scholarly journals Migration and Distribution Characteristics of Proppant at the Corner of Horizontal Fracture Network in Coal Seam

2021 ◽  
Vol 9 ◽  
Author(s):  
Qingying Cheng ◽  
Haoze Li ◽  
Bingxiang Huang ◽  
Xinglong Zhao ◽  
Zheng Sun ◽  
...  
Keyword(s):  
High Velocity ◽  
Fracture Network ◽  
Distribution Characteristics ◽  
Low Velocity ◽  
Complex Fracture ◽  
Main Fracture ◽  
Complex Fracture Network ◽  
The Impact ◽  
Migration Law ◽  
Free Area

A complex fracture network is composed of many similar structures. The migration law of proppant at each structure is the core and basic content of the migration law of proppant in complex fracture network, and there is little research. In this study, the EulerianEulerian method (TEM) is used to analyze the migration and distribution characteristics of solid–liquid two phases at the fracture corner according to different corner types of the fracture network. The results show that the migration characteristics of proppant in the corner area can be divided into the corner anomaly area, buffer area, and stability area; the influence of the turning angle on proppant migration is mainly concentrated at the corner and in the range of 4 times the fracture width after turning. The probability of sand plugging at the corner of the “Y → T” fracture is lower than that of “L → l”, higher than that of the “X → +” wing branch fracture, and lower than that of the main fracture. At the corner of the fracture network, after the solid flow turns, the proppant will form a high sand area on the side of the impact fracture surface, then rebound back to the fracture, form a sand-free area on the other side, and form a high-velocity core in the refraction interval. At the corner of the “L → l” fracture, there are one high sand area, one non-sand area, two low-velocity areas, and one high-velocity area; there are three low-velocity areas, two sand-free areas, and one high sand area at the corner of the “Y → T” fracture; at the corner of the “X → +” fracture, there is a high sand area and no sand-free area, and the flow velocity of the main fracture is much greater than that of the wing branch fracture.

Numerical Simulation of Complex Fracture Network Development by Hydraulic Fracturing in Naturally Fractured Ultratight Formations

2013 ◽  
Author(s):  
Hannes Hofmann ◽  
Tayfun Babadagli ◽  
Günter Zimmermann
Keyword(s):  
Fracture Network ◽  
Natural Fracture ◽  
Fracture Networks ◽  
Network Development ◽  
Complex Fracture ◽  
Fracture Patterns ◽  
Fracture Systems ◽  
Fracture Development ◽  
Complex Fracture Network ◽  
Treatment Designs

The creation of large complex fracture networks by hydraulic fracturing is imperative for enhanced oil recovery from tight sand or shale reservoirs, tight gas extraction, and Hot-Dry-Rock (HDR) geothermal systems to improve the contact area to the rock matrix. Although conventional fracturing treatments may result in bi-wing fractures, there is evidence by microseismic mapping that fracture networks can develop in many unconventional reservoirs, especially when natural fracture systems are present and the differences between the principle stresses are low. However, not much insight is gained about fracture development as well as fluid and proppant transport in naturally fractured tight formations. In order to clarify the relationship between rock and treatment parameters, and resulting fracture properties, numerical simulations were performed using a commercial Discrete Fracture Network (DFN) simulator. A comprehensive sensitivity analysis is presented to identify typical fracture network patterns resulting from massive water fracturing treatments in different geological conditions. It is shown how the treatment parameters influence the fracture development and what type of fracture patterns may result from different treatment designs. The focus of this study is on complex fracture network development in different natural fracture systems. Additionally, the applicability of the DFN simulator for modeling shale gas stimulation and HDR stimulation is critically discussed. The approach stated above gives an insight into the relationships between rock properties (specifically matrix properties and characteristics of natural fracture systems) and the properties of developed fracture networks. Various simulated scenarios show typical conditions under which different complex fracture patterns can develop and prescribe efficient treatment designs to generate these fracture systems. Hydraulic stimulation is essential for the production of oil, gas, or heat from ultratight formations like shales and basement rocks (mainly granite). If natural fracture systems are present, the fracturing process becomes more complex to simulate. Our simulation results reveal valuable information about main parameters influencing fracture network properties, major factors leading to complex fracture network development, and differences between HDR and shale gas/oil shale stimulations.

scholarly journals Performance-based fractal fracture model for complex fracture network simulation

2017 ◽  
Vol 15 (1) ◽  
pp. 126-134 ◽  
Author(s):  
Wen-Dong Wang ◽  
Yu-Liang Su ◽  
Qi Zhang ◽  
Gang Xiang ◽  
Shi-Ming Cui
Keyword(s):  
Network Simulation ◽  
Fracture Network ◽  
Fracture Model ◽  
Complex Fracture ◽  
Complex Fracture Network ◽  
Fractal Fracture

scholarly journals A New Approach for Automatic Optimization of Complex Fracture Network in Shale Reservoirs

Lithosphere ◽  
2021 ◽  
Vol 2021 (Special 1) ◽  
Author(s):  
Haibo Wang ◽  
Tong Zhou ◽  
Fengxia Li
Keyword(s):  
Shale Gas ◽  
Flow Model ◽  
Optimization Method ◽  
Fracture Network ◽  
Gas Reservoirs ◽  
Fracture Length ◽  
Complex Fracture ◽  
Shale Gas Reservoirs ◽  
Automatic Optimization ◽  
Complex Fracture Network

