Design And Research Of Down-hole Blowout Preventer In Work-over Operation

Oil and gas are important energy and strategic resources to guarantee the sustainable development of the national economy,the stability of social life and the security of country.Well and well tools will have a series of problems in the late stage of oilfield development which need professional work-over team to solve.Safety,rapid and high efficiency are the goals that are pursued continuously in the process of well repairing in oil fields,especially the safety is the most important.During work-over process,blowout accidents will occur if the bottom hole pressure is far greater than the pressure in the well,especially for oil wells with high flowing capacity,high oil-gas ratio or operated with pressureless measures.Once a blowout accident happens not only will the oilfield lose a lot of property and resources,but more importantly,the work-over crew on the well is also facing life risk.Therefore,the work of preventing blowouts during well repair operations is the most important task for the down-hole operations.This object aim to research the down-hole blowout prevention technology for workover operations and design a set of down-hole blowout prevention tools that are suitable for work-over operations.In this paper,the mechanism of blowout in well work-over are researched and the design requirements of down-hole blowout preventer are confirmed.The design parameters of downhole blowout preventer are determined according to the wellbore parameter of a well and the construction work-over parameters.Several kinds of down-hole blowout preventer solutions are conceived,through comparative analysis.A down-hole mechanical blowout preventer designed to achieve simultaneous anti-spraying in the annular space and throttling in the pipe string.The designed anchoring tool can realize the anchoring of any position of the pipe string.At the same time,the three-dimensional model of the down-hole blowout preventer and its supporting anchoring tools is established,and the assembly engineering drawing is drawn.The critical part of the tool was analyzed and checked.Sealing performance of the sealing unit,throttling performance of the blowout preventer,and anchoring performance of the anchoring tool were analyzed.