scholarly journals Experimental and Theoretical Study on Dynamic Hydraulic Fracture

Energies ◽  
2019 ◽  
Vol 12 (3) ◽  
pp. 397 ◽  
Author(s):  
Jingnan Dong ◽  
Mian Chen ◽  
Yuwei Li ◽  
Shiyong Wang ◽  
Chao Zeng ◽  
...  
Keyword(s):  
Hydraulic Fracturing ◽  
Hydraulic Fracture ◽  
Oil And Gas ◽  
Fluid Velocity ◽  
Crack Tip ◽  
Momentum Balance ◽  
Gas Reservoirs ◽  
Direct Observations ◽  
Total Input ◽  
Theoretical Predictions

Hydraulic fracturing is vital in the stimulation of oil and gas reservoirs, whereas the dynamic process during hydraulic fracturing is still unclear due to the difficulty in capturing the behavior of both fluid and fracture in the transient process. For the first time, the direct observations and theoretical analyses of the relationship between the crack tip and the fluid front in a dynamic hydraulic fracture are presented. A laboratory-scale hydraulic fracturing device is built. The momentum-balance equation of the fracturing fluid is established and numerically solved. The theoretical predictions conform well to the directly observed relationship between the crack tip and the fluid front. The kinetic energy of the fluid occupies over half of the total input energy. Using dimensionless analyses, the existence of equilibrium state of the driving fluid in this dynamic system is theoretically established and experimentally verified. The dimensionless separation criterion of the crack tip and the fluid front in the dynamic situation is established and conforms well to the experimental data. The dynamic analyses show that the separation of crack tip and fluid front is dominated by the crack profile and the equilibrium fluid velocity. This study provides a better understanding of the dynamic hydraulic fracture.

Some challenges in hydraulic fracturing of tight gas reservoirs: an experimental study

2011 ◽  
Vol 51 (1) ◽  
pp. 499 ◽  
Author(s):  
Vamegh Rasouli ◽  
Mohammad Sarmadivaleh ◽  
Amin Nabipour
Keyword(s):  
Hydraulic Fracturing ◽  
Hydraulic Fracture ◽  
Oil And Gas ◽  
Interaction Mechanism ◽  
Natural Fracture ◽  
Gas Reservoirs ◽  
Tight Sandstone ◽  
True Triaxial ◽  
Rock Types ◽  
Interface Parameters

Hydraulic fracturing is a technique used to enhance production from low quality oil and gas reservoirs. This approach is the key technique specifically in developing unconventional reservoirs, such as tight formations and shale gas. During its propagation, the hydraulic fracture may arrive at different interfaces. The mechanical properties and bounding quality of the interface as well as insitu stresses are among the most significant parameters that determine the interaction mechanism, i.e. whether the hydraulic fracture stops, crosses or experiences an offset upon its arrival at the interface. The interface could be a natural fracture, an interbed, layering or any other weakness feature. In addition to the interface parameters, the rock types of the two sides of the interface may affect the interaction mechanism. To study the interaction mechanism, hydraulic fracturing experiments were conducted using a true triaxial stress cell on two cube samples of 15 cm. Sample I had a sandstone block in the middle surrounded by mortar, whereas in sample II the location of mortar and tight sandstone blocks were changed. The results indicated that besides the effect of the far field stress magnitudes, the heterogeneity of the formation texture and interface properties can have a dominant effect in propagation characteristics of an induced fracture.

