Hao Fu

Date of Award

5-2021

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Petroleum Engineering

First Advisor

Kegang Ling

Abstract

The pipeline is an efficient way to transport oil and gas over long distances. However, leakage can occur when the pipes have been running for a long time. The leak of energy resources will cause economic loss in millions of dollars, pollute the local environment, and result in safety problems. Therefore, the technology of pipeline leak detection is very crucial during the energy transport process.

The goals of the research are to develop mathematical models based on experimental data and CFD simulation to detect single and multiple leaks in a pipeline and/or pipeline system. The new methods use daily recorded pipeline transportation data such as pressure, temperature, and flow rate to locate leak points and estimate the severity of the leak. The distinct features of this method are the ability to: 1) differentiate single leak and multiple leaks, which is not available in other models, 2) locate the single leak or multiple leaks in a pipeline, 3) locate the leak in parallel pipelines. In addition to petroleum pipelines, the leak detection methods will have broad applications in other pipeline systems. Overall, the location of single and multiple leaks in different pipeline systems can be detected by mathematical models.

The procedure of the studying is listed as following. 1) To build CFD simulation models to simulate the fluid flow in the leaking pipeline system. 2) Modifying the pipeline flow loop for an experiment to simulate leakages in a pipeline and paralleled pipelines. Then, to conduct the detection of a single leak and multiple leaks by laboratory investigations. 3) Recording flow parameters by LabView during the experiment. Then, to use recorded transportation data such as pressure, temperature, and flow rate to locate and estimate the severity of the leakage and compare them with CFD simulation results for different leak scenarios. 4) Using Origin or Matlab to build mathematical models based on the dimensionless variable analysis. After that, to detect leakages through mathematical models, which will be verified by numerical modeling and experimental results.

When the pressure drops between the inlet and outlet of the pipeline, the inflow rate, and the outlet flow rate are measured, the leak location can be detected by the prediction model. Some results are yield according to the research. 1) By measuring the pressure drop of pipe, it can be obtained that at the same leak point, when the dimensionless leakage rate is larger, the dimensionless pressure drop between the inlet and outlet of the pipe is lower. If the same leak rate is maintained, the closer the leak point is to the inlet, the lower the pressure drop through the pipe. 2) The pressure drop in the pipeline of CFD simulation is consistent with the data obtained in the experiment, which indicates the reliability of the CFD models. 3) Multiple inflow rates are necessary for detecting multi-leaks in a pipe or paralleled pipeline system. At different inflow rates, no matter how the pressure drop varies, the leak locations are still the same. 4) Using the method of dimensionless variable analysis, the mathematical model is constructed by a series of parameters such as dimensionless leakage rate, dimensionless leakage location, and dimensionless pressure drop. The mathematical model can be used to determine the location of the leak point in a real-world accident.

The research is of great significance in using flow parameters to detect the leakage. To the best knowledge of the author, the dimensionless variable analysis was barely applied to the detection of leakages in a pipeline or paralleled pipeline system. The results of the CFD simulation and experiments verified the validity and accuracy of the mathematical model which is based on the dimensionless parameter analysis.

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