontinuity method

Cited by 29 publications

References 45 publications

Simulation Study on Interactive Propagation of Hydraulic Fractures and Natural Fractures in Shale Oil Reservoir

Simulation Study on Interactive Propagation of Hydraulic Fractures and Natural Fractures in Shale Oil Reservoir

Simulation of Key Influencing Factors of Hydraulic Fracturing Fracture Propagation in a Shale Reservoir Based on the Displacement Discontinuity Method (DDM)

A Prediction Method for the Initiation Pressure of Pre-CO 2 Fracturing Considering the Modification of Rock Mechanical Parameters after CO 2 Treatment

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