CZGL-1Vertical pipe flow experimental device

1Function of the device

1. Observe various flow patterns appearing in vertical wellbore and master the method of flow pattern discrimination.
2. Master the calculation method of multiphase pipe flow in vertical wellbore; By conducting experiments, the relationship curve between the liquid production and gas production of the simulated well is measured, and the curve is analyzed to find a reasonable working system.
3. Understand the principle and operation method of the self jetting well simulator;

IIExperimental principle

1. In many cases, when the wellhead pressure of an oil well is higher than the saturation pressure of crude oil, a single-phase liquid flows in the wellbore. When the bottomhole pressure of the self jetting well is lower than the saturation pressure, the entire interior of the tubing is in gas-liquid two-phase flow. The total pressure drop of the oil well production system is mostly used to overcome the gravity and friction losses of the mixture flowing in the tubing. Only when the flow velocity of the gas-liquid phase is high (such as the annular mist flow pattern), kinetic energy loss is considered. In a vertical wellbore, most of the bottomhole pressure is consumed by overcoming the gravity of the liquid column. In the horizontal section of a horizontal well, gravity loss can also be ignored, so the general formula for total pressure drop is: △PTotal=△Ph＋△Pr＋△Pa
2. PhFor gravity descent, △PrTo reduce friction, △PaTo accelerate the descent.
3. During the flow process, the density and friction of the mixture vary along the flow path with the gas-liquid volume ratio, flow velocity, and mixture flow type. The possible flow patterns in oil wells from bottom to top are: pure oil flow, bubbly flow, slug flow, circulating flow, and mist flow. Except for some high-yield condensate gas wells and water containing gas wells, oil wells generally do not experience circulation or mist flow.
4. This experiment uses air and water as experimental media, controls the gas water ratio in the wellbore with valves, and measures the corresponding flow rate and pressure data through instruments. At the same time, the corresponding flow pattern can be observed from the transparent organic tube.

IIIOverall structure

This experimental setup consists of the following parts

1. Simulate vertical well casing

This experimental device has an organic glass tube to simulate actual oil pipes, which can directly observe the flow state of gas-liquid two-phase in a vertical wellbore and simulate the phenomenon of wellbore gas expansion participating in lifting liquid. The relationship between gas volume and liquid production can be quantitatively analyzed.

1. Constant liquid level water tank

Maintain the static water pressure head in the wellbore unchanged.

1. Gas control and metering system

Composed of pressure regulating valve, gas flow meter, needle type fine adjustment valve, etc

This system can input a certain flow rate and pressure of gas into a vertical pipe

1. Quantitative analysis of liquid production volume

Composed of a timer, a liquid measuring tank, etc.

1. Pipeline process system

Composed of pipelines, joints, etc., used to connect vertical pipes, constant position water tanks, liquid measuring water tanks, intake systems, etc.

1. Bracket and control box

4experimental procedure

1. Familiarize oneself with various instruments, control valves, and processes, and check for any air or water leaks in the joints of valves and flow meters.
2. Open the water supply valve to supply water to the constant water level tank and eliminate any air bubbles in the tank and pipeline.
3. Connect the gas source.
4. Open needle valve, intake air. Observe the bubble flow when the gas volume is small, and also observe the slippage phenomenon caused by the gas moving faster than the liquid moving faster. Observe the slug flow when the gas volume is slightly larger, and observe the circulation when the gas volume is larger. After observation, close the needle valve.
5. Measure the relationship curve between liquid production and gas production, close the needle valve, and wait for the wellbore liquid level to stabilize before starting the experiment.

1. Measure the starting point: Slightly open the needle valve to lift the liquid to the wellhead. When the liquid has just arrived at the wellhead and has not yet been sprayed, record the gas flow rate.
2. Measure the points between the starting and stopping points: slightly open the needle valve and stabilize it30SMeasure the cumulative gas flow rate and the amount of water produced in the liquid measuring tank at the same time.
3. The measurement point between the starting and stopping spraying points shall not be lower than10Next time. After each change in flow rate, wait for the flow state to stabilize (approximately30S）Afterwards, the data measurement began.
4. If the water level in the water tank is too high, the drain valve should be opened to release some of the water.
5. Measurement stop point: Adjust the needle valve, and when the gas volume reaches a certain level, only gas and no liquid will be sprayed out from the wellhead. Measure the gas flow rate when stopping the injection. Be careful not to open the needle valve too wide at this time, in order to avoid pumping out the water from the constant level water tank.
6. At the end of the experiment, close the needle valve, water supply valve, and gas source valve, and drain the water in the measuring liquid tank.

5precautions

1. The water supply valve should not be opened too large or too small to prevent water from overflowing from the constant level water tank or causing a decrease in bottomhole pressure when the liquid level is below the overflow.
2. The needle valve can only be opened after opening the gas source valve and adjusting the valve to create a certain pressure inside the flowmeter. Otherwise, water will flow back into the flowmeter, causing inaccurate measurement.
3. When working, only one flow meter can be selected, and all other flow meter valves must be closed.
4. When opening a needle valve, it should not be too large and too small at times. It should be operated slowly from small to large. If necessary, the flow rate can be controlled by a valve instrument on the flowmeter.
5. Do not open the clockwise valve too wide when stopping spraying, in order to avoid pumping out the water from the constant level water tank.