Research and Practice of Rotating Technique for Liner Hanger

Abstract

Rotating liner hanger cementing technique plays a significant role in solving complex problems of drilling op- erations. The technique can eliminate resistance of liner running, and greatly improve the efficiency of cement slurry dis- placement while pumping cement slurry. In this paper, a set of rotating liner tool composed of rotating liner hanger, hy- draulic release tool, rotating cementing head and low-drag spiral centralizer has been developed. And the sealed bearing is researched, which is the key part of rotating liner hanger, and can improve bearing load and life by optimizing its material, structure and processing. Oilfield tests show the rotating liner hanger can function well in terms of rotating, setting and re- leasing. This paper describes the design method, structure principle, characteristics and oilfield application cases of the tool. The rotating liner hanger is driven by ground power such as top drive, rotary table or power tong, then transfers torque to liner, and makes it swivel while running, cementing and circulating drilling fluid after setting. So, rotating liner hanger makes the liner run into hole bottom smoothly, and cementing slurry displaces drilling fluid fully. Then dis- placement efficiency and bonding quality are improved (1). Compared with regular liner cementing technology, rotat- ing liner hanger has the following advantages. Firstly, liner is easy to run in the expected position. Secondly, displace- ment efficiency and cementing quality can be improved. Thirdly, it is helpful to resolve cementing problems in wells with smaller annular clearance. Fourthly, it can improve dis- placement efficiency caused by casing eccentricity in direc- tional wells and prevent annular channeling from forming as well (2). This paper studies the key techniques of rotating liner hanger including hanging mechanism, setting tool, and bear- ing, etc. Finite element analysis is used to compute the load capacity of hanging device and setting tool, and load curve of liner hanger is obtained. According to the calculation re- sults, releasing scheme and parameters of running tool are designed and developed. Results of simulated running-into- hole experiments and field tests show that load capacity of new liner hanger is largely increased, and cementing quality is improved obviously. The detailed introduction is given hereinafter.