Prediction of fracture initiation pressure in multiple failure hydraulic fracturing modes: Three-dimensional stress model considering borehole deformation

2021 ◽  
Vol 199 ◽  
pp. 108264
Author(s):  
Jianyu Zhong ◽  
Zhaolong Ge ◽  
Yiyu Lu ◽  
Zhe Zhou ◽  
Jingwei Zheng
Keyword(s):  
Hydraulic Fracturing ◽  
Three Dimensional ◽  
Fracture Initiation ◽  
Stress Model ◽  
Initiation Pressure

Challenges in hydraulic fracturing from perforated boreholes in unconventional reservoirs

2014 ◽  
Vol 54 (1) ◽  
pp. 285
Author(s):  
Seyed Hassan Fallahzadeh Abarghooei ◽  
Vamegh Rasouli
Keyword(s):  
Hydraulic Fracturing ◽  
Three Dimensional ◽  
Fracture Initiation ◽  
Unconventional Reservoirs ◽  
Tight Sandstone ◽  
Initiation Mechanism ◽  
Stress Regime ◽  
Hydrocarbon Production ◽  
Tight Formations ◽  
Tight Formation

In recent years, with the evolution of unconventional reservoirs, hydraulic fracturing has been applied to tight sandstone and shale formations to improve the hydrocarbon production. The application of hydraulic fracturing in cased boreholes is always associated with many difficulties because the fracture has to be initiated from the perforations. There have been many cases of improper fracture initiation in tight formations, which have then resulted in premature screen out, and have not improved reservoir production. In this study, initiation of hydraulic fracturing from a perforated tunnel was studied numerically using a finite element method. The numerical model was generated to represent a laboratory experimental test, which has been carried out on tight concrete cubic samples. A perforated wellbore in a linearly elastic tight formation was modelled using Abaqus software through three-dimensional numerical analysis. Two different perforation orientations were considered to analyse the fracture initiation pressure (FIP) and the location and initial direction of the crack. Different far field stresses were considered to study the effect of in-situ stresses and perforation directions on the fracture initiation mechanism. The results were then compared to laboratory and analytical outcomes, and good agreement was observed. The results provide a better understanding on how the stress regime, stress anisotropy, and perforation orientation could affect the pressure and geometry of fracture initiation in tight formations. Based on the outcomes of this study, better strategies can be decided for perforating a cased wellbore in a tight formation so that lower FIP is experienced and a better near wellbore fracture is created.

Hydraulic Fracturing Mechanical Mechanism Analyses for Soft Seams Considering Strain Softening Character

2013 ◽  
Vol 868 ◽  
pp. 319-325 ◽  
Author(s):  
Yi Lei ◽  
Wen Bin Wu
Keyword(s):  
Plastic Deformation ◽  
Elastic Modulus ◽  
Internal Friction ◽  
Hydraulic Fracturing ◽  
Poisson’S Ratio ◽  
Strain Softening ◽  
Fracture Initiation ◽  
Poisson's Ratio ◽  
Angle Of Internal Friction ◽  
Initiation Pressure

Mathematical model based on elasticity is not suitable for soft seam hydraulic fracturing mechanism study because its intensity is small, Poisson's ratio is relatively large, and its prone to plastic deformation. Based on plastic mechanics, the theory of large deformation and fracture mechanics theory, hydraulic fracturing of soft coal seam is divided into three phases, namely, coal bed compaction, fracture initiation and crack propagation from the view of the deformation mechanism, the occurring and developing mechanism. The initiation pressure of soft seams considered strain softening character after plastic deformation is obtained on the basis of above. The result shows that the initiation pressure is related to elastic modulus, Poisson's ratio, the angle of internal friction and residual strength. Elastic modulus is inversely proportional to the initiation pressure, the greater its value, the smaller the initiation pressure; but Poisson's ratio, the angle of internal friction and the residual strength and fracture initiation pressure is directly proportional relationship, the greater its value, since the smaller the crack pressure.

