Measuring the Oil Weight of Crude Oil Storage Tanks Based on the Density Method

Abstract

The measurement of crude oil production of crude oil storage tanks has been a hot issue in the petrochemical industry, while crude oil storage tanks usually contain oil, water, oil and water mixture, as well as sediment and other media. Domestic measurement methods generally have poor stability, low accuracy and most of them can not realize the level measurement of multiphase media within the tank, this paper presents that the weight of crude oil can be measured based on the density method, the density value of oil and water mixture can be obtained by differential pressure transmitter and ultrasonic level sensor, thereby the crude oil production accurately in the tank could be calculated precisely. Introduction Since water injection method is widely used in oil exploration in the petrochemical industry, so the crude oil explored contains much moisture and impurities and need to stand in a crude oil storage tank, under the action of gravity, there are natural gas layer, oil layer, aqueous layer and impurity layer. Thus, how to measure the liquid level of each of medium the dielectric layer to accurately calculate crude oil production is a research hotspot at home. Currently, the most commonly used domestic measurement methods include scale artificial methods, mechanical float method and radar method, some of these measurements can not achieve the measurement of level height of the multiphase medium within the tank, while some are costly or less efficient, so this paper studies how to measure accurately the weight of crude oil in the tank by density method. Measuring Principle: In the crude oil storage tank, if the total volume of oil-water is V, the volume of crude oil with water in storage tanks is w V , the volume of pure oil in storage tanks is o V . Suppose in the case of oil and water incompatibility, then w o V V V   (1) According to the law of conservation of mass, then w w o o m V V V      (2) Where: m  stands for the mixed density of the aqueous crude; o  stands for the density of pure oil; w  stands for water density. Deform formula (1) into w o V V V   and take it into formula (2), then comes International Conference on Applied Science and Engineering Innovation (ASEI 2015) © 2015. The authors Published by Atlantis Press 2175 o w o m w V V          (3) Where:  stands for Volumetric water content in crude oil storage tanks. From equation (3), the weight of pure oil in crude oil storage tanks can be inferred o o V M   ) 1 (   (4) Where: o M stands for the weight of crude oil in storage tanks. Crude oil storage tanks in this article are all standard, namely cylindrical tanks. If the cross-sectional area for crude oil storage tank is S, tank liquid level is H, then o o HS M  ) 1 (   (5) The water content per kilogram in the tank is