What Sucker Rod Pump is suitable for Steam injection heavy oil wells？
Steam injection sucker rod pump
Steam huff and puff is a method of injecting a certain amount of steam into the oil well, shutting it in for a period of time, and then opening the well to produce heavy oil after the thermal energy of the steam diffuses into the oil layer. The process of steam huff and puff operation can be divided into three stages, namely steam injection, well simmering, and recovery.
The steam huff and puff method is the most commonly used method in heavy oil production, and it is also the best thermal recovery method for industrial applications. Steam stimulation is also called steam stimulation or cyclic steam injection.
The outstanding feature of heavy oil is that it is very sensitive to temperature, which can be seen on the viscosity-temperature curve. After injecting 250-350℃ high-temperature and high-pressure steam and hot water into the oil layer, the oil layer and crude oil within a considerable distance near the well are heated.
The viscosity of crude oil in the heating zone formed in this way will be reduced from thousands to tens of thousands of milliPascals to a few milliPascals.
The resistance of crude oil flowing to the bottom of the well is greatly reduced, and the flow coefficient (Kh/μ) increases by several tens of times. The output will inevitably increase many times.
Super heavy oil injection and production integrated downhole pump are suitable for thermal recovery of super heavy oil in single well steam huff and puff.
One string operation can realize two major steps of steam injection and oil production, which can be used together with insulated tubing and hollow sucker rod to achieve high efficiency.
Cyclic steam stimulation is an effective way to recover heavy oil with simple operation and low risk. Each well can be operated for five to eight cycles, with oil recovery rates of up to 3% to 8% and oil recovery rates of 10% to 20%, resulting in the loss of some recoverable reserves. The effective heating radius of steam stimulation is less than 30m.
At present, the sucker rod pump sued for steam injection heavy oil wells is a single plunger pump. It adopts the structure of grooving on the pump barrel to realize steam injection and pumping. There is no need to use a work rack when steam injection and the injection and pumping conversion is simple.
When steam injection is required, simply lower the plunger to expose the steam injection hole, and then steam injection can be performed. When pumping oil, lift the plunger to work normally. However, when steam is injected, the pump barrel above the steam injection hole is affected by high-temperature steam which is easy to scaling or damage.
There is a gap between the lower plunger and the extension tube. The steam in the string enters the space between the lower plunger and the extension tube from the standing valve. It makes the bottom of the lower plunger corroded which causing the sucker rod pump not to work normally.
In order to improve the efficiency of heavy oil wells, SanJack has developed a double plunger steam injection sucker rod pump with simple structure and convenient operation to prevent pump barrel scaling and plunger damage. This pump is composed of plunger assembly, pump barrel assembly, standing valve assembly, and so on. The structure diagram is as follows:
|1||Plunger Assembly||7||Pumping Plunger|
|2||Sealing Plunger Assembly||8||Pumping Plunger Assembly|
|3||Barrel Assembly||9||Lower Joint|
|5||Sheath||11||Standing valve assembly|
|6||Hole||12||Standing valve ball|
There is a sealing plunger on the upper part of the pumping plunger assembly. The pumping plunger assembly and the sealing plunger are connected by a connecting joint to form a plunger assembly. The lower part of the pumping plunger is equipped with a lower joint that pressed the standing valve ball.
The pump barrel has a plurality of steam injection holes, and the pump barrel is equipped with a sheath outside the steam injection hole. When injecting steam, lower the plunger assembly so that the lower joint compresses the standing valve ball. At this time, the annular chamber formed between the connection joint and the pump barrel is exactly at the same position as the steam injection hole on the pump barrel.
Steam enters the casing directly from the steam injection hole of the pump barrel through the sealing plunger and is injected into the bottom layer, which prevents the pump barrel above the steam injection hole from being affected by high temperature and high-pressure steam and causing scale and damage.
The steam that enters the casing cannot enter the annular space of the pumping plunger and the extension tube due to the lower joint pressing against the standing valve ball, which prevents damage to the pumping plunger.
The outer sheath of the steam injection hole can prevent the high temperature and high-pressure steam from puncturing the casing and affecting the normal operation of the pump. When the steam injection is completed, the plunger assembly is lifted up, so that the pumping plunger will always normally seal the steam injection hole of the pump barrel during the pumping process, and the pump can work normally.