scholarly journals Complexing the hydraulic fracturing simulation results when hybrid acid-propant treatment performing and with the simultaneous hydraulic fracture initiation in separated intervals

2021 ◽  
pp. 103-111
Author(s):  
I. G. Fattakhov ◽  
◽  
L. S. Kuleshova ◽  
R. N. Bakhtizin ◽  
V. V. Mukhametshin ◽  
...  
Keyword(s):  
Statistical Analysis ◽  
Hydraulic Fracturing ◽  
Qualitative Data ◽  
Three Dimensional ◽  
Fracture Initiation ◽  
Data Series ◽  
Hydraulic Fractures ◽  
Data Generation ◽  
Data Preparation ◽  
New Approach

The purpose of the work is to substantiate and formulate the principles of data generation with multiple results of hydraulic fracturing (HF) modeling. Qualitative data for assessment, intercomparison and subsequent statistical analysis are characterized by a single numerical value for each considered hydraulic fracturing parameter. For a number of hydraulic fracturing technologies, uncertainty may arise due to obtaining several values for the parameter under consideration. The scientific novelty of the work lies in the substantiation of a new approach for evaluating the obtained data series during hydraulic fracturing modeling. A number of data can be obtained both during the formation and modeling of several hydraulic fractures, and for one fracture when calculating in different modules of the simulator. As a result, an integration technique was developed that allows forming a uniform data array regardless of the number of elements in the hydraulic fracturing modeling results. Keywords: hydraulic fracturing; acid-proppant hydraulic fracturing; hydraulic fracturing of layered rocks; hydraulic fracturing modeling; pseudo-three-dimensional fracture model; data preparation; statistical analysis.

Stimuli-responsive/rheoreversible hydraulic fracturing fluids as a greener alternative to support geothermal and fossil energy production

2015 ◽  
Vol 17 (5) ◽  
pp. 2799-2812 ◽  
Author(s):  
H. B. Jung ◽  
K. C. Carroll ◽  
S. Kabilan ◽  
D. J. Heldebrant ◽  
D. Hoyt ◽  
...  
Keyword(s):  
Hydraulic Fracturing ◽  
Igneous Rock ◽  
Volume Expansion ◽  
Energy Production ◽  
Fracture Initiation ◽  
Stimuli Responsive ◽  
Fossil Energy ◽  
Fracturing Fluids ◽  
Initiation Pressure

A reversible CO2-triggered volume expansion significantly lowers the fracture initiation pressure in highly impermeable igneous rock as compared to conventional fracturing fluids.

scholarly journals Fracture Initiation Model of Shale Fracturing Based on Effective Stress Theory of Porous Media

Geofluids ◽  
2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
Yuwei Li ◽  
Dan Jia
Keyword(s):  
Porous Media ◽  
Mechanical Characteristics ◽  
Oil And Gas ◽  
Elastic Anisotropy ◽  
Special Kind ◽  
Fracture Initiation ◽  
Propagation Mechanism ◽  
Stress Theory ◽  
Unconventional Oil And Gas ◽  
Initiation Pressure

Unconventional oil and gas are important resources of future energy supply, and shale gas is the focus of the development of unconventional resources. Shale is a special kind rock of porous medium, and an orderly structure of beddings aligned in the horizontal direction where causing the strong elastic anisotropy of shale is easy. A new model has been established to calculate the fracture initiation pressure with the consideration of mechanical characteristics of shale and the anisotropic tensile strength when judging rock failure. The fracture initiation model established in this paper accurately reflects the stress anisotropy and matches well with the actual situation in porous media. Through the sensitivity analysis, the results show that σv/σH, Ev/EH, υv/υH, m/s, and A/B have a certain impact on the tangential stress when the circumferential angle changes, and there is a positive relationship between the initiation pressure and the above sensitive factors except for A/B. The results can provide a valuable and effective guidance for the prediction of fracture initiation pressure and fracture propagation mechanism under special stratum conditions of shale.

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.

Sign in / Sign up

Export Citation Format

Share Document