CN-122021158-A - Shale gas well injection parameter selection method of shale fracturing crosstalk prevention and control system based on HMD-DFN coupling

Abstract

The invention discloses a shale gas well injection parameter selection method based on an HMD-DFN coupling shale fracturing crosstalk prevention and control system, and belongs to the technical field of constructional engineering. The method comprises the following steps of 1, establishing a full-coupling model of a fractured rock mass HMD, 2, establishing a multi-horizontal well multi-section staggered type zipper fracturing numerical model based on the full-coupling model of the fractured rock mass HMD in the step 1 and combining the geological conditions of a reservoir stratum and the characteristics of natural fractures, 3, developing fracturing optimization design, quantifying the influences of different injection parameter combinations on fracturing channeling and transformation effects, and 4, dividing an injection parameter response space by taking the number of the fracturing channeling sections and the transformation volume of the reservoir stratum with unit thickness under each working condition as evaluation indexes to obtain recommended injection parameters. The HMD numerical model of the fractured rock mass constructed by the invention can provide theoretical support and field application reference for the field multi-well multi-section injection parameter optimization design to a certain extent.

Inventors

• LIU FUSHEN
• MOU YANG
• LEI WEIXIN
• ZHANG NANLIN

Assignees

• 浙江大学

Dates

Publication Date

20260512

Application Date

20260129

Claims (6)

1. 1. A shale gas well injection parameter selection method based on an HMD-DFN coupling shale fracturing tamper prevention and control system is characterized by comprising the following steps: step1, establishing a full coupling model of a fractured rock mass HMD; Step 2, based on the split rock mass HMD full-coupling model in the step 1, combining the geological conditions of the reservoir of the platform and the characteristics of the natural split, and establishing a multi-horizontal well multi-section staggered zip-type fracturing numerical model; step 3, developing fracturing optimization design, and quantifying influences of different injection parameter combinations on fracturing channeling and transformation effects; And 4, dividing the injection parameter response space by taking the number of the channeling pressing sections and the transformation volume of the reservoir with unit thickness under each working condition as evaluation indexes to obtain recommended injection parameters.
2. 2. The method of claim 1, wherein in step 1, the establishment of the full coupling model of the fractured rock mass HMD adopts a strong coupling method to directly solve a control equation set of each physical field, so as to realize synchronous update and solution output of variables of each physical field.
3. 3. The method according to claim 1, characterized in that in step 2, the actual geological data of the platform reservoir is input as initial conditions into the HMD full-coupling model.
4. 4. A method according to claim 3, wherein the actual geological data comprises geological parameters, information related to natural fractures, information related to injection fluids, construction parameters.
5. 5. The method of claim 1, wherein in step 3, the fracturing optimization design is performed with the construction displacement and the total amount of fracturing fluid as two factor variables.
6. 6. The method of claim 1, wherein in step 4, the injection parameter response space is divided into a recommended region, a conservative region, and a risk region.

Description

Shale gas well injection parameter selection method of shale fracturing crosstalk prevention and control system based on HMD-DFN coupling Technical Field The invention belongs to the technical field of constructional engineering, and relates to a shale gas well injection parameter selection method based on an HMD-DFN coupling shale fracturing crosstalk prevention and control system. Background The problem of frequent horizontal well fracturing crosstalk under the factory development mode has become a key problem for restricting the safe and efficient development of shale gas in China. Although the research of the problem by students at home and abroad has been greatly progressed in recent years, the numerical research of the pressure channeling law and mechanism of the horizontal well is still in the development stage. The current numerical study of the fracture tamper mechanism can be further refined in several aspects: (1) Most studies fail to achieve full coupling of fracture propagation, geomechanics, and fluid flow, while sequential decoupling methods, which solve the physical field equation by step-and-step iterations, lack bi-directional coupling between fracture propagation and geomechanics-fluid flow. The fracturing crosstalk is a result of nonlinear coupling of flow-solid-damage multi-physical field intensity, and the sequential decoupling method is difficult to accurately predict a crosstalk flow path and a risk threshold value because real-time interaction and nonlinear effects of physical fields are ignored, so that the requirement of more accurate simulation of the fracturing crosstalk under complex geological conditions cannot be met. Therefore, it is necessary to consider three-field full coupling in the numerical analysis. (2) Many studies do not well characterize the random distribution and multiscale characteristics of natural fractures in reservoirs. Some models adopt a homogenized reservoir assumption, so that the dominant channel effect of natural cracks on the flow of fracturing fluid cannot be captured, and the risk of fracture crosstalk is seriously underestimated. Some models consider natural fractures, but regularized fracture zone models are commonly used to delineate natural fractures. This is not in agreement with the random distribution of natural fracture networks in actual shale reservoirs as well as the multiscale characteristics explained by logging. Therefore, it is necessary to construct a natural fracture network that is more closely distributed to reality based on the distribution characteristics and scale statistics of natural fractures in the reservoir. (3) Most of the researches generally assume that the opening degree, the rigidity and the permeability of the natural fracture are static constants, and the synergistic effect of normal closure-frictional sliding-shear expansion after the natural fracture is activated is ignored. The linearization treatment leads to the fact that the model cannot characterize the dynamic evolution of the fracture opening and the permeability caused by the effective stress change of the reservoir, and the influence of fracture stiffness-stress dependence on a reservoir flow-solid coupling mechanism is shielded. (4) The fracturing injection scheme is also a key engineering factor influencing fracturing channeling, and the risk of inter-well interference in fracturing operation can be effectively reduced by dynamically adjusting the injection scheme through monitoring the fracture evolution process in real time. At present, a shale gas well injection parameter selection method for effectively reducing the channeling risk and improving the transformation effect is not available. In summary, the prior art still has significant shortcomings, so that a natural fracture nonlinear mechanical model is necessarily introduced, a seepage-mechanical-damage coupling mechanism in the natural fracture activation process in a reservoir is reflected more truly, and a shale gas well injection parameter selection method capable of effectively reducing the pressure channeling risk and improving the transformation effect is provided based on the model. Disclosure of Invention The invention aims to solve the technical problems, and provides a shale gas well injection parameter selection method based on an HMD-DFN coupling shale fracturing crosstalk prevention and control system, which provides theoretical support and field application reference for field multi-well multi-section injection parameter optimization design. In order to achieve the above purpose, the present invention mainly provides the following technical solutions: the embodiment of the invention provides a shale gas well injection parameter selection method based on an HMD-DFN coupling shale fracturing crosstalk prevention and control system, which comprises the following steps: step1, establishing a full coupling model of a fractured rock mass HMD; Step 2, based on the split rock mass HMD ful