Pick To: The oil and gas transport pipeline leakage caused huge economic losses and environmental pollution. Therefore, it is especially important to study and select suitable leak detection methods for oil and gas pipelines. Some methods of leak detection and location of oil and gas pipelines at home and abroad are summarized, as well as the basic principles, advantages and disadvantages of these methods, and the existing problems and development directions are explained.
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Oil and gas transmission pipelines occupy an important position in the national economy and military tasks, and pipeline leakage is seriously jeopardized, causing huge economic losses and environmental pollution. The paper summarizes the methods, advantages and disadvantages of some methods and several methods for oil and gas pipeline leakage detection and location at home and abroad, and explains the existing problems and development directions.
1. Pipeline leak detection method based on evaluation model
1.1 Transient flow model method
During the change in pipeline capacity (flow changes), transients are induced in the tubes, creating transient pressures and pressure waves. The method is to perform real-time numerical simulation on the state change of the pipeline transportation medium, and the mathematical model parameters are established: instantaneous flow rate, instantaneous pressure, instantaneous temperature and the like. It is carried out by computer technology, and the leakage is detected based on the deviation between the calculated value and the measured value. This method is suitable for the judgment of large leaks and is not sensitive enough for small leak detection. It has been applied in SCADA systems.
1.2 Pressure Gradient Method Based on Pipeline Thermal Comprehensive Model
Principle of pressure gradient method: When the pipeline is normally transported, the pressure gradient of the pipeline between the stations is oblique. When a leak occurs, the pressure gradient before and after the leak is in a zigzag shape, and the breakpoint is the leak point. Leak location. In practice, the pressure gradient along the line is nonlinear, and the positioning accuracy of the traditional pressure gradient method is poor. In response to this problem, domestic scholars have established a comprehensive hydraulic and thermal model that reflects the thermal changes along the pipeline, and finds a nonlinear pressure gradient distribution law that better reflects the actual situation and conducts leak location. This method shows great advantages for pipelines in which crude oil (or other fluids) has a large change in viscosity, density, specific heat capacity, etc., with a large change in the temperature along the path. However, this method requires a flow signal and needs to be complicated. The mathematical model is computationally intensive.
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