135 steel-level drill rod connector and heat treatment process thereof

Abstract

The invention relates to a 135 steel-level drill rod connector and a heat treatment process thereof. The drill rod connector comprises the following components in percentage by weight: 0.25-0.32 percent of C, 0.30 percent of or less Si, 0.35-0.80 percent of Mn, 0.015 percent of or less P, 0.008 percent of or less S, 0.15-0.80 percent of Mo, 0.00-1.00 percent of Ni, 0.90-1.50 percent of Cr, 0.30 percent of or less Al, 0.05 percent of or less Nb, 0.10 percent of or less V and the balance of Fe and unavoidable trace elements. The heat treatment process comprises the steps of: heating a roughly processed connector blank to 920-960 DEG C from the room temperature, preserving heat for 0.5-1.5 hours, putting the connector blank into a high-grade oil base quenching medium at 30-50 DEG C, fully cooling the connector blank, then heating the connector blank to 550- 620 DEG C from the room temperature for 50-70 minutes, preserving heat for 1.5-2.5 hours, and then discharging the connector. After heat treatment, the mechanical performances are as follows: the yield strength is 140-160 Ksi (965-1100 MPa), the elongation percentage is larger than or equal to 17 percent, the drill rod connector is longitudinal and is at 20 DEG C below zero and has full size, and the charpy impact energy is higher than or equal to 100 Joules.

Description

technical field [0001] The invention relates to a high-strength and high-toughness drill pipe joint used in drilling, especially deep wells and ultra-deep wells, and a heat treatment process thereof. The joint of the invention is 135 steel grade and belongs to the technical field of oil and gas drilling. Background technique [0002] With the development of drilling technology and the gradual reduction of shallow easy-to-exploit oil and gas layers, the drilling depth is increasing. In recent years, a large number of 7000-8000m ultra-deep wells have been drilled in my country, and my country's offshore drilling is also gradually moving towards deep-sea development. In order to be able to operate under such harsh well conditions, the oil field hopes to provide high-strength and high-toughness drill pipes. However, the currently commonly used drill pipes of the highest steel grade S-135 that meet the requirements of the American Petroleum Institute (API) cannot meet its require...

AI Technical Summary

Problems solved by technology

[0003] The test results show that the commonly used joint material 37CrMnMo, when its yield strength is 140-160Ksi (965-1100MPa), the impact energy is often only about 50-60J at -20°C, which cannot meet the performance requirements of 135 steel grade drill pipe joints

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