Effect of Fluid Compressibility on Toughness-Dominated Hydraulic Fractures With Leakoff

SPE Journal ◽  
2018 ◽  
Vol 23 (06) ◽  
pp. 2118-2132 ◽  
Author(s):  
Di Wang ◽  
Mian Chen ◽  
Yan Jin ◽  
Andrew. P. Bunger
Keyword(s):  
Hydraulic Fracturing ◽  
Hydraulic Fracture ◽  
Oil And Gas ◽  
Hydraulic Fractures ◽  
Gas Reservoirs ◽  
Fracturing Fluids ◽  
Fracture Shape ◽  
Carbon Dioxide Co2 ◽  
Fracture Growth ◽  
Fluid Compressibility

Summary Hydraulic fracturing using supercritical carbon dioxide (CO2) has a recognized potential to grow in importance for unconventional oil and gas reservoirs. It is characterized by higher compressibility than traditional liquid-phase hydraulic-fracturing fluids. Motivated by the larger compressibility of supercritical CO2, this paper considers the problem of a hydraulic fracture in which a compressible fluid is injected at a constant rate to drive a hydraulic fracture in a permeable and brittle rock. The two cases of a plane-strain fracture and a penny-shaped fracture are considered. It is shown that for many practical cases, the formation has a large enough fracture toughness that the propagation is in a regime for which the pressure inside the hydraulic fracture can be treated as spatially uniform (“toughness dominated”). Both numerical simulations and analytical solutions for the relevant limiting regimes show that fluid compressibility affects fracture shape only at the very beginning period, which corresponds to the storage regime, and has little effect on fracture growth in the leakoff regime. Overall, because the transition from the storage regime to the leakoff regime is expected to often take place in a short time after the fracture starts propagating, the influence of compressibility in the storage regime is very brief and can be quickly ignored. Therefore, even relatively sizable fluid compressibility has almost no effect on fracture growth in the toughness-dominated regime when leakoff is taken into account.

scholarly journals A numerical investigation on the performance of hydraulic fracturing in naturally fractured gas reservoirs based on stimulated rock volume

2020 ◽  
Vol 10 (8) ◽  
pp. 3333-3345
Author(s):  
Ali Al-Rubaie ◽  
Hisham Khaled Ben Mahmud
Keyword(s):  
Hydraulic Fracturing ◽  
Hydraulic Fracture ◽  
Natural Fracture ◽  
Shear Stresses ◽  
Individual Element ◽  
Natural Fractures ◽  
Gas Reservoirs ◽  
Stimulated Reservoir Volume ◽  
Reservoir Volume ◽  
Naturally Fractured

Abstract All reservoirs are fractured to some degree. Depending on the density, dimension, orientation and the cementation of natural fractures and the location where the hydraulic fracturing is done, preexisting natural fractures can impact hydraulic fracture propagation and the associated flow capacity. Understanding the interactions between hydraulic fracture and natural fractures is crucial in estimating fracture complexity, stimulated reservoir volume, drained reservoir volume and completion efficiency. However, because of the presence of natural fractures with diffuse penetration and different orientations, the operation is complicated in naturally fractured gas reservoirs. For this purpose, two numerical methods are proposed for simulating the hydraulic fracture in a naturally fractured gas reservoir. However, what hydraulic fracture looks like in the subsurface, especially in unconventional reservoirs, remain elusive, and many times, field observations contradict our common beliefs. In this study, the hydraulic fracture model is considered in terms of the state of tensions, on the interaction between the hydraulic fracture and the natural fracture (45°), and the effect of length and height of hydraulic fracture developed and how to distribute induced stress around the well. In order to determine the direction in which the hydraulic fracture is formed strikethrough, the finite difference method and the individual element for numerical solution are used and simulated. The results indicate that the optimum hydraulic fracture time was when the hydraulic fracture is able to connect natural fractures with large streams and connected to the well, and there is a fundamental difference between the tensile and shear opening. The analysis indicates that the growing hydraulic fracture, the tensile and shear stresses applied to the natural fracture.

