Manufacturing method of economical seamless oil well pipe for expansion pipe

Abstract

The invention provides an economical seamless oil well pipe for an expansion pipe and a manufacturing method thereof. The oil well pipe comprises the following chemical components in percentage by weight: 0.08 to 0.18 percent of C, 0.2 to 0.5 percent of Si, 0.6 to 1.7 percent of Mn, less than or equal to 0.012 percent of P, less than or equal to 0.005 percent of S, 0.04 to 0.15 percent of V, 0.01to 0.03 percent of Ti and the balance of Fe and inevitable impurities. A heat treatment process in the manufacturing method comprises the following steps of: incompletely quenching a hot-rolled seamless pipe, controlling the temperature of a heating furnace at 750 to 800 DEG C, keeping the temperature of the steel pipe in the range of 30 to 40 DEG C higher than Ac1 and 30 to 40 DEG C lower than Ac3 between the two phase regions of ferrite and austenite, performing calculation at the heat penetration speed of 1mm / min, preserving the heat of the oil well pipes for 10 to 60 min after the hot-rolled oil well pipes with different wall thicknesses reach the temperature of the furnace, and then cooling the oil well pipes at the speed of not higher than 0.2 DEG C per second. In the economical seamless oil well pipe and the manufacturing method thereof, the manufacturability and expandability performance of the steel pipe, the mechanical properties of the expanded steel pipe and the manufacturing cost are taken into account.

Description

technical field [0001] The invention belongs to the technical field of low-alloy steel, and in particular relates to a seamless steel pipe for expansion pipes and a manufacturing method thereof. The seamless steel pipe for expansion pipes is suitable for radial expansion in oil wells and gas wells to achieve the required borehole diameter. And the seamless steel pipe has excellent mechanical properties after diameter expansion. Background technique [0002] Expandable pipe technology is a practical technology developed in recent years. It uses a mechanical expansion device and is propelled by liquid pressure. When the expansion cone or mandrel is advanced, the downhole pipe is plastically deformed to expand the pipe diameter. Expansion tubes are divided into two categories: solid expansion tubes and slotted expansion tubes. The solid expansion tube is mainly used to: seal the lost zone and high-pressure water layer; seal the rupture zone; repair the damaged casing and plug ...

AI Technical Summary

Problems solved by technology

For example, the Japanese patent with the application number PCT / JP2006 / 312080 only pointed out that the oil well pipe invented by it has excellent impact performance after pipe expansion, and did not mention the properties such as uniform elongation and yield strength ratio which are crucial to the expansion and deformation performance of steel pipes ; and the Chinese patent application number 200410019863.X does not mention the impact performance of the oil well pipe after pipe expansion; while the U.S. patent No. 7225868 and the U.S. patent application No. 11790874 do not mention the expansion deformation of the steel pipe Uniform elongation, yield strength ratio, and no introduction to the impact performance of oil well pipe after pipe expansion

And application number is the Japanese patent of PCT / JP2008 / 054747, application number is the Chinese patent of 200610112983.3, the U.S. patent that the patent number is 6851455 all uses high alloy material as the raw material of expansion tube, and the alloy cost of raw material and manufacturing cost are higher, and raw material It is very difficult to implement the manufacturing process in steel mills, and it also loses the original intention of cost-saving expansion tube drilling technology

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