An Evaluation Method of Snubbing Units in China

Abstract Since the popularizing of snubbing technique in China, a number of new types of snubbing units appeared in oil fields. Without new industrial standards, it was difficult for users to choose the exactly suitable units to fit into their conditions. Consequently, most units were inefficient and accompanied high maintenance cost. It is urgent to draft a rational selection reference for solving above problems. This paper introduces an evaluation method on varied versatile snubbing units except those special units, including classification, rationales, characteristics, advantages & disadvantages, and costs. Based on investigation, by comparing rationales and analyzing structure characteristics, the snubbing units can be classified into several types. Advantages & disadvantages provide the comparisons of mobility, integration, theoretical efficiency and well site requirements. The cost evaluation which is composed of acquisition cost, operation cost and maintenance cost provides an economic effectiveness ranking among different types. According to these five aspects' comparisons, the rated ranges of use are provided. According to this evaluation method, snubbing units in China are divided into 2 types, separated type and independent type, and subdivided into 5 subtypes. Normal rig-assistant type and single hydraulic power rig-assistant type belong to separated type. Rig-less type, vehicle-mounted integration type and hydraulic energy-storing service rig type belong to independent type. Each subtype associates with specific rationale and structure characteristics, and it is easy to identify by users. Furthermore, each subtype has unique level of mobility, integration, theoretical efficiency and well site requirements, which means that users have more accurate specifications to choose ideal snubbing units for their certain conditions. What is more, there is a cost evaluation to balance their budgets or anticipations before purchasing. For example, in the northeast of China, the well depth is average and it is a plain area. According to this method, mobility should be the main consideration in all matters. Therefore, vehicle-mounted integration type is highly recommended to the users from that area. However, in the southwest of China, because of the mountains, separated type is better. This selection reference is very convenient and effective for Chinese users. The research result in this paper helps users, mainly, producers and managers to acquaint snubbing units' situations in China and to take advantage of that for better work performance. It promotes standardization of snubbing industry and has formed a new industrial standard. In addition, this result potentially improves the rate of capacity utilization which is particularly beneficial to petroleum industry.