A Method for Measuring the Viscosity of Heavy Oil

Abstract

The invention discloses a method for measuring the viscosity of thick oil. The method comprises the following steps: heating a high pressure falling ball viscometer to a formation temperature, maintaining the formation temperature for more than 4 hours, evacuating the viscometer; fully filling a pressurized pipeline, the high pressure falling ball viscometer, and a sample transfer pipeline with a saturated zinc sulfate solution; lifting the pressure of the high pressure falling ball viscometer to the formation pressure value; communicating a sample storage device with the sample transfer pipeline; maintaining the formation pressure, continuously reducing the volume of a high pressure metering pump (A) to pump a crude oil sample into the high pressure falling ball viscometer to replace and discharge the saturated zinc sulfate solution in the high pressure falling ball viscometer, after all zinc sulfate solution is discharged, keeping on pumping 20 mL of crude oil sample into the high pressure falling ball viscometer; and measuring the ball falling time according to a measuring rule. According to the method, a mode of displacement of fluids with different properties is adopted to realize the stratum thick oil fluid balanced sample transfer so as to ensure that during the thick oil sample transfer process, the state and properties of the fluid are not changed, thus the uniqueness and stability of fluid tests can be guaranteed, and the analysis results are real and reliable.

Description

technical field [0001] The invention relates to a method for measuring the viscosity of heavy oil, in particular to a method for measuring the viscosity of heavy oil and super heavy oil by using a falling ball viscometer. Background technique [0002] Heavy oil is crude oil with high asphaltene and colloid content and high viscosity. Usually, crude oil with a surface density greater than 0.943 and an underground viscosity greater than 50 centipoise is called heavy oil. In the prior art, a falling ball viscometer is often used to measure the viscosity of crude oil. The method is: first evacuate the viscometer, transfer the single-phase crude oil into the viscometer and maintain the pressure to flush more than 2 times the volume of the viscometer, so that the fresh single-phase crude oil sample Fill the viscometer. For ordinary falling ball viscometers, the total volume of the sample transfer line and the viscometer is 20-35ml. For heavy oil fluids, due to the high viscosity ...

AI Technical Summary

Problems solved by technology

For ordinary falling ball viscometers, the total volume of the sample transfer line and the viscometer is 20-35ml. For heavy oil fluids, due to the high viscosity and slow flow speed of heavy oil, it is difficult to ensure that the oil sample entering the viscometer is always in the Single-phase state, resulting in changes in the state and properties of the test fluid, unstable analysis results, and large errors

Moreover, due to the high viscosity of the heavy oil sample, the small diameter of the sample transfer pipeline, and the excessive length of the pipeline, pipeline blockages occur from time to time during the viscosity test sample transfer process, and even the stability of the entire pressure system is affected by the pipeline blockage, resulting in pressure The phenomenon of uneven distribution and sample degassing leads to low accuracy of viscosity test data

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