In the previous article, we talked about what is the difference between API sucker rod pump and submersible electric pump?
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This article continues to show you what is the difference between API tubing pump and electric submersible screw pump?
Overview of API tubing pump:
1. Composition of API tubing pump:
The pump barrel assembly of API tubing pump is directly connected to the lower end of the oil pipe, and the plunger goes into the pump barrel with the sucker rod. API tubing pump consists of two parts: pump barrel assembly and plunger assembly. The pump consists of a pump barrel, a fixed valve and a hollow plunger with a floating valve.
2. Working principle of API tubing pump:
During the pumping process, the plunger reciprocates up and down in the pump barrel with the movement of the sucker rod. During the upstroke, the floating valve ball on the plunger is closed, the fixed valve ball is opened, and the plunger discharges the liquid in the upper chamber into the upper oil pipe of the pump. At the same time, the liquid in the well enters the lower chamber of the pump barrel through the fixed valve under the action of the inlet pressure. During the downstroke, the fixed valve is closed, the floating valve is opened, and the liquid in the lower chamber of the pump enters the upper chamber of the pump barrel through the inner cavity of the plunger. The plunger surges up and down, and the liquid is continuously pumped to the wellhead.
3. Analysis of the reasons for API tubing pump repair:
For coalbed methane wells, repair is mainly caused by eccentric wear and pump failure. Well repair requires all the pipes to be lifted out of the ground. There is a detailed description later.
4. Scope of use:
API tubing pump has the characteristics of strong adaptability to well types, a wide range of of API tubing pump diameter selection, relatively easy daily operation and maintenance, and low initial investment and operating costs. API tubing pump is generally suitable for the production of coalbed methane wells, but of API tubing pump also has serious problems of eccentric wear of pipes and rods, poor adaptability to coal powder and poor adaptability to horizontal wells.
Overview of electric submersible screw pump:
1. Composition of electric submersible screw pump:
The complete set of electric submersible screw pump equipment consists of two parts: ground control system and downhole screw pump system. The ground control system mainly includes control cabinet, power supply (generator set or power grid) and various cables; the downhole screw pump system mainly includes motor, pump, check valve, downhole pressure sensor, oil pipe and various cables.
The transmission structure of the electric submersible screw pump is simple and the overall size is small. It can pass through any well section with a dogleg angle below 16.5°/30m, and is especially suitable for application in inclined wells and horizontal wells.
The electric submersible screw pump system has two series, A and B, with a total of 6 pump types, which can provide a head of less than 1000m, a displacement of 1.5m3/d to 50 m3/d and a well condition with a temperature below 80℃.
2. Principle of electric submersible screw pump:
The core idea of the automatic control system of the electric submersible screw pump is to stabilize the liquid level and intelligently control it, which is divided into manual and automatic modes. Manual mode (Manual) operates according to the set fixed speed instead of the liquid level; automatic mode (Automatic) is that the system operates according to the dynamic liquid level. In automatic mode, when the liquid level is above the target level, the electric submersible screw pump will run at a higher speed. After the liquid level drops to the target level, the system automatically reduces the speed to stabilize the liquid level at the target level. If the screw pump still cannot keep the liquid level stable at the target level at the lowest speed, the system will let the unit run at the lowest speed until the liquid level drops to the shutdown level, and the unit will automatically shut down. When the liquid level rises to the recovery level, the unit will automatically start.
3. Analysis of the reasons for the repair of electric submersible screw pumps:
The formation liquid enters the annular space between the pump body and the guide cover through the screen on the upper part of the guide cover, reaches the suction port, and the screw pump works to produce the liquid to the ground. The bottom of the guide cover is sealed by a sealing ring. It is easy to accumulate coal powder or corrode and harden the sealing rubber in the space from the suction port to the sealing ring. For wells with large coal powder output, it will accelerate the wear of the pump or cause the pump to get stuck, shortening the pump inspection cycle; for highly corrosive drainage and production water, the motor will also be flooded due to corrosion and hardening of the sealing rubber. And the ground operating cabinet has high requirements for the stability of the current.