A Semi-Infinite Hydraulic Fracture Driven by a Herschel–Bulkley Fluid

2019 ◽  
Vol 86 (12) ◽  
Author(s):  
Alena O. Bessmertnykh ◽  
Egor V. Dontsov
Keyword(s):  
Hydraulic Fracturing ◽  
Yield Stress ◽  
Hydraulic Fracture ◽  
Oil And Gas ◽  
Fracture Propagation ◽  
Industrial Process ◽  
Infinite Plane ◽  
Lubrication Equation ◽  
Singular Form ◽  
Non Linear System

Abstract Hydraulic fracturing is an industrial process often applied to enhance oil and gas recovery. Under this process, fractures are generated by the injection of highly pressurized fluids, which often exhibit shear-thinning rheology and yield stress. The global fracture propagation is influenced by various processes occurring near the fracture tip. To gain an insight into fracture propagation, the problem of a semi-infinite hydraulic fracture propagating in a permeable linear elastic rock is solved. To investigate the effect of fluid yield stress, we focus on a fracture driven by Herschel–Bulkley fluid. The mathematical model consists of the elasticity equation, the lubrication equation, and the propagation criterion for the semi-infinite plane strain fracture to obtain the fracture opening. The non-linear system of governing equations is represented in the non-singular form and solved numerically using Newton’s method. The solution is influenced by the competing processes related to rock toughness, fluid properties, and leak-off. The effects of these phenomena prevail at different length scales, and the corresponding limits can be described via analytical solutions. For a Herschel-Bulkley fluid, an additional limiting solution related to the fluid yield stress is obtained, and the regions of the dominance of limiting solutions affected by the yield stress are investigated. Finally, a faster approximate solution for the problem is proposed and its accuracy against a numerical solution is evaluated. The obtained result can be applied in hydraulic fracturing simulators to account for the effect of Herschel–Bulkley fluid rheology on the near-tip region.

Investigating the Use of CO2 as a Hydraulic Fracturing Fluid for Water Sustainability and Environmental Friendliness

2021 ◽  
Author(s):  
Sherif Fakher ◽  
Abdulaziz Fakher
Keyword(s):  
Carbon Dioxide ◽  
Hydraulic Fracturing ◽  
Oil And Gas ◽  
Reservoir Rock ◽  
Future Research ◽  
Strong Impact ◽  
Fracturing Fluid ◽  
Gas Reservoirs ◽  
Environmental Friendliness ◽  
Shale Reservoirs

Abstract Hydraulic fracturing is the process by which many unconventional shale reservoirs are produced from. During this process, a highly pressurized fluid, usually water, is injected into the formation with a proppant. The fracturing fluid breaks the formation thus increasing its permeability, and the proppant ensures that the formation remains open. Although highly effective, hydraulic fracturing has several limitations including relying on a highly valuable commodity such as water. This research investigates the applicability of carbon dioxide as a fracturing fluid instead of water, and studies the main advantages and limitation of such a procedure. The main properties that could have a strong impact on the applicability of carbon dioxide based hydraulic fracturing are studied; these factors include carbon dioxide properties, proppant properties, and reservoir rock, fluid, and thermodynamic properties. This research aims to function as an initial introduction and roadmap to future research investigating the applicability of carbon dioxide as a fracturing fluid in unconventional oil and gas reservoirs.

Hydraulic fracture in earth and rock-fill dams

1990 ◽  
Vol 27 (4) ◽  
pp. 496-506 ◽  
Author(s):  
K. Y. Lo ◽  
Kiny Kaniaru
Keyword(s):  
Hydraulic Fracturing ◽  
Hydraulic Fracture ◽  
Laboratory Tests ◽  
Field Performance ◽  
Degree Of Saturation ◽  
Theoretical Expression ◽  
Test Results ◽  
Rock Fill ◽  
Fracture Pressure ◽  
Theoretical Predictions

Unsatisfactory performance of earth and rock-fill dams involving excessive seepage, piping or failure has been attributed to hydrofracture of the core. Although the phenomenon has been reported for some time, important factors influencing hydraulic fracturing pressure, such as saturation and consolidation, have received relatively little attention; nor have results of laboratory tests or theoretical study been directly related to field performance. In this paper, laboratory hydrofracturing tests under well-defined conditions were performed. A simple theoretical expression for fracture pressure is developed involving only conventional soil strength parameters. Case histories involving hydraulic fracturing of the earthcore are reviewed, and "field" hydraulic fracture pressure and crack closure pressure are defined. The results of the laboratory tests show that hydraulic fracture pressure is not a unique soil property; its value depends on the degree of saturation and consolidation. A comparison of the data deduced from case records with test results and theoretical predictions indicates general consistency. The field hydraulic fracturing pressures are bounded in the upper limit by results from saturated-consolidated tests and in the lower limit by results of saturated–unconsolidated hydraulic fracturing tests. It is suggested that the methodology presented may be useful in the assessment of risk of hydraulic fracturing of dams. Key words: earth and rock-fill dams, hydraulic fracture, tensile strength, seepage, Teton Dam.

