Analysis of the Influence of a Natural Fracture Network on Hydraulic Fracture Propagation in Carbonate Formations

2013 ◽  
Vol 47 (2) ◽  
pp. 575-587 ◽  
Author(s):  
Zhiyuan Liu ◽  
Mian Chen ◽  
Guangqing Zhang
Keyword(s):  
Hydraulic Fracture ◽  
Fracture Propagation ◽  
Fracture Network ◽  
Natural Fracture ◽  
Hydraulic Fracture Propagation ◽  
Carbonate Formations

scholarly journals Numerical Simulation of Hydraulic Fracture Propagation in Coal Seams with Discontinuous Natural Fracture Networks

Processes ◽  
2018 ◽  
Vol 6 (8) ◽  
pp. 113 ◽  
Author(s):  
Shen Wang ◽  
Huamin Li ◽  
Dongyin Li
Keyword(s):  
Hydraulic Fracture ◽  
Fracture Propagation ◽  
Fracture Network ◽  
Natural Fracture ◽  
Cohesive Element ◽  
Natural Fractures ◽  
Fracture Networks ◽  
Coal Seams ◽  
Hydraulic Fracture Network ◽  
Hydraulic Fracture Propagation

To investigate the mechanism of hydraulic fracture propagation in coal seams with discontinuous natural fractures, an innovative finite element meshing scheme for modeling hydraulic fracturing was proposed. Hydraulic fracture propagation and interaction with discontinuous natural fracture networks in coal seams were modeled based on the cohesive element method. The hydraulic fracture network characteristics, the growth process of the secondary hydraulic fractures, the pore pressure distribution and the variation of bottomhole pressure were analyzed. The improved cohesive element method, which considers the leak-off and seepage behaviors of fracturing liquid, is capable of modeling hydraulic fracturing in naturally fractured formations. The results indicate that under high stress difference conditions, the hydraulic fracture network is spindle-shaped, and shows a multi-level branch structure. The ratio of secondary fracture total length to main fracture total length was 2.11~3.62, suggesting that the secondary fractures are an important part of the hydraulic fracture network in coal seams. In deep coal seams, the break pressure of discontinuous natural fractures mainly depends on the in-situ stress field and the direction of natural fractures. The mechanism of hydraulic fracture propagation in deep coal seams is significantly different from that in hard and tight rock layers.

Numerical model on predicting hydraulic fracture propagation in low-permeability sandstone

2020 ◽  
pp. 105678952096320
Author(s):  
Ji Shi ◽  
Jianhua Zhang ◽  
Chunyang Zhang ◽  
Tingting Jiang ◽  
Gang Huang
Keyword(s):  
Hydraulic Fracture ◽  
Fracture Propagation ◽  
Fracture Network ◽  
Natural Fracture ◽  
Low Permeability ◽  
Zone Method ◽  
Crustal Stress ◽  
Complex Fracture ◽  
Complex Fracture Network ◽  
Hydraulic Fracture Propagation

Hydraulic fracture propagation is hard to predict due to natural joints and crustal stress. This process may lead to uncontrollable changes in hydrogeological conditions. Therefore, prediction and control of fracture propagation are paramount to permeability increase in ore-bearing reservoir. The coupled fluid-solid model was utilized to predict the hydraulic fracture propagation in low-permeability sandstone of a uranium mine. For this study, the model was modified to allow fractures to propagate randomly by using the cohesive zone method. The simulation was developed on a three-step process. First, geological data required to run the model, including crustal stress, strength and permeability, were assembled. Next, fracture propagation under different conditions of stress and injection volume were simulated. In the final step, experimental data required to validate the model were obtained. The simulation results indicate that the principal stress, distribution and orientation of natural fracture have vital influence on fracture propagation and induced complex fracture network. This work provides a theoretical basis for the application of hydraulic fracture in low-permeability sandstone reservoir and ensures the possibility to predict the generation of complex fracture network.

scholarly journals Study of Interactions between Induced and Natural Fracture Effects on Hydraulic Fracture Propagation Using a Discrete Approach

Lithosphere ◽  
2021 ◽  
Vol 2021 (Special 4) ◽  
Author(s):  
Yulong Zhang ◽  
Bei Han ◽  
Xin Zhang ◽  
Yun Jia ◽  
Chun Zhu
Keyword(s):  
Hydraulic Fracture ◽  
Fracture Propagation ◽  
Flow Simulation ◽  
Injection Pressure ◽  
Natural Fracture ◽  
Uniaxial Compression Test ◽  
Differential Stress ◽  
Rock Samples ◽  
Approach Angle ◽  
Hydraulic Fracture Propagation

