P110 casing is suitable for cementing deep Wells where the tensile strength is not up to the requirement due to the use of round casing, and only one section is used at the wellhead.  This paper calculates how much special connection casing can be put into the wellhead to achieve the purpose of saving, and points out the application range of using the special connection casing for the whole downhole well cementing and the economic benefit obtained by using the special connection casing.  

The joint types and structures of TM, SE-EF, NK3SB, NSCC, SEC, VAM, BDS, FOX and so on are analyzed.  China has independent intellectual property rights, can form a Chinese brand effect of special oil pipe development direction.  

There have been many corrosion failures of 13Cr tubing in domestic oil fields, and the corrosion sites are mainly in tubing joints. The basic corrosion characteristics of P110 oil casing are pitting corrosion.  In May 2004, a batch of special 13Cr tubing was run into an oil well. In June 2011, when the well was repaired, a large number of corroded pits were found in the shoulder wall of the outer thread joint and the part where the chamfer disappeared, and the depth of the tubing was 5001.85m.  In this paper, taking the well as an example, the price of 13Cr /P110 oil casing/special connection casing is higher by means of physical and chemical test and microscopic analysis.