Study On Quick Bifurcation Technology For Shaping Side Drilling Of Deep Well / Ultra - Deep Well Casing

In the past twenty years, the exploitation of natural gas and petroleum in China has entered the deep strata gradually. Deep oil and gas resources in Sichuan Puguang, Tarim, Xinjiang and sea area as the representative have become China’s main oil and gas production area slowly.Therefore, deep and ultra-deep sidetracking will become one of the main measures in the late period of Oilfield Mining for deep residual oil and gas reservoirs. According to literature data, has proven that the deep oil and gas resources in China are mainly distributed in the depth of4000-8000meters.At present, the domestic5000meters deep sidetracking wells quantity is increasing, the disposable opening success rate is below70%, and the main reason is the lack of understanding of specificity of the deep well casing sidetracking.This particularity is mainly reflected in the casings wall is thick, high strength and the formation is hard and poor drill-ability with a large plasticity because of the pressure. The existing tools are not sufficient to overcome high-strength metals and poor drill-ability rock at the same time, so it difficult to separate the tool with the original hole. It has a greatly influence to the sidetracking operations.Therefore, for deep/ultra-deep sidetracking fast branch technology research has the important practical significance and development prospects.In this paper, in view of the specificity of deep/ultra-deep sidetracking, we have made a research and designed new casing sidetracking tool for ultra-deep well and complete the process technology.Before the designing of high efficient deep well casing sidetracking tool, first of all, we reading a lot of literatures and do some field investigation, established the design scheme;By study the mutual cutting and wear mechanismsof the Whip-stock, casing, bit, and the rock around the casing, we innovative design a whip-stock with composite guide surface, three hydraulic cylinder linkage pressure, double slip packer and also designed adouble-acting bit.The tool has the advantages of high strength, good reliability, Large angle of bifurcation, faster branch speed, so, it can effectively solve the quickly bifurcation sidetracking operations in deep and ultra-deep wells.Based on finite element analysis shows that, slip of new whip-stock can get in the casing wall under the liquid pressure of20～25MPa, and when the it bearing15t axial load, the slips are still reliable.Based on the theory of metal cutting, build a bit cutting mechanics model, and make a calculation of single tooth cutting force by using MATLAB, provides the basis theory for the judgment of window bit’s cutting force.Based on the bending theory, established the mathematical model of the drill bit, and using MATLAB programming, gives the calculating results of examples, provide reference for the judgment of the mechanical process of sidetrack drilling.