A kind of j55 steel grade large expansion rate welded pipe and its preparation method

Abstract

The invention discloses a J55 steel grade welded tube with a high expansion rate, and a preparation method thereof. The chemical components of the welded tube with the high expansion rate comprise, by mass, 0.03%-0.12% of C, 0.15%-0.35% of Si, 2.5%-5.5% of Mn, 0.10%-0.50% of Mo, 0.01%-0.05% of V, no more than 0.01% of S, no more than 0.015% of P and the balance Fe and unavoidable impurities. The preparation method comprises the steps that the raw materials containing the chemical components are smelted into plate blanks, and then the plate blanks are rolled into coiled plates; the coiled plates are made into tube blanks through HFW and weld online heat treatment, then the tube blanks are thermo-mechanically rolled overall, and the thermo-mechanically rolled tube blanks are subjected to online controlled cooling treatment and gamma + alpha two-phase region insulation treatment to obtain the J55 steel grade welded tube with the high expansion rate finally; the method ensures that the longitudinal yield strength of the tube is 379-552 MPa, the tensile strength is more than 517 MPa, and the elongation is more than 15% after radial expansion deformation of no less than 20%; and the performances of the tube after expansion are effectively ensured to meet the API Spec 5CT-J55 standard requirements.

Description

Technical field: [0001] The invention belongs to the technical field of welded pipes, in particular to a J55 steel grade welded pipe with a large expansion rate and a preparation method thereof. Background technique: [0002] The single wellbore technology is also called "equal diameter drilling", which is to abandon the original casing sequence, use the technical characteristics of expandable pipes, replace the casing with expandable pipes, and run multiple stages of the same size expandable pipes in the wellbore And cementing, not only can effectively solve the problem of small liner size caused by the tapered well depth structure, which affects oil production capacity, but also can isolate complex formations without sacrificing the diameter of the wellbore, reducing the limit of the wellbore level The frictional resistance of displacement increases the drilling speed and greatly reduces the drilling and completion time. Expandable pipe products are divided into two types...

AI Technical Summary

Problems solved by technology

J55 steel grade is an important oil casing steel grade in the American API Spec 5CT standard. It consumes a lot in the field of oil and gas exploration and development in my country. However, there is no J55 steel grade high expansion rate expandable pipe product with mature technology in China.