A New Method and Application of Full 3D Numerical Simulation for Hydraulic Fracturing Horizontal Fracture

Abstract

The numerical simulation of hydraulic fracturing fracture propagation is the core content of hydraulic fracturing design and construction. Its simulation results directly affect the effect of fracturing, and can effectively guide the fracturing construction plan and reduce the construction risk. At present, two-dimensional or quasi-three-dimensional models are mainly used, but most of them are used to simulate the vertical fracture of hydraulic fracturing. There are errors in the application process. In this paper, a three-dimensional mathematical model, including an elastic rock mechanics equation and a material flow continuity equation, is established to simulate horizontal fracture propagation in shallow reservoirs. The emphasis of this paper is to propose a new method for solving equations. The basic idea of the iteration method has been proposed by previous scholars: Firstly, assuming that the initial pressure of each point in the fracture is uniform, the fracture height of each initial point can be obtained by using Equation (20). Using the initial height values, the pressure values at each point of continuous variation are calculated by Equation (16), and then the new fracture height values are obtained by Equation (20). Because of the equal initial pressure, this method leads to too many iterations in the later stages, which makes the calculation more complicated. In this paper, a new Picca iteration method is proposed. The iteration parameters are changed sequentially. Firstly, the distribution value of fracture height is assumed. Then, the pressure distribution value is calculated according to Equation (16). Then, the new distribution value of fracture height is obtained by bringing the obtained pressure distribution value into Equation (20). Then, the new distribution value of the fracture height is calculated according to Equation (16). The pressure distribution value completes an iteration process until the iteration satisfies the convergence condition. In addition, Sneddon’s model is introduced into the hypothesis of fracture height to obtain the maximum fracture height and assume that the initial fracture profile is a parabola. Finally, the proposed method can rapidly improve the convergence rate. Next, on the basis of investigating the solutions of previous equations, the Galerkin finite element method is used to solve the above equations. The new Picard iteration sequence method is applied to solve the height and pressure at different points in the fracture. By calculating the stress intensity factor, we can judge whether the fracture continues to extend or not, and then simulate the full three-dimensional horizontal fracture of the hydraulic fracturing expansion process. The infiltration process of three types of oil reservoirs in Daqing Changyuan oilfield is simulated. The results show that during the initial fracture stage, the radius and height of fractures increase rapidly, and the rate of increase slows down with the increase of construction time. The height and net pressure of each point in the fracture are unequal. The height and net pressure of the fracture in the wellbore reach the maximum, and gradually decrease to the front of the fracture. Compared with conventional fracturing, the fracturing-flooding percolation process has the characteristics of short fracture-making and large vertical percolation distance, which can greatly increase the swept volume of flooding fluid and thus enhance oil recovery. With the increase in the rock modulus of elasticity, the radius of fractures decreases and the height of fractures increases. With the increase in construction displacement, the radius of fractures hardly changes, the height of fractures increases, and the vertical infiltration distance of the fractures increases. It is suggested that the construction displacement should be 4.0 m3/min. In the range of fracturing fluid viscosity in the studied block, with the change of fracturing fluid viscosity, the change of fracture radius and height is not obvious. In order to further increase sweep volume, the fracturing fluid viscosity should be further reduced.

New Chemical Treatment for Permanent Removal of Condensate Banking from Different Gas Reservoirs

“…26 Several chemicals can be injected to alter the rock wettability from strong liquid-wet to the neutral wettability condition, which will improve the gas productivity for a long time. 2,27 Hydraulic fracturing operations are implemented in the condition of extremely low permeability or significantly high capillary pressure. 23,28 The induced fractures create conductive paths between the reservoir and the wellbore and then enhance the process of condensate removal.…”

An Assessment Method of Sealing Performance and Stress Intensity Factors at Crack Tip of Subsea Connector Metal Sealing Rings

“…Stress intensity factor (SIF) solutions were derived from a finite element model analysis for transverse surface cracks located at five different crack initiation locations in the cross-section of rail steel and thermite weld. Bing Xu et al [14] established a three-dimensional mathematical model, including an elastic rock mechanics equation and a material flow continuity equation, to simulate horizontal fracture propagation in shallow reservoirs. Daobing Wang et al [15] Energies 2022, 15, 4680 3 of 16 investigated the diversion mechanisms of an opened natural fracture intersected by a hydro-fracture in naturally fractured reservoirs by means of the extended finite element method.…”

“…There is no research on crack's influence on the sealing performance of seal rings. As for stress intensity factors at crack tip, although there are some studies on cylinders, pipes, valve body, or other simple structures [7][8][9][10][11][12][13][14][15][16][17], there is no research on crack-tip stress intensity factors of subsea connector sealing rings. In conclusion, there are two main shortages in previous research: (a) cracks' influence on the sealing performance of seal rings was not considered; (b) the crack-tip stress intensity factors study only focused on simple structures.…”

Big Data Analysis and Research on Fracturing Construction Parameters of Shale Gas Horizontal Wells—A Case Study of Horizontal Wells in Fuling Demonstration Area, China

“…Energies 2021, 14, 8357 2 of 17 Various methods have been used to study the optimization of fracturing construction parameters [5][6][7][8][9][10][11]. Some of the more representative methods are the applied mathematical method, the mechanistic model method, and the numerical simulation drawing board method.…”

“…The optimal combination of fracturing parameters is the one that maximizes the postfracturing capacity by optimizing the values of several construction parameters that affect the production of a single well. Tang et al and Xu et al [9,10] developed a mechanistic model through the seepage theory of multistage fractured horizontal wells in shale gas reservoirs to simulate reservoir modification to invert the process and construction design of horizontal wells. Yan et al [11] analyzed the fracture width, height, and length from numerical simulations with fracture construction parameters using the graphical plate method to find the optimal range of fracture construction parameters.…”