Horizontal Well Drilling Fluid Percolation And Pollution Evaluation Research

The application of drilling fluid is of great significance to the development of oil and gas industry, can realize fast drilling, shorten well completion period, so as to improve the comprehensive benefit of oil and gas exploration and development.But in the process of drilling fluid will invade the reservoir, reservoir pollution and damage caused by, resulting in a decline in oil production and reduce the development efficiency.In order to better protect reservoir, studied the intrusion of drilling fluid and evaluate the pollution around the horizontal well is very important.In this paper, the mechanism of drilling fluid invasion, drilling fluid in reservoir pollution mechanism and influence factors to the degree of reservoir pollution, in the process of the research into the reservoir damage mechanism and main reason, to find the regularity of the change of rock physical properties, chemical properties.Analysis of drilling fluid percolation law, research on drilling fluid invasion depth and the amount of pollution area average permeability and skin factor.In this paper, based on the basic principle of finite element method, the oil-water two phase seepage finite element equation is deduced.Using finite element numerical simulation software simulation of two phase flow in the drilling fluid invasion process, respectively, to study the drilling time, drilling mud cake permeability, pressure difference and the influence law of mud viscosity of drilling fluid invasion depth.According to the simulation of the drilling fluid invasion depth data, and further calculate the pollution area average permeability and skin factor, to evaluate the pollution situation, horizontal well drilling process for the protection of the medium oil gas and the stimulation of scientific decision to provide important basis.