How to achieve ultra-long stroke in oil pumping？
Worldwide, as conventional oil resources are depleted, the reciprocating sucker rod pumping systems are recognized as the most widely applied mean of artificial lift system for onshore wells. The popularity of this system is attributed to its durability, simplicity, and flexibility. The advanced technologies in surface and downhole equipment overcome many of the old problems, such as; producing difficult fluids (high gas and/or sand, corrosive fluids and heavy crude) and producing unconventional wells.
The necessity to maximize production and produce difficult fluids in higher economic efficiencies for rod pumped wells has created a high demand for ultra-long stroke lengths and high capacity units.
In the process of extracting oil from the stratum, mechanical equipment is used to lift the crude oil in the well to the ground, and the sucker rod pump is the main oil extraction equipment. The sucker rod pump is a special form of reciprocating pump. The power is transmitted from the ground to the downhole through the sucker rod, so that the plunger of the sucker rod pump moves up and down to lift the crude oil in the oil well along the tubing to the ground. As the depth increases, the stroke of the sucker rod pump is getting longer and longer.
What needs to be explained is that the plunger of the sucker rod pump moves up and down in the barrel structure for one stroke at a time. In order to achieve an ultra-long stroke, a long barrel structure is required.
The ultra-long-stroke sucker rod pump in the prior art uses a long barrel structure assembly. The total length of the barrel structure assembly is greater than 50 meters, and it is composed of more than 5 pump barrel structures, each of which is greater than or equal to 10 meters, the pump barrel structure is connected by a pump barrel structure coupling threaded connection to ensure that the inner diameter concentricity error of every two pump barrel structures is not greater than 0.02mm, and the length of the plunger sealing surface is greater than or equal to 1.5 meters, The matching clearance between plunger and pump barrel structure is level 1.
However, the sucker rod pump in the prior art has high requirements for the entire pump barrel structure and plunger, and the production process of the sucker rod pump is complicated. Specifically, the sucker rod pump in the prior art has high requirements on the structure material of the pump barrel itself.
The pump barrel structure is repeatedly rolled and drawn, the inner and outer walls of the pump barrel structure have equal wall thickness, the straightness of the pump barrel structure is 0.05mm/m, and the inner and outer diameter coaxiality does not exceed 0.1mm.
Secondly, the processing process of the pump in the prior art is complicated , The structure of each pump barrel shall be subjected to four straightening processes (cutting, chrome plating, thread processing, assembly of adjacent pump barrel structures). Each shift shall correct the clamping device of the honing machine, and use a special 6-meter expansion center for special machine tools. Die positioning processing thread, thread processing adopts the workpiece non-rotating process, and the pump barrel structure is connected with straight threads.
The pump barrel structure must be installed on the spot with a friction clamp tool, which is more troublesome for special personnel to operate. The sucker rod pump has the problems of difficulty in preparation and high cost in the actual production and installation process.
Our specially designed ultra-long-stroke sucker rod pump, which includes a pump barrel assembly and a plunger assembly; the plunger assembly is located in the pumping passage of the pump barrel assembly, and the plunger assembly runs along the pump barrel assembly. The pumping channel moves in order to use the movement of the plunger assembly to lift the crude oil in the oil well to the ground along the tubing. And the plunger assembly includes a plunger joint, the first plunger and the second plunger.
The first plunger and the second plunger are connected by a plunger joint. The plunger joint can adjust the relative deflection between the first plunger and the second plunger. In actual operation, when the pumping channel of pump barrel assembly has a deviation angle, and when the first plunger and the second plunger move to the position corresponding to the deviation angle, due to the existence of the plunger joint, the movement deviation between the first plunger and the second plunger will be automatically adjusted. which enables the first plunger and the second plunger to move along the specific shape of the pumping passage of the pump barrel assembly.
Therefore, the pumping passage of the pump barrel assembly does not need to meet the inner and outer diameter coaxial requirement that the degree does not exceed 0.1mm, which reduces the manufacturing and installation requirements of the pump barrel assembly, and alleviates the technical problems of the sucker rod pump manufacturing difficulties and high cost existing in the prior art.