Research On Horizontal Well Segmental Fracturing Completed Pipe String And Its Supporting Tools

Reserves of low permeability oil and gas reservoir that accounts for the proportion of total reserves in Dagang oil field is more and more big, under the condition of current energy crisis, the development of low permeability oil and gas reservoir is very important. Exploitation of low porosity and low permeability reservoir mostly have the characteristics of insufficient energy, alone with the horizontal well drilling in improving reservoir development rate and increasing oil drainage area cannot achieve efficient economic development, requires be combined with horizontal well sectional fracturing measures to increase production in the process of completion. However, the horizontal well sectional fracturing measures is a world-class problem, the technical difficulties is the choice of sectional fracturing method and downhole tool for separating that there exists a large gap with the actual demand. Therefore, the improved design, R&D and supporting the integrated application for sectional fracturing completion tools is the urgent need, which provide completion technology support and protection for the exploration and development of non-conventional oil and gas reservoir.Through the method of design, theoretical analysis, experimental design and calculation, domestic research for this technology is still in its infancy. The research content mainly including two sections, is respectively the horizontal well casing cementing sectional fracturing string design and mechanical analysis of fracturing string, as well as the research of pipe string matching tools. Around these two sections, mainly carried out the following tasks:Studied on structural design and mechanical analysis of the horizontal well casing cementing sectional fracturing string. On the basis of pipe string design principles, the structure of sectional fracturing string is designed. Studied the geometric conditions of rigid fracturing string into the well to solve the problem that fracturing string matching tools stuck in kick-off section, because the diameter or length of tools is unreasonable design. Completed mechanics analysis between the string and borehole wall during getting into well, the calculation formula of axial force and friction force was gived and applied to the engineering examples. Ultimately, the difficult point is to find out.The matching tools of casing cementing sectional fracturing string is studied. Basic structure, working principle and technical parameters of each tool is listed. And reliability test of matching tools is designed. Mechanical model is established between sliding sleeve and pressure-out ball. Completed calculation of the cementing sliding sleeve size dimensions and throttle differential pressure.Studied the casing cementing sleeve sealing performance. Under the extreme conditions, completed reliability analysis to determine the best material. The non-linear contact mechanics model is established between the tee and ball. Under the different hydraulic conditions, the equivalent stress and strain of ball and tee is analyzed. Analyzed the maximum stress value, maximum strain value, maximum elastic deformation and plastic deformation changing with hydraulic pressure. Studied the influence of tee taper angle on sealing performance between tee and pressure-out ball, in order to determine the most reasonable tee taper angel to meet fracturing requirements.Studied the casing cementing sliding sleeve erosion wear rule, and a new thread of researches in erosion wear is provided. Firstly, in the study, a flow field model of sliding sleeve is established, so that study on the erosion rate and sand fluid flow characteristics, concluded that the main reason for the erosion damage and critical failure location. The relationship between the erosion wear degree and fracturing liquid flow rate, outlet pressure, sand-carrying capacity and particle diameter is studied. The erosion wear was quantitative calculation, and summed up the relationship curve of erosion depth and erosion time. Finally, on the basis of the relationship curve, the safety time of sliding sleeve is calculated.