Petroleum casing is a steel pipe used to support the well wall of oil and gas Wells , so as to guarantee the normal operation of the whole well after the drilling process and completion . Each well USES several layers of casing depending on drilling depth and geology . Cement cementing should be used after casing running . It is different from oil pipe and drill pipe , and can not be reused . It is a disposable mate – rial . Therefore , the consumption of casing accounts for more than 70% of all oil well pipes . According to the strength of steel itself , the casing can be divided into different steel levels,namely,J55, K55, N80, L80, C90, T95, P110, Q125, V150,etc.Different well conditions and depths,different grades of steel are used.
