As most of my country’s oil fields have entered the middle and late stages of crude oil extraction, the workover operations are becoming more and more arduous. In order to reduce the labor intensity of workers and increase the safety of operations, the research on automation of workover operations has become a hot research topic at present.
The tripping and tripping operation of the pipe string is the most common form of operation in the workover operation, and the elevator is one of the most critical devices in the tripping operation. At present, the operation of elevators in workover operations is mainly manual, with high labor intensity and low safety.
The automatic elevator can reduce the labor intensity of workers and increase the safety of operation, which has become the focus of research and development at home and abroad. At present, automatic elevators at home and abroad are mainly hydraulic flip-up elevators. According to the situation of workover operation equipment in my country, in order to save costs, based on manual elevators, a pneumatic Rotary automatic elevator.
The traditional manual elevator is operated completely by hand, so the labor intensity of operators is high and their safety is low. In this paper, an automatic turnover elevator was developed and the turnover mechanisms of key parts were optimized. Firstly, the parameters to be optimized were determined according to the requirement of geometric space. Then, the designed virtual model was introduced into the software Admas for kinematics and dynamics simulation. Based on the analysis, the optimal point was determined. Afterwards, an automatic turnover elevator was manufactured according to the optimal point. It is experimentally demonstrated that the elevator can be overturned well by virtue of the turnover mechanism and the error between the simulation result and the experimental result is smaller.
The automatic elevator is mainly composed of elevator body, loose-leaf, turning mechanism, loose-leaf switch mechanism, upper lock tongue switch mechanism and lower lock tongue switch mechanism, etc. The structure is shown in Figure 1. The loose-leaf switch mechanism is used to push the loose-leaf to close and open to realize the blocking and release of the oil pipe. The upper lock tongue switch mechanism and the lower lock tongue switch mechanism realize the locking and unlocking of the loose leaf and the elevator, ensuring the safety of the lifting oil pipe. The flipping mechanism realizes the flipping of the elevator, which is convenient for the elevator to jam the oil pipe. Brackets are used to protect and support the above mechanisms.
The purpose of the elevator flipping is to smoothly grab the oil pipes sent from the catwalk and other pipe pulling devices. Under different workover conditions, the inclination angle (the angle between the tubing and the horizontal plane) of the tubing that is sent to the tubing by the catwalk and other pulling and arranging devices generally ranges from 5° to 35°. When the axis of the elevator is parallel to the axis of the oil pipe and the elevator is in contact with the oil pipe, closing the elevator leaflet can smoothly realize the grabbing of the oil pipe. Due to the different inclination angles of the tubing sent by the catwalk and other pipe pulling devices, when grabbing the tubing, there are two ways to adjust the inclination angle of the elevator axis to be consistent with the inclination angle of the tubing axis.
(1) Adjusting the flip angle of the elevator through the detection and control system is consistent with the inclination angle of the oil pipe. This requires high requirements on the control system, and the corresponding cost will increase a lot compared to the manual elevator.
(2) According to the observation, when the wellhead operator flips the elevator, the inclination angle of the oil pipe sent by the catwalk and other pipe pulling devices is not exactly the same, and the elevator automatically matches the oil pipe under the action of gravity. According to the range of the inclination angle of the tubing sent by the catwalk and other pulling and arranging devices, we set the flip angle of the elevator to 75°. Under the action of the oil pipe, it is completely matched with the oil pipe, so that the grabbing of the oil pipe can be realized. This can not only realize the grabbing of the oil pipe, but also the control system is relatively simple, and the cost increase is not large compared with the manual elevator. By comparison, the second method is selected to realize the grabbing of the tubing.
According to the optimization results, an automatic elevator device is designed and manufactured. Under the action of the 994N cylinder force, the maximum flip angle of the elevator is 79.6°, and the maximum flip angle is reached in 0.22 seconds. At the maximum flip angle, the cylinder retracts a distance of 295.6 mm. The maximum turning angle error of the elevator is 3.16%, and the error between the simulation results and the experimental results is small and within the allowable range.
Experiments were carried out in the field environment: the flipping mechanism flips smoothly and quickly; the elevator door switch mechanism opens and closes stably and quickly; it can smoothly grasp the oil pipe with an angle of 0°~50° and a diameter of 73.02 series with the horizontal plane; Flexible, ensuring the safety of elevators. The operator is far away from the elevator remote control operation, which ensures the safety of the operator. The experiment has been running smoothly for several months.
On the basis of manual elevators, an automatic actuator is installed to realize the upgrade from manual elevators to automatic elevators. The application software optimizes the design of the turning mechanism of the automatic elevator. According to the optimization results, an automatic elevator device was made, and the flipping experiment was carried out. The simulation results were very close to the experimental results. Using Admas software to simulate and optimize the design model can reduce the production of experimental devices and save costs.