Study On Deliverability And Well Test Theory And Application Of High Angle Deviated Well And Horizontal Well In Eastern Sichuan Carboniferous Gas Reservoir

The production practice of eastern Sichuan carboniferous gas reservoir proves that the productivity of gas well has large difference which depending on whether the porosity and fracture of reservoir have developed. If the porosity and fracture develop well. the productivity of gas well could reach up to million of litres. while when the porosity is poor developed. especially when the fracture is underdeveloped. the storage-percolation of reservoir and the productivity of well are usually small. The exploitation of this kind of low permeability reservoir gas is much difficulty, and the economic benefits are poor. But, low permeability reservoir in eastern Sichuan is more common, low permeability reserves account for a large proportion, therefore, studying the reserve producing of low permeability gas reservoir or blocks, the improvement of the exploitation rate of low permeability reservoir and the degree of reserve recovery has important political meaning and economic benefits. In order to improve the reserve producing degree of eastern Sichuan carboniferous gas reservoir low permeability blocks, until now, it has been arranged37high angle derivate well and horizontal well in the eastern Sichuan carboniferous gas reservoir. This paper is based on the study of geological characteristics of eastern Sichuan carboniferous gas reservoir, studying the productivity of high angle derivate well and horizontal well in eastern Sichuan carboniferous gas reservoir, according to the product system analysis of the high angle derivate well and horizontal well and the study of reasonable working system determination method of the gas well, analyze and determine reasonable working system for the high angle derivate well and horizontal well; establish the high angle derivate and horizontal well test analysis model of homogenous, dual porous media, and low permeability gas reservoir, respectively, solve the model and make corresponding typical curve, analyze the filtration characteristic and well test analysis method of high angle derivate well and horizontal well. At last, analyze the production decline law of high angle derivate well and horizontal well. The general contents mainly consist of the following several aspects.(1) The productivity analysis mathematical model which are suitable for the eastern Sichuan carboniferous gas reservoir high angle derivate well and horizontal well are established, the productivity theoretical calculation formula for the high angle derivate well and horizontal well is obtained; combine the political situation of the eastern Sichuan carboniferous gas reservoir high angle derivate well and horizontal well, analyze how the gas layer thickness, well derivation angle, well interval length, skin coefficients and anisotropy impact to the productivity index ratio of the high angle derivate well, horizontal well and straight well; at last, analyze the productivity influence factors for the high angle derivate and horizontal well.(2) The gas filtration model and horizontal wellbore flow model are established, the gas filtration and horizontal wellbore flow coupling methods are studied, the inflow performance of horizontal well is analyzed; at the same time, according to study the vertical and bend section pressure drop calculation model analyze the outflow performance of the high angle derivate well and horizontal well; at last, on the basis of high angle derivate well and horizontal well product system analysis model, using thumb rule, gas productivity index method, nodal system analysis method and considering critical liquids carrying flow rate method, the reasonable working system of horizontal well is determined.(3) The unsteady-state filtration mathematical models of homogenous gas reservoir horizontal well, homogenous gas reservoir high angle derivate and dual porous media gas reservoir horizontal well, low permeability gas horizontal well, under multiple outer boundary conditions, are established, on having the solutions of the mathematical models, the pressure behavior pattern curve are drawn, hence the filtration characteristic and flow moment of the high angle derivate and horizontal well are deeply studied, meanwhile, the sensitivity analysis for the pressure behavior pattern influential factors is made, on the basis of this, the conventional and modern well test analysis methods for the high angle derivate well and horizontal well pressure drop and pressure build-up well test data analysis are perfectly established.(4) The mathematical model of horizontal well production decline analysis is established, the typical curve of production decline analysis is drawn, the main factors of production decline are analyzed.