A subsurface sucker rod pump, also known as a tubing pump, is a type of downhole pump used for artificial lift in oil production. This pump is characterized by its installation method, where the outer barrel, bushing, and intake valve are preassembled at the surface and lowered into the well with the tubing. The piston, which contains the discharge valve, is then run into the pump through the tubing using the sucker rod.
The bushing is manufactured in multiple sections and inserted inside the outer barrel. The piston, made from seamless steel tubing, is a hollow cylindrical body with a smooth outer surface and annular grooves. These grooves help collect sand particles entering the clearance between the piston and bushing, preventing wear and reducing friction by storing oil for lubrication.
During pump retrieval and inspection, the oil inside the tubing must be drained. This can be achieved by using a retrievable intake valve (fixed valve). The sucker rod string is lowered to latch onto the retrieval head of the intake valve, allowing it to be pulled out. However, this design reduces pump efficiency due to increased clearance volume and susceptibility to gas interference.
In modern applications, most tubing pump installations utilize a drain valve at the lower section of the tubing to release oil before retrieval. For large-diameter pumps, where the piston is too wide to pass through the tubing, an alternative method is employed: the piston is run into the well with the tubing, and the sucker rod string is later inserted to connect with the piston using a disconnecting device.
