Tubular pump

A tubular pump, also known as a tubing pump, is characterized by assembling the outer cylinder, liner, and suction valve on the ground and connecting them to the lower part of the tubing. It is first lowered into the well, and then the piston with a discharge valve is lowered into the pump through the tubing using a sucker rod.

The lining is processed into several sections from the material and inserted into the inner part of the outer cylinder. The piston is a hollow cylinder made of seamless steel pipe, with a smooth outer surface and circular grooves. Its function is to gather sand particles entering the gap between the piston and the liner in the grooves, preventing sand particles from wearing the piston and liner. The oil stored in the grooves also lubricates the surface of the piston.

When checking and starting the pump, in order to drain the oil in the oil pipe, a salvageable suction valve (fixed valve) can be used. By lowering the rod column, the buckle at the lower end of the piston can bite the salvaging head of the suction valve and lift it out. However, due to the suction valve fishing head occupying the internal space of the pump, this type of pump has a large anti impact distance and clearance volume, which is easily affected by gas and reduces pump efficiency. At present, most wells with tubular pumps are equipped with oil drains at the bottom of the tubing, which are opened to remove oil from the tubing. In a well with a large pump, due to the diameter of the piston being larger than the inner diameter of the oil pipe, it cannot be inserted through the oil pipe. The method used is to first lower the piston into the well with the oil pipe, and then lower the pumping rod string. A device called a disconnect device is used to connect with the piston in the pump.

The tubular pump has a simple structure, low cost, and allows for a larger pump diameter to be lowered under the same oil pipe diameter compared to the rod pump, resulting in a larger displacement. However, when inspecting the pump, the tubing must be removed and the workload of well repair is large, so it is suitable for wells with low pump depth and high production.

Rod pump

Rod type oil well pump, also known as an insertion pump, is characterized by a fixed top fixed rod pump with inner and outer working barrels. The upper end of the outer working barrel is equipped with a vertebral seat and a clamp spring (the position of the clamp spring is the depth of the lower pump). When the pump is lowered, the outer working barrel is first lowered into the well along with the oil pipe, and then the inner working barrel with a liner and piston is connected to the lower end of the sucker rod and inserted into the outer working barrel, which is fixed by the clamp spring. In addition, there are fixed bottom fixed rod pumps with fixed points at the bottom of the pump barrel, as well as movable bottom fixed rod pumps that fix the piston at the bottom and drive the pump barrel to reciprocate up and down by the pumping rod.

When inspecting the pump, it is not necessary to pull out the oil pipe, but to pull out the inner working cylinder through the oil rod. Rod pump inspection is convenient, but the structure is complex and the manufacturing cost is high. The pump diameter allowed to be lowered under the same oil pipe diameter is smaller than that of tube pump, making it suitable for oil wells with larger pump depth and smaller production capacity.

At present, conventional oil well pumps have the disadvantages of high processing requirements for metal pistons and bushings, inconvenient manufacturing, and easy wear and tear.