scholarly journals Recent comprehensive review for extended finite element method (XFEM) based on hydraulic fracturing models for unconventional hydrocarbon reservoirs

2020 ◽  
Vol 10 (8) ◽  
pp. 3319-3331 ◽  
Author(s):  
Belladonna Maulianda ◽  
Cindy Dhevayani Savitri ◽  
Aruvin Prakasan ◽  
Eziz Atdayev ◽  
Twon Wai Yan ◽  
...  
Keyword(s):  
Finite Element ◽  
Hydraulic Fracturing ◽  
Fracture Initiation ◽  
In Situ Stress ◽  
Extended Finite Element ◽  
Gas Reservoirs ◽  
Initiation And Propagation ◽  
Unconventional Gas Reservoirs ◽  
In Situ Stress Field

Abstract Hydraulic fracturing has been around for several decades since 1860s. It is one of the methods used to recover unconventional gas reservoirs. Hydraulic fracturing design is a challenging task due to the reservoir heterogeneity, complicated geological setting and in situ stress field. Hence, there are plenty of fracture modelling available to simulate the fracture initiation and propagation. The purpose of this paper is to provide a review on hydraulic fracturing modelling based on current hydraulic fracturing literature. Fundamental theory of hydraulic fracturing modelling is elaborated. Effort is made to cover the analytical and numerical modelling, while focusing on eXtended Finite Element Modelling (XFEM).

Fracture Initiation and Propagation in a Deep Shale Gas Reservoir Subject to an Alternating-Fluid-Injection Hydraulic-Fracturing Treatment

SPE Journal ◽  
2019 ◽  
Vol 24 (04) ◽  
pp. 1839-1855 ◽  
Author(s):  
Bing Hou ◽  
Zhi Chang ◽  
Weineng Fu ◽  
Yeerfulati Muhadasi ◽  
Mian Chen
Keyword(s):  
Hydraulic Fracturing ◽  
Shale Gas ◽  
Fracture Initiation ◽  
Fluid Injection ◽  
Hydraulic Fractures ◽  
Stress Difference ◽  
Gas Reservoirs ◽  
Complex Fracture ◽  
Initiation And Propagation

Summary Deep shale gas reservoirs are characterized by high in-situ stresses, a high horizontal-stress difference (12 MPa), development of bedding seams and natural fractures, and stronger plasticity than shallow shale. All of these factors hinder the extension of hydraulic fractures and the formation of complex fracture networks. Conventional hydraulic-fracturing techniques (that use a single fluid, such as guar fluid or slickwater) do not account for the initiation and propagation of primary fractures and the formation of secondary fractures induced by the primary fractures. For this reason, we proposed an alternating-fluid-injection hydraulic-fracturing treatment. True triaxial hydraulic-fracturing tests were conducted on shale outcrop specimens excavated from the Shallow Silurian Longmaxi Formation to study the initiation and propagation of hydraulic fractures while the specimens were subjected to an alternating fluid injection with guar fluid and slickwater. The initiation and propagation of fractures in the specimens were monitored using an acoustic-emission (AE) system connected to a visual display. The results revealed that the guar fluid and slickwater each played a different role in hydraulic fracturing. At a high in-situ stress difference, the guar fluid tended to open the transverse fractures, whereas the slickwater tended to activate the bedding planes as a result of the temporary blocking effect of the guar fluid. On the basis of the development of fractures around the initiation point, the initiation patterns were classified into three categories: (1) transverse-fracture initiation, (2) bedding-seam initiation, and (3) natural-fracture initiation. Each of these fracture-initiation patterns had a different propagation mode. The alternating-fluid-injection treatment exploited the advantages of the two fracturing fluids to form a large complex fracture network in deep shale gas reservoirs; therefore, we concluded that this method is an efficient way to enhance the stimulated reservoir volume compared with conventional hydraulic-fracturing technologies.

scholarly journals Numerical Simulation of Artificial Fracture Propagation in Shale Gas Reservoirs Based on FPS-Cohesive Finite Element Method

