Detection method and system for simulating wax deposition in crude oil pipeline conveying process

Abstract

The invention provides a detection method and system for simulating wax deposition in a crude oil pipeline conveying process. The method comprises the steps that a high level storage tank, an oil sample container and a low level storage tank are installed in a sequentially lowered mode; a first water bath, a temperature control interlayer of the high level storage tank and a temperature control interlayer of the oil sample container form a first closed loop; a second water bath and a hollow interlayer of a cold finger form a second closed loop; a stirrer is arranged in a hollow part of the cold finger, the stirring rate of the stirrer is changed, and the stirring rate corresponding to the shear rate under the simulated pipeline conveying condition is obtained; stirring is maintained, sediment is stripped away from the surface of the cold finger after an experiment is over, and weighing and calculating are conducted to obtain the increase rate of a wax deposition layer. The system at least comprises the high level storage tank, the oil sample container, the low level storage tank, the cold finger, the temperature control water baths and a connecting pipe. By constructing an oil sample passageway and establishing a wax deposition temperature field, continuous update of oil samples in the sample container is realized, pipe flow shear is simulated quantitatively in a stirring mode, and the wax deposition detection process is more approximate to the actual pipeline conveying condition.

Description

technical field [0001] The invention relates to a method and system for detecting wax deposition in the simulated crude oil pipeline transportation process, belonging to the field of crude oil gathering and transportation. Background technique [0002] Wax in crude oil refers to a mixture of n-alkanes with a carbon number greater than 17, mainly manifested as paraffin wax and microcrystalline wax. 80% of the crude oil produced in my country is waxy crude oil, among which the waxy content of the typical Daqing Oilfield crude oil is as high as 26.3%. The solubility of wax components in crude oil is limited. When the temperature is lower than the wax precipitation point, high-carbon wax molecules are first precipitated as solids. As the temperature decreases, the amount of wax precipitation increases, and the initial carbon number of the precipitated wax crystals gradually decreases. For crude oil pipelines laid in cold regions, the temperature of the pipe wall is lower than t...

AI Technical Summary

Problems solved by technology

Based on the shear stress (the product of crude oil viscosity and shear rate) on the wall of the sediment layer during the actual wax deposition process is closely related to the flow velocity and flow state, and the small loop in the loop method cannot simulate the actual pipeline flow by adjusting the flow rate The shear stress on the wall of the middle sediment layer, that is, the flow rate and the shear rate cannot be simulated at the same time

In addition, the loop test device is complex and needs to be equipped with flow and pressure test devices and automatic control equipment, resulting in a large area and high investment costs. Only a few famous universities and oil company scientific research institutions have built loop devices

[0006] In summary, the existing crude oil wax deposition detection methods have certain defects in simulating the wax deposition process of actual oil pipelines. In order to make the wax deposition detection process closer to the actual situation of pipeline transportation, new methods need to be studied

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