Abstract The interaction mode of induced fracture and natural fracture plays an important role in prediction of hydraulic fracture propagation. In this paper, a two-dimensional hydromechanical coupled discrete element model is first introduced in the framework of particle flow simulation, which can well take into account mechanical and hydraulic properties of rock samples with natural fracture. The model’s parameters are strictly calibrated by conducting numerical simulations of uniaxial compression test and direct tensile and shear tests, as well as fluid flow test. The effectiveness of coupled model is also assessed by describing hydraulic fracture propagation in two representative cases, respectively, rock samples with and without preexisting fracture. With this model in hand, the effects of interaction between induced and natural fractures with different approach angles and differential stresses on fluid injection pressure and fracture propagation patterns are investigated and discussed. Results suggest that the interaction modes mainly involve three basic behaviors including the arrested, captured with offset, and directly crossing. For a given differential stress, the captured offset of hydraulic fracture by natural fracture gradually decreases with the approach angle increase, while for a fixed approach angle, that captured offset increases with differential stress decrease.

scholarly journals Numerical Investigation of Hydraulic Fracture Propagation Based on Cohesive Zone Model in Naturally Fractured Formations

Processes ◽  
2019 ◽  
Vol 7 (1) ◽  
pp. 28 ◽  
Author(s):  
Jianxiong Li ◽  
Shiming Dong ◽  
Wen Hua ◽  
Xiaolong Li ◽  
Xin Pan
Keyword(s):  
Hydraulic Fracturing ◽  
Hydraulic Fracture ◽  
Cohesive Zone ◽  
Coupled Model ◽  
Fracture Propagation ◽  
Fracture Network ◽  
Zone Model ◽  
Naturally Fractured ◽  
Hydraulic Fracture Propagation ◽  
Multiple Cluster

Complex propagation patterns of hydraulic fractures often play important roles in naturally fractured formations due to complex mechanisms. Therefore, understanding propagation patterns and the geometry of fractures is essential for hydraulic fracturing design. In this work, a seepage–stress–damage coupled model based on the finite pore pressure cohesive zone (PPCZ) method was developed to investigate hydraulic fracture propagation behavior in a naturally fractured reservoir. Compared with the traditional finite element method, the coupled model with global insertion cohesive elements realizes arbitrary propagation of fluid-driven fractures. Numerical simulations of multiple-cluster hydraulic fracturing were carried out to investigate the sensitivities of a multitude of parameters. The results reveal that stress interference from multiple-clusters is responsible for serious suppression and diversion of the fracture network. A lower stress difference benefits the fracture network and helps open natural fractures. By comparing the mechanism of fluid injection, the maximal fracture network can be achieved with various injection rates and viscosities at different fracturing stages. Cluster parameters, including the number of clusters and their spacing, were optimal, satisfying the requirement of creating a large fracture network. These results offer new insights into the propagation pattern of fluid driven fractures and should act as a guide for multiple-cluster hydraulic fracturing, which can help increase the hydraulic fracture volume in naturally fractured reservoirs.

scholarly journals Numerical simulation of horizontal well network fracturing in glutenite reservoir

2018 ◽  
Vol 73 ◽  
pp. 53
Author(s):  
Minhui Qi ◽  
Mingzhong Li ◽  
Yanchao Li ◽  
Tiankui Guo ◽  
Song Gao
Keyword(s):  
Numerical Simulation ◽  
Hydraulic Fracturing ◽  
Hydraulic Fracture ◽  
Horizontal Well ◽  
Fracture Propagation ◽  
Simulation Method ◽  
Fracture Network ◽  
Fluid Viscosity ◽  
Coupled Flow ◽  
Hydraulic Fracture Propagation

Hydraulic fracturing is an economically effective technology developing the glutenite reservoirs, which have far stronger heterogeneity than the conventional sandstone reservoir. According to the field production experience of Shengli Oilfield, horizontal-well fracturing is more likely to develop a complex fractured network, which improves the stimulated volume of reservoir effectively. But the clear mechanism of horizontal-well hydraulic fracture propagation in the glutenite reservoirs is still not obtained, thus it is difficult to effectively carry out the design of fracturing plan. Based on the characteristics of the glutenite reservoirs, a coupled Flow-Stress-Damage (FSD) model of hydraulic fracture propagation is established. The numerical simulation of fracturing expansion in the horizontal well of the glutenite reservoir is conducted. It is shown that a square mesh-like fracture network is developed near the horizontal well in the reservoir with lower stress difference, in which fracture is more prone to propagate along the direction of the minimum principal stress as well. High fracturing fluids injection displacement and high fracturing fluid viscosity lead to the rise of static pressure of the fracture, which results in the rise of fracture complexity, and greater probability to deflect when encountering gravels. As the perforation density increases, the micro-fractures generated at each perforation gather together faster, and the range of the stimulated reservoir is also relatively large. For reservoirs with high gravel content, the complexity of fracture network and the effect of fracture communication are obviously increased, and the range of fracture deflection is relatively large. In the case of the same gravel distribution, the higher the tensile strength of the gravel, the greater fracture tortuosity and diversion was observed. In this paper, a simulation method of horizontal well fracture network propagation in the reservoirs is introduced, and the result provides the theoretical support for fracture network morphology prediction and plan design of hydraulic fracturing in the glutenite reservoir.