Geofluids ◽  
2019 ◽  
Vol 2019 ◽  
pp. 1-16 ◽  
Author(s):  
Xiaoqiang Liu ◽  
Zhanqing Qu ◽  
Tiankui Guo ◽  
Ying Sun ◽  
Zhifeng Shi ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Finite Element ◽  
Hydraulic Fracturing ◽  
In Situ Stress ◽  
Natural Fracture ◽  
Natural Fractures ◽  
Rock Matrix ◽  
Gas Reservoirs ◽  
Artificial Fracture

The simulation of hydraulic fracturing by the conventional ABAQUS cohesive finite element method requires a preset fracture propagation path, which restricts its application to the hydraulic fracturing simulation of a naturally fractured reservoir under full coupling. Based on the further development of a cohesive finite element, a new dual-attribute element of pore fluid/stress element and cohesive element (PFS-Cohesive) method for a rock matrix is put forward to realize the simulation of an artificial fracture propagating along the arbitrary path. The effect of a single spontaneous fracture, two intersected natural fractures, and multiple intersected spontaneous fractures on the expansion of an artificial fracture is analyzed by this method. Numerical simulation results show that the in situ stress, approaching angle between the artificial fracture and natural fracture, and natural fracture cementation strength have a significant influence on the propagation morphology of the fracture. When two intersected natural fractures exist, the second one will inhibit the propagation of artificial fractures along the small angle of the first natural fractures. Under different in situ stress differences, the length as well as aperture of the hydraulic fracture in a rock matrix increases with the development of cementation superiority of natural fractures. And with the increasing of in situ horizontal stress differences, the length of the artificial fracture in a rock matrix decreases, while the aperture increases. The numerical simulation result of the influence of a single natural fracture on the propagation of an artificial fracture is in agreement with that of the experiment, which proves the accuracy of the PFS-Cohesive FEM for simulating hydraulic fracturing in shale gas reservoirs.

In situ stress and mechanical properties of unconventional gas reservoirs

2022 ◽  
pp. 83-106
Author(s):  
Yong Li ◽  
Jianghao Yang ◽  
Jianqi Chen ◽  
Xiaotian Ma ◽  
Jianchao Cai
Keyword(s):  
Mechanical Properties ◽  
In Situ Stress ◽  
Gas Reservoirs ◽  
Unconventional Gas ◽  
Unconventional Gas Reservoirs

Hydraulic Fracturing Process: Roles of In Situ Stress and Rock Strength

2012 ◽  
Vol 616-618 ◽  
pp. 435-440
Author(s):  
Yan Jun Feng ◽  
Xiu Wei Shi
Keyword(s):  
Hydraulic Fracturing ◽  
Analytical Model ◽  
Field Experiments ◽  
Rock Strength ◽  
Fracture Initiation ◽  
In Situ Stress ◽  
Experimental Investigations ◽  
Propagation Process ◽  
Fracturing Process

This paper presents results of a comprehensive study involving analytical and field experimental investigations into the factors controlling the hydraulic fracturing process. Analytical theories for fracture initiation of vertical and horizontal borehole are reviewed. The initiation and propagation process of hydraulic fracturing is performed in the field by means of hydraulic fracturing and stepwise hydraulic fracturing, the effect of factors such as in-situ stress and rock strength on fracture propagation process is studied and discussed. The fracture initiation pressures estimated from the analytical model and field experiments are compared as well as the fracturing process during case 1and case 2. Results from the analytical model and field experiments conducted in this study are interpreted with a particular effort to enlighten the factors controlling the hydraulic fracturing process.

