Research and Application of New Type Hydraulic Submersible Pump

The superior performance of the pump. At present, this type of pump is still in the research stage in China. It is introduced that this type of pump has a definite reference value for our technical personnel.

In the rodless oil recovery system, the domestic main oil extraction equipment is an electric submersible centrifugal pump. The electric submersible centrifugal pump has certain advantages in the case of deep pumping and moderate liquid production, but it does not contain gas, high well temperature, and liquid production. The deficiencies in the stability and other special cases are more obvious. For example, the maximum allowable gas-liquid volume percentage (GVF) at the suction port of an electric submersible centrifugal pump is 30% to 40%. If this range is exceeded, the centrifugal resistance of the centrifugal pump will be caused. Can not run, electric submersible centrifugal pump adaptable well temperature is usually within 150 C, after this temperature, the life of the insulation material in the power cable and motor will drop sharply; the range of adaptation of electric submersible centrifugal pump is also rated displacement Within ±15% of the time, it may not be able to adapt to the changing production conditions of most oil wells in the middle and later stages of the oil field.

It is based on the above reasons that the UK's Clyde Pump Company has been developing the HSP hydraulic submersible pump since the 1990s. 1. This new type of pump drives the underground turbine to rotate by injecting the power fluid into the underground oil production equipment through the ground water injection pump. Drive the centrifugal pump lifting liquid on the same shaft. Because there is no downhole submersible motor and power cable in the system design, its adaptable well temperature can reach more than 200C. It can also change the pump's rotation speed by adjusting the size of the injection pump's injected fluid to adapt to the change in well productivity. Case. In addition, for gas wells with high gas content, its gas processing capacity can reach 60% to 80% (GVF), and its performance is very superior.

In recent years, the new pump has been continuously put into use in the CaptainA and CaptainB areas, and its use has proven to be very effective, fully validating this type of technical analysis. The new hydraulic submersible pump is mainly composed of a ground section and a downhole section, as shown. The ground section includes the electric motor, water injection pump, separation tank, filter, and ground pipeline. The downhole section includes tubing, cross-flow passage joints, turbines, centrifugal pumps, packers, and tail pipes.

A schematic diagram of a new type of hydraulic submersible pump (the arrow is the flow direction of the liquid) 1 - a separation tank; 2 - filter; 3 - electric motor; 4 - injection pump; 5 - hanger; 6 - tubing; 7 - turbine; 8 - cross-flow passage joint; 9-centrifugal pump; 10-packer; 11-tail tube.

The injection pump is usually a vane-type pump wheel structure. It is connected to the wellhead through the ground pipeline. The hanger is installed at the wellhead. The upper end is connected with the ground pipeline and the lower end is connected with the downhole oil pipeline. Downhole turbines, centrifugal pumps and other units are completely threaded, and there are no coupling components such as couplings. The installation is simple and reliable. The turbine is at the upper end of the unit, the centrifugal pump is at the lower end, and the tail pipe is installed at the lower end of the centrifugal pump. The packer on the outside of the tail pipe seals the annular space inside the tail pipe and the casing.

The internal structure of the hydraulic submersible pump is shown in the figure. The direction indicated by the arrow in the figure is the flow direction of the liquid. The turbine and the centrifugal pump leaf guide wheel are mounted on the same shaft. The turbine is in the upper part of the shaft and the centrifugal pump leaf guide wheel is in the lower part of the shaft. The thrust bearing is installed in the middle of the shaft to play the role of bearing the axial force. An upper balance hub is mounted on the upper end of the shaft, and a lower balance hub is mounted on the lower end of the shaft. In order to improve the corrosion resistance and wear resistance, the hydraulic submersible pump adopts advanced material design, such as selecting high quality duplex stainless steel, nickel-cobalt alloy or engineering ceramic materials.

The internal structure of the hydraulic submersible pump indicates a balanced hub; 2-turbo; 3--thrust bearing; 4-axis; 5-leaf-guide wheel; 6-lower-balance hub.

1.2 Working principle In the working process of the hydraulic submersible pump, the ground motor drives the pump to discharge the fluid (oil or water) with a constant pressure. The control valve is used to adjust the pressure and flow of the discharge port of the injection pump, and the fluid is injected into port 1. Wells or wells, power fluid through the wellhead and the central tubing into the upper end of the turbine, through the cross-flow channel into the turbine, driving the turbine rotation, the power of the fluid into the turbine shaft power, the high-speed rotation of the drive shaft, the same The centrifugal pump impeller at the lower end of the root shaft provides the required shaft power.

The tail of the hydraulic submersible pump is threadedly connected to a tail pipe. The outside of the tail pipe is equipped with a packer to seal the annular space inside the tail pipe and the casing. The tail pipe extends into the oil production section to produce oil when the pump shaft rotates at high speed. The liquid in the layer enters into the centrifugal pump from the bottom to the top, passes through the multi-stage vane guide wheel in the centrifugal pump to generate a constant pressure, and finally flows out from the upper-end discharge port of the centrifugal pump.

The above-mentioned structural design of the hydraulic submersible pump allows the flow direction of the produced fluid and the power fluid to be opposite to each other. The axial force generated by the turbine on the shaft and the axial force generated by the impeller on the shaft vane are opposite in direction, and the sizes are close to each other, ie, guaranteed. The device's axial force balance.

