Numerical Analysis And Reliability Of Petroleum-Drawworks

Drawworks have been widely applied to oilfield equipments such as drilling rigs, well service rigs and oil extraction cars. As the main gearing machinery, whether they can operate securely and stably is extremely important to the whole petroleum industry. How to improve their structure, increase their efficiency and prolong their lifespan, especially under tough working situations, has always been the study focus of researchers. Usually using manual computation, present petroleum drawworks design process exists such flaws as excess work load, low precision and efficiency, etc. Thus it is of great significance to develop a special design and analysis software.This paper systematically reviewed the history of drawworks application in oilfields and the progress of its design and analysis theory, and elucidated the main design theory about the roller, brake system and gearing system of drawworks. Basing on this, a new design and analysis software has been developed on Visual Basic 6.0. The software consists of three main modules (i.e. roller module, brake system module and gearing system module) and two auxiliary ones (i.e. design module of the general parameter and design module of the other component parts). These modules can be tranferred to help finishing the following tasks: selection and calculation of the general parameter, model design and analysis of the roller, the main and assistant brake, and the gear and chain transimission, and design and calculation of other main component parts such as shaft, bearing, connecting device and bolt. The tranferring progress is simple, precise and fast, and thus can greatly improve the work efficiency of the designer.Taking XJC12 well service rig as a calculation example, this paper studied the change rules of its rollers'structural statics under different work situations on ANSYS Finite Element Software, and accordingly analyzed the global reliability of the rollers. Results showed that the roller shaft, shell and baffle plate were vulnerable component parts, and reliability of each was over 99.5 percent, and global reliability of roller was up to 99.07 percent, which suggested that the structure of roller was quite safe and totally fitted the demands of its design codes.