Tension-Torque Analysis Of Pipe String During Liner Cementing

With the continual exploitation of oil and natural gas, exceptional wells are increasing, such as, deep, ultra-deep, high angle deviate, SH & SG wells, liner cementing is the most commonly used method to improve the cementing quality of deep and special wells. However, because of insufficient theoretical knowledge on liner cementing, it is operated mostly by virtue of experience, and a lack of the quality of science, especially the lack of mechanical analysis of liner and drill string. Therefore, it causes frequent occurrence of serious downhole accidents, for example, un-hanger, liner twist-off, cementing disqualification, and even results in the full hole out of use, which cause serious economic losses. Therefore, mechanical analysis of the process of running casing and cementing is of important and practical significance.The so-called liner cementing, is the process of sending a section of casing for designed well location via the means of sending drill pipe and the hanger, hangering which at the design position of the rear suspension in the upper casing, pulling out the hanger center tube after back off and cementing, circulating out of excess cement, and finally removing drill pipe. This paper aims to be a more detailed and accurate consideration for the various factors, and a more detailed and precise mechanical analysis of the columns on the various stages of cementing.First of all, the home and abroad research present situation that the well cementation technique was rund by the tail is Surveyed and studied. On condition that the slurry viscosity and the shear force is constant, according to basic equations of mechanics of the rod string of professer Li Zifeng, the tension-torque model of directional well drilling liner and running drill string under various conditions is established. Secondly, the role of oil well cement hydration changes as time is analyzed and summarized. Thirdly, based on cement time-variant, the model is amended and the necessity of continuing rotating tail pipes after the completion of the replacement is pointed out. At last, based on the above theory and the field construction needs, cementing engineering analysis software is developed by VB2008, which is of great significance for guiding the field practice.