A high-strength anti-collapse oil casing string and its manufacturing method

Abstract

The invention discloses a high-strength anti-collapsing petroleum casing column. The casing column comprises the following chemical elements in percentage by mass: 0.24-0.30 percent of C, 0.9-1.3 percent of Mn, 0.25-0.50 percent of Si, 0.9-1.3 percent of Cr, 0.6-0.8 percent of Mo, 0.06-0.10 percent of V, 0.01-0.03 percent of Al, 0.02-0.05 percent of Nb, 0-0.03 percent of Zr, less than 0.004 percent of B, less than 0.03 percent of Ti, less than 0.015 percent of P, less than 0.010 percent of S, 0.001-0.006 percent of Ca, and the balance of Fe and inevitable impurities, wherein Ca / S ratio is more than 1; the external diameter size Phi of the casing column is 141.3 mm to 142.7 mm; and the wall thickness of the casing column is 10.7 mm to 12.9 mm. Correspondingly, the invention further provides a manufacturing method of the casing column.

Description

technical field [0001] The invention relates to an oil casing pipe string and a manufacturing method thereof, in particular to a collapse-resistant oil casing pipe string and a manufacturing method thereof. Background technique [0002] Zhongyuan Oilfield has special geological conditions. Most oil wells need to pass through salt rock layers, mudstone layers, and salt-gypsum layers. The in-situ stress is as high as 120MPa. 168MPa. In addition, because the well section in the salt layer is very unstable and has plastic creep, it will do great harm to the drilling construction and the casing after completion. Generally speaking, the external extrusion force and maximum stress of the oil casing increase with the increase of the thickness and depth of the salt layer. The dissolution of the salt-gypsum layer causes the wellbore to expand, forming a karst cave, and the casing forms a compression bar to support the pressure of the overlying strata. The external extrusion force w...

AI Technical Summary

Problems solved by technology

[0005] (2) Due to the high rigidity of the thick-walled casing, the choice of the kickoff point must be cautious, otherwise it may directly lead to the difficulty of going into the well;

[0006] (3) Most of the development wells currently used are directional wells with a large well inclination angle, which increases the possibility of encountering resistance when the special casing is run into the well. For this reason, each thick-walled casing needs to be installed when running into the well casing centralizer