scholarly journals Numerical Simulation of the Influence of Natural Fractures on Hydraulic Fracture Propagation

Geofluids ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-12 ◽  
Author(s):  
Song Yaobin ◽  
Lu Weiyong ◽  
He Changchun ◽  
Bai Erhu
Keyword(s):  
Tensile Strength ◽  
Principal Stress ◽  
Hydraulic Fracture ◽  
Fracture Propagation ◽  
Natural Fracture ◽  
Hydraulic Fractures ◽  
Stress Difference ◽  
Natural Fractures ◽  
Approach Angle ◽  
Hydraulic Fracture Propagation

According to the theory of plane mechanics involving the interaction of hydraulic and natural fractures, the law of hydraulic fracture propagation under the influence of natural fractures is verified using theoretical analysis and RFPA2D-Flow numerical simulation approaches. The shear and tensile failure mechanisms of rock are simultaneously considered. Furthermore, the effects of the approach angle, principal stress difference, tensile strength and length of the natural fracture, and elastic modulus and Poisson’s ratio of the reservoir on the propagation law of a hydraulic fracture are investigated. The following results are obtained: (1) The numerical results agree with the experimental data, indicating that the RFPA2D-Flow software can be used to examine the hydraulic fracture propagation process under the action of natural fractures. (2) In the case of a low principal stress difference and low approach angle, the hydraulic fracture likely causes shear failure along the tip of the natural fracture. However, under a high stress difference and high approach angle, the hydraulic fracture spreads directly through the natural fracture along the original direction. (3) When natural fractures with a low tensile strength encounter hydraulic fractures, the hydraulic fractures likely deviate and expand along the natural fractures. However, in the case of natural fractures with a high tensile strength, the natural fracture surface is closed, and the hydraulic fracture directly passes through the natural fracture, propagating along the direction of the maximum principal stress. (4) Under the same principal stress difference, a longer natural fracture corresponds to the easier initiation and expansion of a hydraulic fracture from the tip of the natural fracture. However, when the size of the natural fracture is small, the hydraulic fracture tends to propagate directly through the natural fracture. (5) A smaller elastic modulus and larger Poisson’s ratio of the reservoir result in a larger fracture initiation pressure. The presented findings can provide theoretical guidance regarding the hydraulic fracturing of reservoirs with natural fractures.

scholarly journals Analysis of Hydraulic Fracture Propagation Using a Mixed Mode and a Uniaxial Strain Model considering Geomechanical Properties in a Naturally Fractured Shale Reservoir

Geofluids ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-14
Author(s):  
Youngho Jang ◽  
Gayoung Park ◽  
Seoyoon Kwon ◽  
Baehyun Min
Keyword(s):  
Shale Gas ◽  
Hydraulic Fracture ◽  
Mixed Mode ◽  
Fracture Propagation ◽  
Fracture Network ◽  
Uniaxial Strain ◽  
Propagation Model ◽  
Geomechanical Properties ◽  
Hydraulic Fracture Propagation ◽  
Strain Model

This study proposes a hydraulic fracture propagation model with a mixed mode comprising opening and sliding modes to describe a complex fracture network in a naturally fractured shale gas formation. We combine the fracture propagation model with the mixed mode and the uniaxial strain model with tectonic impacts to calculate the stress distribution using geomechanical properties. A discrete fracture network is employed to realize the fracture network composed of natural and hydraulic fractures. We compare the fracture propagation behaviours of three cases representing the Barnett, Marcellus, and Eagle Ford shale gas formations. Sensitivity analysis is performed to investigate the effects of the geomechanical properties of the reservoir on the sliding mode’s contribution to the mixed mode. The numerical results highlight the significance of the mixed mode for the accurate assessment of fracture propagation behaviours in shale gas formations with high brittleness.

Sign in / Sign up

Export Citation Format

Share Document