Layer | Fill | Outline |
---|
Map layers
Theme | Visible | Selectable | Appearance | Zoom Range (now: 0) |
---|
Fill | Stroke |
---|---|
Collaborating Authors
Results
Abstract The paper presents three-dimensional numerical model for multiple fracture propagation from the horizontal wells. A 3D numerical model is developed using a combination of the displacement discontinuity method and the finite element method. The reservoir rock mass is assumed homogenous, isotropic, and linear elastic. The fluid flow inside the fracture is assumed laminar flow and the fluid follows Newtonian behavior. The Galerkin’s finite element approach is used for the fluid flow modeling, the rock mass deformation is simulated using the elastic displacement discontinuity method, and the crack tip displacement approach is implemented for mixed-mode fracture propagation. Details of mathematical formulations and methodology for numerical implementation are presented first. Then, the numerical model is verified with some known analytical and semi-analytical solutions. Finally, numerical examples of planar and non-planar multiple fracture propagation in case for sequential and simultaneous fracturing procedure in the Niobrara Chalk formation have been presented. The results demonstrate the effects of in-situ stress, rock and fluid properties, and the "stresses shadowing" effect which mainly depends on the spatial interval between the fractures plays a critical role in the multiple fracture propagation. 1. INTRODUCTION Horizontal well fracturing is applied to improve well productivity from lower quality reservoirs that could not have been economically developed using the conventional fracturing methods. The idea of simulation by hydraulic fracturing is to create a large volume of fractured rock with enhanced permeability with multistage fracturing. The multi-stage fracturing is carried out either in simultaneous or sequential manner from perforation clusters. In case of simultaneous fracturing, the multiple fractures are created and propagated at same time from clusters, whereas in case of sequential fracturing, the fractures are created from one cluster after another usually by keeping the previously created fracture either propped or pressurized with fluid [1]. Several numerical models have been presented to study multiple and multistage fracturing from the single and multiple horizontal well. Most are based on analytical stress analysis method [2, 3], semi-analytical method [4], 2D numerical fracture mechanics models [1, 5] or planar 3D model [6]. Stephen et al. [7] have presented a 3D model based on boundary element method for simultaneous propagation of multiple fractures from a single horizontal well. In this paper, we present a 3D boundary element model with capabilities to simulate any number of fractures in case of simultaneous or sequential propagation schemes from a single or multiple horizontal wells. The main emphasis have been given to evaluate the influences of induce stresses change or "stress shadowing" effect on the multiple fracture propagation.
- North America > United States > California (0.46)
- North America > United States > Oklahoma (0.28)
- North America > United States > Wyoming (0.28)
- Research Report > New Finding (0.66)
- Research Report > Experimental Study (0.48)
- North America > United States > Wyoming > Laramie Basin > Niobrara Formation (0.99)
- North America > United States > Nebraska > Laramie Basin > Niobrara Formation (0.99)
- North America > United States > Kansas > Laramie Basin > Niobrara Formation (0.99)
- (2 more...)
Abstract The paper presents numerical modeling of experimental scale study of hydraulic fracture initiation and propagation for creation of Enhanced Geothermal Systems. The displacement discontinuity method, which is a variant of the boundary element method, is used to model the rock matrix deformation and stress distribution around the fracture surface. Parabolic crack tip elements are used to account for square root variation of the fracture front displacement and stresses. Newtonian fracturing fluid flow is modeled using the standard Galerkin’s Finite Element Method. The fracture initiation and propagation process are addressed following the linear elastic fracture mechanics. The hydraulic fracture simulation process presents a complex numerical problem in which physical processes involved such as rock matrix deformation, fracture fluid flow, and fracture propagation are interdependent. The fracture aperture strongly influences the fluid flow behavior inside the fracture, as the fluid velocity is a function of the fracture aperture, and the fluid pressure influences rock deformation process. Hence, these processes of the fluid flow, the fracture deformation, and the fracture propagation are solved in a coupled manner using sequential iterative approach till the convergence is achieved. First, details of the mathematical model and methodology are presented. The model is then tested against some known analytical and semi-analytical solutions. Finally, the hydraulic fracturing results from a true triaxial EGS experimental cell developed at Colorado School of Mines are used to validate numerical model results. 1. INTRODUCTION Hydraulic fracturing is considered the primary means of creating functional geothermal reservoirs at sites where the permeability of rock is too limited to allow cost effective heat recovery. The natural and hydraulically created fractures provide conductive paths to the stored hydrocarbons or thermal energy in the reservoir rocks to the wellbore thereby increasing the production rates. Stimulation technology and methodology as used in the oil and gas industry for sedimentary formations are well developed; however, they have not sufficiently been demonstrated for the Enhanced Geothermal Systems (EGS) reservoir creation. Insufficient data and measurements under geothermal conditions make it difficult to directly translate experience from the oil and gas industries to EGS applications. Creation of the EGS reservoirs requires an improved fracturing methodology, rheologically controllable fracturing fluids, and temperature hardened proppants.
- North America > United States > Texas (0.68)
- North America > United States > California (0.46)
- Energy > Renewable > Geothermal > Geothermal Resource (1.00)
- Energy > Oil & Gas > Upstream (1.00)
- Energy > Renewable > Geothermal > Geothermal Resource for Power Generation > Enhanced Geothermal System (0.80)