4. Scope of test use:
Compared with the rod pump, the electric submersible screw pump has the following advantages: it can adapt to the maximum well inclination of 70°; the gas-liquid ratio has a wide range of applications and does not cause gas lock; the suction is continuous and stable, and does not disturb the coal seam; there is no sucker rod, which eliminates the loss caused by rod and pipe wear or tripping; smaller-sized oil pipes can be used to enhance the ability to carry coal powder; the ground occupies a small space, is noiseless, and has simple daily management; the pumping depth and displacement can be increased. However, there is also a high liquid production (the daily water production cannot be less than 2m3), and a drainage and production water injection device needs to be installed to meet the needs of the drainage and production system.
Since the maximum outer diameter of the electric submersible screw pump is 114mm, considering the outer diameter of the oil pipe joint hoop, the 20mm2 large flat cable and the cable clip, the maximum outer diameter of the pipe string is quite close to the inner diameter of the casing. If the wellbore spits sand and coal powder, the formation fluid is easy to scale, and the risk of getting stuck during the oil pipe lifting process is high. Moreover, the submersible screw pump requires a submergence greater than 200m, which makes it difficult to meet the drainage requirements in the later stage of drainage.
Maintenance and operating costs:
Once the API tubing pump fails, all the oil pipes and sucker rods need to be pulled out, which requires a large amount of maintenance work and a long period of time. But in general, the probability of our Dongsheng pump being repaired in actual customer cases is relatively low. So you can use API tubing pump with confidence (click to jump to the relevant detailed product content)
Operating cost: The initial investment of API tubing pump is low, which is suitable for shallow wells, stable production, and mild well conditions.
When the submersible screw pump fails, the entire pump system and cable need to be pulled out, which has high technical requirements; generally, coal powder stuck in the pump, seal failure, and cable aging are common problems of submersible screw pumps. If the guide cover is seriously sanded or powdered, it may cause the pump body to get stuck or the motor to get water.
Operating cost: high initial investment (pump + control system).
What scenarios are they applicable to?
API tubing pump applicable scenarios
1.API tubing pump is suitable for medium-shallow well depth (<1000m).
2. Low well inclination.
3. Medium-low daily liquid production.
4. Simple wellbore structure, less scaling and coal powder content.
5. API tubing pump is suitable for early trial production or production stabilization period requiring low-cost investment.
Applicable scenarios for electric submersible screw pumps:
A. Inclined wells, horizontal wells or wells with inclinations up to 70°.
B. Complex downhole structure, high sand and powder content, and more gas-liquid mixed fluids.
C. Gas wells or coalbed methane wells that require high automation management.
D. Well sites with limited ground space and high requirements for noise and operation interference.
E. More suitable for medium-deep wells, high-lift occasions, and production layers with high daily liquid discharge requirements.
Which equipment should be selected for different well conditions?
① For early low-yield and cost-sensitive coalbed methane wells, API tubing pumps can be used for initial drainage, which has cost advantages.
②If you are currently facing a situation where the well is deep, the coal powder content is high, or the well is inclined/horizontal, it is recommended to use an electric submersible screw pump. In comparison, the electric submersible screw pump has wide adaptability, high degree of automation, and stronger stability.
③There are a variety of well types mixed in the well site. The efficiency will be better if they are graded and selected according to the well depth, liquid production, sand content, etc.
④For wells where the liquid production decreases in the later stage of drainage but still needs to maintain stable operation, it is possible to consider changing from an electric submersible screw pump to a more economical API tubing pump system to reduce operating costs.
What is the difference between a rod pump and a submersible electric pump? What is the difference between an API tubing pump and an electric submersible screw pump? We will stop here for these two articles! If you want to know more related information, follow our website so that you can read more related information!