The production fluid and the power fluid are mixed in the annular space on the outside of the unit and the inside of the casing. The separation tank that is lifted up and enters into the ground is lifted upwards. In the separation tank, the power fluid and the production fluid are separated, and the produced fluid is separated. The ground pipeline flows into the recycle station, and the separated power fluid flows into the filter. After filtering by the filter, the more compliant power fluid is separated, flows into the water injection pump, and enters the next cycle.

1.3 The main technical parameters / d, head less than 1.4 Technical characteristics 1.4.1 High reliability The new hydraulic submersible pump eliminates underground submersible motors, cables and other electrical components, eliminating all hidden dangers caused by electrical components, and the internal structure Simple and reliable, only mechanical components such as impellers, turbines, shafts and housings are used with very high reliability.

1.4.2 Accommodate inclined and horizontal wells The new hydraulic submersible pump is designed to ensure that the turbine, the centrifugal pump leaf guides and the shaft are fixed in the middle of the unit, and no contact wear will occur between the components due to changes in the tilt angle of the unit. It is suitable for long-term use in inclined wells and horizontal wells.

1.4.3 Has a wide and flexible adjustment range The hydraulic submersible pump is driven by a power fluid. It can regulate the fluid production volume of the downhole centrifugal pump by adjusting the pressure and injection volume of the power fluid, so it has a very wide range of use. The window range of some pumps with wellhead pressure ranging from 3.79 to 6.55 MPa, power fluid flow between 795 and 1590m3/d, and pump production fluid between 1431 and 4293m3/d was given.

Some kind of pump power fluid, wellhead pressure and pump output fluid envelope. 4.4 High gas-liquid handling capacity The hydraulic submersible pump has undergone a revolutionary gas treatment structure design to prevent gas from accumulating at the impeller hub of the pump inlet, thereby avoiding air lock or head loss; in addition, the pump stage uses multiple stages. The design and very wide speed range (speed can reach 3000~10000r/min) can significantly increase the pressure and centrifugal force of the pump wheel and effectively prevent the gas lock from being generated. The gas liquid processing capacity of the hydraulic submersible pump suction port can reach 80 %. 1.4.5 Simple installation Compared with the ESP of the electric submersible pump, there are no submersible motors, motor protectors, and separators. The submersible pumps are at least 25% shorter and do not need flanges and couplings. Threaded connection, so the installation is simple.

2 Prototype test and field application 2.1 Prototype test Before the new type of hydraulic submersible pump was put into field application, it first simulated the oil quality of Captain oil field, collected crude oil, methane and brine from Captain oil field, and performed high oil-gas ratio conditions for the hydraulic submersible pump. Under the production test, the test results confirmed that the new pump can extract viscous oils with different viscosity ranges and well fluids with water content of 0-100%. Another important feature demonstrated in the tests is that it can handle up to 80% GVF slug flow, and it can be adjusted to achieve the required flow rate.

2.2 Field application This new type of pump has been applied in the CaptainA area. The ground uses a 10-stage centrifugal water injection pump and the injection pressure reaches 35 MPa. The hydraulic submersible pump consists of 14 centrifugal pump leaf guide wheels and 20 turbines, initially with 1431m3. In the case of power-driven power supply, the hydraulic submersible pump produced only 477m3 of fluid per day. After that, the power fluid was increased to 1908m3, and the daily displacement of the hydraulic submersible pump was once increased to 1400m3, but then it began to decline until it stabilized at about 715m3. The operating cycle speed of the hydraulic submersible pump is generally within 7000~10000r/min in a few seconds, and the maximum gas-liquid ratio (GVF) of the pump inlet is as high as 80%. This value is 1.5~2 times of the original predicted value, and has been obtained. Good use effect.

In 2009, Clyde United Pumps of the United Kingdom used three new hydraulic submersible pumps in the offshore oil field of Captain B. 4. The new hydraulic submersible pump has 17 pump wheels and 25 turbines. Under the condition of power hydraulic pressure of 510m3/d, The pump speed is 8150r/min, the pumping depth is 762m, and the produced fluid volume is 3180m3/d. The current operation is in good condition.

Districts and B areas have been used in a large number of applications. More than 40 sets have been used, and some hydraulic submersible pumps have reached 6 years in service life, and they are still in normal operation, achieving considerable economic benefits. At present, this type of pump has not yet been used in China. It can be predicted that with the further development of the hydraulic submersible pump technology and the acceleration of the localization process, the pump will have a wide range of domestic large-displacement oil wells, water injection and offshore platforms. Application prospects.

3 Conclusions The new hydraulic submersible pump has the unique features of simple structure and high reliability. The downhole part is completely without electrical components. It eliminates the high temperature and high pressure of the electrical components in the well and requires strict sealing to ensure the strict requirements of the insulation performance. High, long life.

The hydraulic submersible pump has high rotation speed and powerful lifting capacity. The displacement can reach thousands or even thousands of squares per day. This is not achieved by electric submersible centrifugal pumps, so it is irreplaceable in a certain range.

The hydraulic submersible pump is suitable for the installation of inclined shafts, horizontal wells and other arbitrary angles, especially the development of offshore oil fields, and the installation is simple and the operation is convenient. In the use of the pump, the dynamic fluid flow and pressure head size of the surface water injection pump can be adjusted according to the dynamic change of the well conditions to meet the needs of oil well productivity, and has a wide application prospect.