Abstract Shale gas reservoirs have gradually become the main source for oil and gas production. The automatic optimization technology of complex fracture network in fractured horizontal wells is the key technology to realize the efficient development of shale gas reservoirs. In this paper, based on the flow model of shale gas reservoirs, the porosity/permeability of the matrix system and natural fracture system is characterized. The fracture network morphology is finely characterized by the fracture network expansion calculation method, and the flow model was proposed and solved. On this basis, the influence of matrix permeability, matrix porosity, fracture permeability, fracture porosity, and fracture length on the production of shale gas reservoirs is studied. The optimal design of fracture length and fracture location was carried, and the automatic optimization method of complex fracture network parameters based on simultaneous perturbation stochastic approximation (SPSA) was proposed. The method was applied in a shale gas reservoir, and the results showed that the proposed automatic optimization method of the complex fracture network in shale gas reservoirs can automatically optimize the parameters such as fracture location and fracture length and obtain the optimal fracture network distribution matching with geological conditions.

scholarly journals Experimental and numerical analysis of high and low velocity impacts against neat and shear thickening fluid (STF) impregnated weave fabrics

2018 ◽  
Vol 183 ◽  
pp. 01044
Author(s):  
Djalel Eddine Tria ◽  
Larbi Hemmouche ◽  
Abdelhadi Allal ◽  
Abdelkader Benouali
Keyword(s):  
High Velocity ◽  
Shear Thickening ◽  
Force Sensor ◽  
Low Velocity Impact ◽  
Dynamic Force ◽  
Low Velocity ◽  
Shear Thickening Fluid ◽  
Velocity Impact ◽  
Pull Out ◽  
The Impact

This investigation aims to study the efficiency of STF impregnated plain-weave fabric made of Kevlar under high and low velocity impact conditions. The shear thickening fluid (STF) was prepared by ultrasound irradiation of silica nanoparticles (diameter ≈30 nm) dispersed in liquid polyethylene glycol polymer. STF impregnation effect was determined from single yarn pull-out test and penetration at low velocity using drop weight machine equipped with hemi-spherical penetrator and dynamic force sensor. Force-displacement curves of neat and impregnated Kevlar were analysed and compared. Also, the STF impregnation effect on Kevlar multilayers was analysed from high velocity impact tests using 9mm FMJ bullet at 390 m/s. After impact, Back face deformation (BFD) of neat and impregnated Kevlar layers were measured and compared. Results showed that STF impregnated fabrics have better energy absorption and penetration resistance as compared to neat fabrics without affecting the fabric flexibility. When relative yarn translations are restricted (e.g. at very high levels of friction), windowing and yarn pull-out cannot occur, and the fibres engaged with the projectile fail in tension that leads to fabric penetration. Microscopy of these fabrics after testing have shown pitting and damage to the Kevlar filaments caused by the hard silica particles used in the STF. Mesoscopic 3D Finite Element models were developed using explicit LS-DYNA hydrocode to account for STF impregnation by employing the experimental results of yarn pull-out tests, low and high velocity impacts. It was found that friction between fibers and yarns increase the dissipation of energy upon impact by restricting fiber mobility, increasing the energy required for relative yarn translations and transferring the impact energy to a larger number of fibers.

Natural-hydraulic fracture interaction: Microseismic observations and geomechanical predictions

2015 ◽  
Vol 3 (3) ◽  
pp. SU17-SU31 ◽  
Author(s):  
Jian Huang ◽  
Reza Safari ◽  
Uno Mutlu ◽  
Kevin Burns ◽  
Ingo Geldmacher ◽  
...  
Keyword(s):  
Sensitivity Analysis ◽  
Hydraulic Fracture ◽  
Fracture Network ◽  
Natural Fracture ◽  
Design Parameters ◽  
Reservoir Area ◽  
Complex Fracture ◽  
Model Complex ◽  
Fracture Interaction ◽  
The Impact

Natural fractures can reactivate during hydraulic stimulation and interact with hydraulic fractures producing a complex and highly productive natural-hydraulic fracture network. This phenomenon and the quality of the resulting conductive reservoir area are primarily functions of the natural fracture network characteristics (e.g., spacing, height, length, number of fracture sets, orientation, and frictional properties); in situ stress state (e.g., stress anisotropy and magnitude); stimulation design parameters (e.g., pumping schedule, the type/volume of fluid[s], and proppant); well architecture (number and spacing of stages, perforation length, well orientation); and the physics of the natural-hydraulic fracture interaction (e.g., crossover, arrest, reactivation). Geomechanical models can quantify the impact of key parameters that control the extent and complexity of the conductive reservoir area, with implications to stimulation design and well optimization in the field. We have developed a series of geomechanical simulations to predict natural-hydraulic fracture interaction and the resulting fracture network in complex settings. A geomechanics-based sensitivity analysis was performed that integrated key reservoir-geomechanical parameters to forward model complex fracture network generation, synthetic microseismic (MS) response, and associated conductivity paths as they evolve during stimulation operations. The simulations tested two different natural-hydraulic fracture interaction scenarios and could generate synthetic MS events. The sensitivity analysis revealed that geomechanical models that involve complex fracture networks can be calibrated against MS data and can help to predict the reservoir response to stimulation and optimize the conductive reservoir area. We analyzed a field data set (obtained from two hydraulically fractured wells in the Barnett Formation, Tarrant County, Texas) and established a coupling between the geomechanics and MS within the framework of a 3D geologic model. This coupling provides a mechanics-based approach to (1) verify MS trends and anomalies in the field, (2) optimize conductive reservoir area for reservoir simulations, and (3) improve stimulation design on the current well in near-real-time and well design/stimulation for future wells.

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