Research On The Key Technology Of Casing Pipe Cutting And Retrieving Combined Tool

According to the provisions of relevant state departments,in offshore oil drilling operation,before the platform not apply for the wellhead retention is shifted,the wellhead installation must be cleared from the seabed 4 meters.This requires that cut and retrieve casing pipe from the inside to the outside in the appropriate well depth,and recover the whole wellhead system and seal the wellhead.This process is called abandoned wells,and it is the final set of exploratory oil well processes.The first step of abandoned wells process is cutting and retrieving production casing and intermediate casing hanging in the wellhead,the most conventional is cutting and retrieving 95/8-in and 133/8-in casing pipe.In our country,cutting and retrieving operations usually adopt the traditional way or carried out by foreign companies.With the increasing of operating depth and change of drilling cost composition,daily rates of platform operation increase,so,improving the operation efficiency become the key to reduce the cost of platform operation.Thus,a combined tool of cutting and retrieving casing pipe emerged as the times require.And,the combined tool can not only be applied to the abandoned wells process,also play an important role in drilling additional wells,adjustment wells and sidetracking operations from the old one in oilfield.Therefore,in order to reduce offshore oil and gas production cost,promote the development of the offshore oil and gas,break the monopoly of foreign technology,and fill the domestic blank,the research of combined tool is imminent.This paper analyses the existing deep water wellhead and wellbore structure in the foreign and domestic hot zone.Study the existing way of the mechanical casing pipe in the well abandonment,workover and sidetracking.Puts forward the functional and technical requirements related to the design of combined tool for disposable cutting and recover 13 3/8?intermediate casing in the wellhead.The overall scheme of cutting and retrieving casing tools is determined to be combined tool of the lifting spear and hydraulic cutter.After the design of combination tool was completed,aiming to the parts stress in the different operation condition,adopt the Ansys software to analyze the strength and reliability,evaluate the parts design rationality.On the basis of this,the influence of vibration on the operation stability is analyzed by the simulation of computer software on casing cutting process.Obtain the selection range of the drill pipe rotation speed by the calculation of natural frequencies.Discuss the method of reducing the resonance phenomenon and enhancing system stability to achieve the purpose of cutting smoothly.