scholarly journals A multi-perforation staged fracturing experimental study on hydraulic fracture initiation and propagation

2020 ◽  
Vol 38 (6) ◽  
pp. 2466-2484
Author(s):  
Jianguang Wei ◽  
Saipeng Huang ◽  
Guangwei Hao ◽  
Jiangtao Li ◽  
Xiaofeng Zhou ◽  
...  
Keyword(s):  
Hydraulic Fracturing ◽  
Hydraulic Fracture ◽  
Oil And Gas ◽  
Fracture Initiation ◽  
Fracture Network ◽  
Hydraulic Fractures ◽  
Breakdown Pressure ◽  
Tight Sandstone ◽  
Heterogeneous Samples ◽  
Initiation And Propagation

Hydraulic fracture initiation and propagation are extremely important on deciding the production capacity and are crucial for oil and gas exploration and development. Based on a self-designed system, multi-perforation cluster-staged fracturing in thick tight sandstone reservoir was simulated in the laboratory. Moreover, the technology of staged fracturing during casing completion was achieved by using a preformed perforated wellbore. Three hydraulic fracturing methods, including single-perforation cluster fracturing, multi-perforation cluster conventional fracturing and multi-perforation cluster staged fracturing, were applied and studied, respectively. The results clearly indicate that the hydraulic fractures resulting from single-perforation cluster fracturing are relatively simple, which is difficult to form fracture network. In contrast, multi-perforation cluster-staged fracturing has more probability to produce complex fractures including major fracture and its branched fractures, especially in heterogeneous samples. Furthermore, the propagation direction of hydraulic fractures tends to change in heterogeneous samples, which is more likely to form a multi-directional hydraulic fracture network. The fracture area is greatly increased when the perforation cluster density increases in multi-perforation cluster conventional fracturing and multi-perforation cluster-staged fracturing. Moreover, higher perforation cluster densities and larger stage numbers are beneficial to hydraulic fracture initiation. The breakdown pressure in homogeneous samples is much higher than that in heterogeneous samples during hydraulic fracturing. In addition, the time of first fracture initiation has the trend that the shorter the initiation time is, the higher the breakdown pressure is. The results of this study provide meaningful suggestions for enhancing the production mechanism of multi-perforation cluster staged fracturing.

scholarly journals Assessing the effect of proppant compressibility on the conductivity of heterogeneously propped hydraulic fracture

2021 ◽  
Vol 2057 (1) ◽  
pp. 012078
Author(s):  
A M Skopintsev
Keyword(s):  
Hydraulic Fracture ◽  
Oil And Gas ◽  
Production Performance ◽  
Fracture Aperture ◽  
Strong Impact ◽  
Gas Reservoirs ◽  
Fracture Conductivity ◽  
Fracture Closure ◽  
Oil And Gas Reservoirs ◽  
Treatment Design

Abstract Hydraulic fracturing is a technology that is widely used in the development of oil and gas formations. Given that the fracture closure has a strong impact on production, quantifying the resulting fracture conductivity is critical for optimizing treatment design. The goal of this paper is to better understand the influence of the closing stress on the fracture conductivity when the proppant distribution is heterogeneous. In addition to the spatial proppant distribution, the conductivity of the propped fracture is affected by proppant deformation and embedment. Numerical results indicate that compressibility of proppant can significantly change the residual fracture aperture and, consequently, production performance in oil and gas reservoirs

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