Electrical determination of water content in crude oil using physical properties of capacitance transformer

ELECTRICAL DETERMINATION OF WATER CONTENT IN CRUDE OIL USING PHYSICAL PROPERTIES OF CAPACITANCE TRANSFORMER
Nurullaev Orzikul Ubaevich
Jizpi is a senior teacher of the "Electrical Technology" department.

Abstract: In this article, two methods of determining the water content of crude oil are considered, taking advantage of the physical properties of the capacitive condenser. An electrical circuit consisting of active and reactive elements was used as an indicator to determine the amount of water in oil. Here, the method of determining the capacity based on the change in dielectric permittivity of the medium is considered. This article provides a measurement scheme and calculation formulas.

Key words: oil, crude oil, medium dielectric permittivity, capacitor reactive resistance, triangle of resistances.
Annotation: V dannoy rabote rassmotrena dva sposoba opredeleniya soderjaniya kolichestva vody v sroy nefti s pomoshchyu elektrofizicheskikh svoystv elektricheskih kondensatorov. V kachestve indicatora opredeleniya vlajnosti oil polzovana elektricheskaya scheme sotoyashchikh iz activenykh i reactivenykh elemento. Yomkost kondensara na priamuyu vyazana s elektricheskoy pronetsaemosti issleduemogo obkta. Privedena elektricheskaya scheme izmereniya i raschetnye formulay opredeleniya yomkosti.
Key words: Crude oil, dielectric permeability, capacitor capacitance, reactive resistance, triangular resistance, phase shift, phasometer.
Annotation: In this paper, we consider two methods for determining the amount of water in crude oil using the electrophysical properties of electrical capacitors. An electrical circuit consisting of active and reactive elements was used as an indicator for determining the oil moisture content. The capacitance of the capacitor is directly related to the dielectric constant of the object
under study. The electrical circuit of the measurement and calculation formulas for determining the capacitance are given.
Keywords: crude oil, dielectric permeability, capacitor capacitance, reactance, resistance triangle, phase shift, phase meter.
It is important to determine the quality of oil products at the initial stages of production. One such quality indicator is the water content of crude oil, that is, the water content of crude oil is the main factor affecting its quality indicators. Determining the amount of water in oil is carried out using one of two methods, namely:
- using special sensors (electrodes) placed inside the pipelines during the flow of the extracted or transported product through oil pipelines;
- testing of extracted oil in laboratory conditions of oil samples taken from special reservoirs.
In both cases, we can use the physical properties of the capacitor element as sensors (electrodes) that carry out the measurement (Fig. 1).

Figure 1. Two-electrode capacitance measuring sensor The capacitance of a known flat capacitor:

here:
C=ℇℇ₀^𝑆

𝑑
(1.1)

ℇ - dielectric permittivity of the medium;
ℇ0 - dielectric constant;
S is the surface of the capacitor plate;
d is the distance between the capacitor plates (Fig. 2).

Figure 2. Parallel plate of flat capacitor

To carry out the measurement, we can consider the following circuit in the form of an electrical circuit (Fig. 3).
Figure 3. Electrical scheme of the measuring sensor
is equal to Here: ω=2pf angular frequency. Current passing through this part of the circuit I₃:


I₃=^𝑈а𝑏; (1.3)
Z3


Z₃ – The total resistance in the circuit a) and b) is:

Z₃=√𝑅² + 𝑋²; (1.4)

The X-reactive resistance is X = Xs since this network consists only of Xs.

Based on the expressions given above, the change in the reactance of the capacitor leads to a change in the network current I3. If these quantities are connected together and given in the form of a graduation table, it will be possible to determine the amount of water in crude oil with high accuracy in laboratory conditions using a not so complicated scheme. allows you to determine the angle between:
X X – reactive resistance of the circuit;
R – active resistance of the circuit;
R Z Z – total resistance of the electrical circuit;
φ φ – displacement angle between current and voltage.
The reactance X of the given circuit is directly related to the reactance Xs of the capacitor taken as an indicator, and its change leads to a change in the φ-shift angle.

From the triangle of oppositions tgφ is found.

here:φ = arctg^𝑋 ;
𝑅
We can measure the resulting φ angle with a phasometer, make a table of dependence on the amount of water in the product, and graduate it (Table 1). Table 1

tgφ degree	Xc Oм	W %
30	--	12
20	--	14
15	--	17
10	--	20+

As a conclusion, we can say that if we insert a substance or material whose capacitance should be checked between the plates (shells), then we can see that the dielectric permittivity of the medium between the plates changes to a certain extent, and this, in turn, leads to a change in the value of the capacitor's capacitance.