Development of PTs 35-3.5-0.5/2.5 chain drive mounted above wellhead

This work presents a novel design of an open-type chain drive for a sucker-rod pumping unit with a 3.5-m length stroke and a 35 kN load capacity. This chain drive is mounted directly above the well head, and is an optimal solution for rod-lift production of low-volume wells. For the chain drive body, double tee profiles with parallel faces are used, which serve as both a support structure and balance weight guides. The paper presents technical characteristics of the new-design chain drive in comparison to PTs 30 model chain drive developed by the Bugulma Mechanical Plant, as well as a case study. The authors analyze technical solutions and consider ways to improve the chain drive design. It is recommended to reduce weight of the chain body, use a screw-pile foundation, and dismountable guides made of high-grade steel.
Materials and methods
GOST 26020-83 I-beam No. 55 with Parallel Flange Edges, cylindrical triple reduction gearbox 1TsZU-160-100-31-U1, 2.2-kW explosion-proof motor 4ВР90L4 with shaft speed of 1430 min-1, roller chain 1NP 50.8-145 with breaking strength of 263 kN, roller chains 1NP 31.75-192 with breaking strength 100 kN. Theoretical substantiation of technical characteristics and operational advantages, design and construction of test specimen, filed testing, analysis of test results.
Results
A new chain drive was designed to enable lifting capacity of as high as 35 kN, stroke length of 3.5 m and oscillation frequency from 0.5 to 2.5 min-1. Field tests confi both serviceability of the drive and its compliance with specifi ation requirements. At the same time, some challenges during wellhead operations were revealed. These were associated with limited-access conditions within drive sub-frame.
Conclusions
Lessons learned from development, construction and fi d testing of PTs 35-3.5-0.5/2.5 chain drive test specimen brought forth further design improvements. Particularly, the housing of the drive may be implemented as an independent lightweight metal structure while replaceable, space-adjustable guideways may be made of mechanically upgraded steel to ensure high quality of the surface. Appropriate drive base plates are screw piles screwed into the ground up to fi soil level and below soil frost depth in winter.