Method of measuring wax precipitation quantity of crude oil

Abstract

The invention provides a method of measuring wax precipitation quantity of crude oil, which includes the following steps: 1) with centrifugal separation technology, enriching wax crystal precipitated from the crude oil in centrifugal filter cake; 2) by means of gas chromatography, obtaining distribution of carbon number in the crude oil and the centrifugal filter cake to determine the mass percentage of solid-state wax in the filter cake; and 3) performing mass conservation data analysis on the basis of four equations to obtain the wax precipitation quantity of the crude oil. In addition, a correction method is disclosed on the basis of the defect of error propagation in an internal standard method of HTGC test of the centrifugal filter cake. By means of the correction method, HTGC test deviation is overcome, thereby improving applicability of the method of measuring the wax precipitation quantity. By means of the mass conservation analysis to the centrifugal separation process, the mass percentage of liquid-phase crude oil wrapped by the centrifugal filter cake can be determined, thereby avoiding the influence of liquid-phase wax components which are dissolved in the liquid-phase crude oil in a result of wax precipitation quantity measurement. The method is increased in accuracy.

Description

technical field [0001] The invention relates to a method for measuring the wax precipitation amount of crude oil. Background technique [0002] Waxes are a class of compounds in petroleum. Broadly speaking, petroleum wax includes liquid wax, petroleum grease, paraffin wax and microcrystalline wax, which is a complex mixed system. The crude oil produced in most oilfields in my country is waxy crude oil. At higher temperatures, the wax in crude oil is in a dissolved state, exhibiting the properties of Newtonian fluids. As the temperature drops, the solubility of light hydrocarbons in crude oil to wax decreases, and wax precipitates due to supersaturation, and the viscosity of crude oil increases accordingly, turning into a non-Newtonian fluid. When the amount of wax crystals precipitated reaches 2%-3%, a three-dimensional network structure can be formed, hindering the flow of crude oil, causing the overall crude oil to lose fluidity and solidify. [0003] In the study of p...

AI Technical Summary

Problems solved by technology

According to the knowledge of liquid-solid phase equilibrium, even if the carbon number is higher than the initial carbon number, this n-alkane will partly exist in solid state and the rest will exist in liquid state. In the method of content, the high molecular weight wax component (the part with carbon number higher than the initial carbon number) that is still in liquid state in the centrifugal filter cake is ignored, and the amount of wax precipitation in crude oil is overestimated

[0010] To sum up, differential scanning calorimetry can only give the wax content in crude oil and the range of wax precipitation curve; there is no accurate linear relationship between the amount of wax precipitation and the absorption peak area in Fourier transform infrared spectroscopy; The repeatability of the experimental data is poor; while gas chromatography overestimates the amount of wax deposited in crude oil, and cannot accurately obtain the amount of wax deposited in crude oil. In order to measure the amount of wax deposited in crude oil more accurately, a new measurement method needs to be developed

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