Coal Rock Perforating Stress Analysis And Reaming Broken Rock Simulation

This paper is a sub-project of the national science and technology major and special large oil and gas fields and coal seam gas development project36"Coalbed Methane Drilling Technology and Equipment Development" study on key technology of horizontal well for Coalbed. With the advent of the21st century, the international community’s demand for energy is growing, but stocks of oil and natural gas in the world is finite, and with the development of the world economy, these non-renewable energy is already going exhausted. Each country is facing a critical situation of conventional energy supply shortage. In this new world situation,each country begins to develop non-conventional energy sources and new energy alternative to gradually substitute oil and gas resources.This paper is on the basic thought of the finite element simulation analysis method, through the finite element software, the model of the corresponding results of analysis and analysis. Finite element method is one of the most widely used one of numerical methods, because the method is based on the assumption of continuity, the early finite element method is used to describe and calculate continuous media. Some scholars, in the use of the continuous shape function, propose strengthening the finite element method, combining materials not uniformity and nonlinear processing, the development of the general finite element method, and apply it to nonlinear fracture analysis.From the domestic and overseas scholars and researchers with years of research, we can get a lot of experience and reference:1. Coal rock has anisotropic features, but with no related calculation standard and a certain number of experimental data, coal rock is still put as continuous, homogeneous and isotropic medium for processing.2. In the shallow geotechnical engineering, such as coal, tunnels, the Coulomb-Moore (Coulomb-Mohr) criterion is used as a rock broken strength basis; for deep stratum, because of confining pressure effect, rock performance for plastic characteristic, should use Drucker-general gulag (Drucker-Prager) criteria.3It is feasible to use the large commercial finite element software (such as i-deas, Ansys, Ansys/ls-dyna ABAQUS,) and coal seam rock mechanics analysis, the key lies in whether the software includes the currently accepted rock material model and failure criteria. Ansys software contains Drucker-Prager material model, that is one of the reasons why this software is used very often in the domestic geotechnical analysis.This paper gets the coal rock material mechanics relevant data from the related literature at home and abroad, it provides the factual material parameters for coal rock reaming. This article tries to analyze coal rock reaming finite element simulation from the numerical simulation direction, mainly including coal and rock stress redistribution of perforating analysis, perforation of coal and rock to enlarge hole of cutting force analysis and write a set of simulation software.This research includes: 1. The introduction section:collecting related literature material at home and abroad, assess the feasibility of numerical simulation, thus providing the basis for analyzing coal rock cutting reaming and through the finite element software.2. coal rock properties:comparing rock material mechanics behavior and relevant data of the domestic main area of coal, thus providing reliable coal rock property and parameters for the numerical simulation.3. Coal rock perforating stress redistribution research:with large general finite element software Ansys, this paper analyzes three different original borehole, two different cloth hole scheme, four kinds of cloth hole parameters, the coal rock strata pressure, in the lateral confining pressure and well inside the eye under the joint action of hydrostatic pressure, gas-injection-production well section of the law stress analysis, put forward the recommended value of the hole distance; Analyzing the borehole drilling fluid density gas-injection-production well within the period of the stress distribution and plastic deformation affected, provides the reference for the engineering application4. Using Ansys/ls-dyna explicit dynamic analysis software, focusing on a kind of typical borehole diameter, it simulates on the conditions of no small holes, single holes and a pucker arranged hole cases, the cutting tool in different position of cutting process, concludes the characteristics of change of the coal rock stress distribution, and reaching the time calculation results and average cutting force data which vary according to the cutting force which changes with time and compare it with conventional experience data. It analyzes the borehole drilling fluid density on the cutting force within the effects for engineering application and provides reference data.5. With VB as the platform, Ansys finite element engagement and every item, it develops a set of calculation analysis software which simulates the gas-injection-production well section stress distribution and cutting process dynamics, can be used as reference to the user for actual engineering of the analysis and calculation theory.This paper can study and analysis, to enlarge hole of coal and rock stress distribution again after a the direct-viewing understanding and the understanding, and the different cloth hole scheme comparison analysis, it is concluded that the corresponding cloth hole scheme. Through the dynamics analysis, know the knife cutting the process of coal and rock, the stress of coal and rock various characteristics of the changes and the hole scheme to the effect of cutting force size. Through the VB platform, engage large finite element analysis software ANSYS and ANSYS/ls-dyna and the post-processing software LS-PREPOST, write a engineering and technical personnel can quickly operation of the software. Through the software can realize the implicit perforating stress analysis, explicit dynamics analysis, cutting animated simulation etc. Function. Although the paper makes certain amount of analysis, but there still exists many places for further analysis, for example:it can obtain concrete parameters of the rock through experiment so as to provide the reliable data to finite element analysis. It can draw further conclusion by analyzing more examples, and optimizing it through more reliable analysis process, more detailed analysis of the numerical simulation steps, and using more human software interface to realize more convenient human-machine interaction operation, etc.