Finite Element Model Simulations Associated With Hydraulic Fracturing

1982 ◽  
Vol 22 (02) ◽  
pp. 209-218 ◽  
Author(s):  
Sunder H. Advani ◽  
J.K. Lee
Keyword(s):  
Finite Element ◽  
Hydraulic Fracturing ◽  
Finite Element Model ◽  
Hydraulic Fracture ◽  
Element Model ◽  
In Situ Stress ◽  
Fracture System ◽  
Model Simulations ◽  
Fracture Fluid

Abstract Recently emphasis has been placed on the development and testing of innovative well stimulation techniques for the recovery of unconventional gas resources. The design of optimal hydraulic fracturing treatments for specified reservoir conditions requires sophisticated models for predicting the induced fracture geometry and interpreting governing mechanisms. This paper presents methodology and results pertinent to hydraulic fracture modeling for the U.S. DOE's Eastern Gas Shales Program (EGSP). The presented finite-element model simulations extend available modeling efforts and provide a unified framework for evaluation of fracture dimensions and associated responses. Examples illustrating the role of multilayering, in-situ stress, joint interaction, and branched cracks are given. Selected comparisons and applications also are discussed. Introduction Selection and design of stimulation treatments for Devonian shale wells has received considerable attention in recent years1-3. The production of natural gas from such tight eastern petroliferous basins is dependent on the vertical thickness of the organically rich shale matrix, its inherent fracture system density, anisotropy, and extent, and the communication-link characteristics of the induced fracture system(s). The investigation of stimulation techniques based on resource characterization, reservoir property evaluation, theoretical and laboratory model simulations, and field testing is a logical step toward the development of commercial technology for optimizing gas production and related costs. This paper reports formulations, methodology, and results associated with analytical simulations of hydraulic fracturing for EGSP. The presented model extends work reported by Perkins and Kern,4 Nordgren,5 Geertsma and DeKlerk,6 and Geertsma and Haafkens.7 The simulations provide a finite-element model framework for studying vertically induced fracture responses with the effects of multilayering and in-situ stress considered. In this context, Brechtel et al.,8 Daneshy,9 Cleary,10 and Anderson et al.11 have done recent studies addressing specific aspects of this problem. The use of finite-element model techniques for studying mixed-mode fracture problems encountered in dendritic fracturing and vertical fracture/joint interaction also is illustrated along with application of suitable failure criteria. Vertical Hydraulic Fracture Model Formulations Coupled structural fracture mechanics and fracture fluid response models for predicting hydraulically induced fracture responses have been reported previously.12,13 These simulations incorporate specified reservoir properties, in-situ stress conditions, and stimulation treatment parameters. One shortcoming of this modeling effort is that finite-element techniques are used for the structural and stress intensity simulations, while a finite-difference approach is used to evaluate the leakoff and fracture-fluid response in the vertical crack. A consistent framework for conducting all simulations using finite-element modeling is formulated here.

scholarly journals Finite Element Optimised Back Analysis of In Situ Stress Field and Stability Analysis of Shaft Wall in the Underground Gas Storage

2016 ◽  
Vol 2016 ◽  
pp. 1-12 ◽  
Author(s):  
Yifei Yan ◽  
Bing Shao ◽  
Jianguo Xu ◽  
Xiangzhen Yan
Keyword(s):  
Finite Element ◽  
Stress Field ◽  
Geometric Model ◽  
Back Analysis ◽  
Gas Storage ◽  
In Situ Stress ◽  
Underground Gas Storage ◽  
Measured Stress ◽  
In Situ Stress Field

A novel optimised back analysis method is proposed in this paper. The in situ stress field of an underground gas storage (UGS) reservoir in a Turkey salt cavern is analysed by the basic theory of elastic mechanics. A finite element method is implemented to optimise and approximate the objective function by systematically adjusting boundary loads. Optimising calculation is performed based on a novel method to reduce the error between measurement and calculation as much as possible. Compared with common back analysis methods such as regression method, the method proposed can further improve the calculation precision. By constructing a large circular geometric model, the effect of stress concentration is eliminated and a minimum difference between computed and measured stress can be guaranteed in the rectangular objective region. The efficiency of the proposed method is investigated and confirmed by its capability on restoring in situ stress field, which agrees well with experimental results. The characteristics of stress distribution of chosen UGS wells are obtained based on the back analysis results and by applying the corresponding fracture criterion, the shaft walls are proven safe.

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