Oilfield wastewater, the water that is extracted from oil wells along with crude oil. Usually contains oil, salt, mechanical impurities, dissolved oxygen and saprophytic bacteria. Pollution to the oil field and the surrounding environment. After treatment, it can be reinjected back into the oil layer to be used as an oil displacement agent. Most of the time, electromagnetic flowmeters are used to measure oilfield wastewater.
Difficulties in Oilfield Wastewater Measurement
With the growth of oil demand and the improvement of oil extraction technology, the amount of oil extraction wastewater treatment is increasing day by day. Effective control of oil production wastewater pollution and the utilization of wastewater resources have become key issues facing oilfield development.
The first thing to do in wastewater treatment is to accurately measure the oil production wastewater. Only by accurately measuring the amount of wastewater can scientific and reasonable wastewater treatment and wastewater scheduling be carried out. After the wastewater is treated up to the standard, most of it will be used as mining injection water and re-injected into the formation.
Turbine flowmeters used in some early Oilfield Wastewater. The error between the instrument measurement data and the measurement tank data reaches more than 20%, which causes a great waste of on-site resources.
- Oil production wastewater carries a large amount of suspended solids. The inner blades of the turbine flowmeter are easy to be jammed and damaged, and need to be dismantled and maintained regularly;
- Turbine flowmeters used in different pipelines and process links are not universal. On-site instrument maintenance is difficult;
- The flow rate of the 2-inch pipe is less than 70 cubic meters per day. The micro-flow turbine flowmeter cannot measure accurately;
- The lower end of the coupling device is easy to accumulate impurities, which makes the measurement accuracy low. The tiny traffic of some sites cannot even be measured;
- Oil production wastewater has a high temperature and contains different salts and other impurities. It is easy to corrode the turbine flowmeter.
Oilfield wastewater classification
Before sewage treatment, it is particularly important to determine its composition. The sewage on the oil field is divided into general sewage and drilling sewage:
- General waste water
The main components are water, secondary clay minerals, mercaptan (RSH), sulfide (RSR), disulfide (RSSR) and other components condensed together by various substances.
For the composition of general sewage, because it contains more impurity particles, and the water is more acidic or alkaline. Therefore, the selected electromagnetic flowmeter can be measured with rubber or PTFE lining, and used with stainless steel electrodes.
- Drilling sewage
The main components are drilling fluid, flushing fluid, etc. Its main pollutants include drilling cuttings, petroleum, viscosity control agents (such as clay), weighting agents, clay stabilizers, corrosion agents, preservatives, fungicides, lubricants, formation affinity agents, defoamers, etc. Drilling sewage also contains heavy metals and so on.
Drilling sewage contains more chemical synthetic agents, complex components, strong acidity and alkalinity and corrosiveness. It also contains some heavy metal ions. In order to ensure good detection and stability of the flowmeter, it is usually necessary to choose a polyurethane or polyperfluorinated lining for measurement. At the same time, tantalum electrodes or Ha C electrodes are used.
Application of Electromagnetic Flowmeter in Oilfield Wastewater and Oilfield
The advantages and working principles of electromagnetic flowmeters have been mentioned in many pages. I won’t repeat it here.
Electromagnetic flowmeters play an important role in water irrigation, polymer injection and sewage metering in oil fields.
The use of electromagnetic flowmeters in the measurement of oilfield wastewater has the following advantages.
①The structure of the sensor is simple and reliable. The diameter is the same as that of the front and rear straight pipe sections. And there are no moving parts in the flow channel. There are no parts to block the flow of the measured liquid and save equipment. There will be no jamming or jamming;
② The measured medium flows through the measuring tube. There is almost no loss of pressure, which can significantly reduce the consumption of the driving force of the pump;
③ The output current and frequency of the electromagnetic flowmeter have a linear relationship with the measured flow. It is not affected by the measured medium (temperature, pressure, viscosity). Therefore, the electromagnetic flowmeter can be used to measure crude oil with sandy content or high water content only after being calibrated with water without modification;
④ Electromagnetic flowmeter has no mechanical inertia and quick response. Instantaneous pulsating flow can be measured. It is convenient for the monitoring of the production site.
Selection of Electromagnetic Flowmeter for Measuring Oilfield Wastewater
It is very important to choose the type of instrument including the magnetic flowmeter. Some failures of instruments in practical applications are caused by wrong selection or improper use. Therefore, after selecting an electromagnetic flowmeter, the following factors should be considered:
- Aperture Selection
According to the process pipe diameter, pipe pressure and sewage flow provided by the sewage treatment plant. Choose an electromagnetic flowmeter with an appropriate diameter, and there is no need for pipe shrinkage and expansion at the installation site.
- Selection of Liner and Electrode Materials
Electromagnetic flowmeters are mainly used to measure fluid flow with a conductivity greater than or equal to 5 pressure S/cm. Different lining and electrode materials should be selected according to the corrosiveness, wear, temperature and condensation characteristics of the tested material and its bearing capacity.
- Select the protection level
According to national standards, the sensor has two levels of protection: IP65 water jet type and IP68 submersible type. According to the actual installation position of the user in the low well, the sensor adopts IP68 dustproof submersible type.
- Select other functions
(1) For the selected basic type, the electromagnetic flowmeter has LCD display, 4-20ma current output and 0-1khz frequency output. The function of the Rs-485 communication port should be added according to the communication requirements of the flowmeter and the computer.
(2) For sensors installed underground, split type should be selected.
Featured Magnetic Flow Meters
More solutions for wastewater flow measurement
The flow of Oilfield Wastewater varies greatly, contains impurities, and is less corrosive, regardless of general sewage or drilling sewage. It contains many ions and has high conductivity. Combined with the unique characteristics of not being disturbed by external factors such as temperature, pressure and viscosity. Electromagnetic flowmeter is undoubtedly the most suitable choice for oil field sewage flow measurement.
In addition, in the sewage treatment process, large-diameter flowmeters are mostly split. One part is installed underground and the other part is installed on the ground. The small caliber is mainly integrated. In the water supply and drainage and sewage treatment industries, electromagnetic flowmeters, especially large-caliber electromagnetic flowmeters, have great advantages.
If you encounter a situation where the electromagnetic flowmeter is not applicable for Oilfield Wastewater. I think the target flow meter is a good choice. It is accurate in measurement, and the measurement structure is not affected by the physical characteristics of the medium temperature, pressure, conductivity, and the amount of impurities that are easily contained. The operation is stable and reliable, and it is resistant to high temperature, shock and wear. Long service life, easy to install and use.
If you need to Measura Oilfield Wastewater with Electromagnetic Flowmeter, or have any technical questions about Oilfield Wastewater, please feel free to contact our engineers.
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