A hydrate blockage detection apparatus for gas pipeline using ultrasonic focused transducer and its application on a flow loop

Abstract

This paper introduces a novel apparatus and the analyzing method for hydrate blockage detection in natural gas pipeline using the ultrasonic focused testing technique. The apparatus mainly consists of three parts: an ultrasonic focused transducer, a supporting guide track and a positioning ruler for the transducer. It can be installed by fixing the guide track onto the pipe outer wall, and the distance of the transducer to the pipe wall can be adjusted with the positioning ruler. The reflection signals of hydrate surfaces can be then received and recorded by an oscilloscope. The hydrate thickness thus can be calculated by multiplying the ultrasonic velocity with the time difference between two reflections. A calibrating test using this apparatus certified that it can provide an accurate measurement of both the pipe wall thickness and the hydrate blockage thickness from outside of the pipe. A maximum hydrate thickness of 50 mm can be measured due to the high penetrability of the ultrasonic. The feasibility of applying this apparatus to the metal pipeline was verified with a carbon steel cylinder with ice attached on the inner wall. A 360° blockage profile around the cylinder was obtained with a step angle of 5°. The accuracy of measured thickness and cross‐sectional area of the blockage can reach 96% and 91%, respectively. Finally, an application test was conducted on a full visible flow loop of 35 mm inner diameter and 49 m length. The test results showed that the hydrate blockage contour measurement can be achieved with this apparatus despite the gas and water flow in the loop. This hydrate blockage detection apparatus can be applied to gas‐dominated pipelines in which hydrate mainly forms on the wall. Early warning of hydrate blockage can be further studied based on the measurement results using this apparatus.

Status of Natural Gas Hydrate Flow Assurance Research in China: A Review

“…An and co-workers , analyzed the chaotic characteristics of the detection signal to distinguish hydrate blockage and leakage, realizing the online detection and location of hydrate blockage. Li et al introduced a new device that uses ultrasonic focused testing technology to detect hydrate blockage in natural gas pipelines and calculate the thickness of hydrate deposition on the pipe wall.…”

Hydrate Dissociation Using Microwaves, Radio Frequency, Ultrasonic Radiation, and Plasma Techniques

“…On the other hand, pore space characteriza-tion using ultrasonic waves was performed by Schindler et al [41]. Recently, a more novel method of detecting natural gas hydrates using ultrasonic assisted technique was developed by Li et al [42]. Evidently, ultrasonic waves find a much more diverse span of application ranging from detection and characterization to hydrate dissociation.…”

“…3. As discussed earlier, the use of electromagnetic radiation for enhanced oil recovery is well known [35,41,42]. However, application of electromagnetic radiation for gas recovery from natural gas hydrate reservoirs is still largely unexplored territory.…”

Influences of Hydrogen Blending on the Joule–Thomson Coefficient of Natural Gas

“…The cooling produced in J–T expansion has been a double-edged sword in natural gas engineering. For example, the temperature drop caused by the J–T effect during natural gas transportation can cause gas hydrate blockage at the pipeline valves; , in the production of natural gas hydrate, the temperature change induced by the J–T effect has significant impacts on the production efficiency; in natural gas liquefaction, the cooling produced in the J–T expansion can be used to liquefy natural gas, etc. Therefore, it is of great engineering significance to study the J–T effect of natural gas.…”