RU2386959C1 - Definition method of water content and summary content of metal-containing microelements in oil or oil-products - Google Patents

Abstract

FIELD: oil-and-gas production.

SUBSTANCE: definition method of water content in oil and oil-products in flow of pipeline includes measurement of complex electric conductance of oil and oil-products at two frequencies: at frequency f₁ and at working frequency f₂ (f₁<f₂) then it is implemented temperature correction of measurable parametres, it is defined ratio of η complex quantities of electric conductances at two different frequencies, it is defined mass fraction metal-containing microparticles δ and by value of ratio η it is implemented identification process, and by value of ratio

it is implemented elaboration of type of oil and oil-product, and sum content of water in oil or in oil-product is calculated by gauge model, corresponding to particular type of oil or oil-product.

EFFECT: increasing of determination accuracy of water in oil and oil-products and ability of receiving of stationary gauge model by types of oil by deposit or mix oils.

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Description

The present invention relates to the study of the physicochemical properties of oil and oil products and can be used to identify the type of oil in the field or mixed, as well as determine the water content and the total content of metal-containing trace elements in oil and oil products directly in the pipeline stream.

A known method for determining the percentage of water in petroleum products using the dielectric method [Tareev BM Physics of dielectrics. M .: Energoatomizdat], in principle of which lies the measurement of the dielectric constant of dehydrated and crude oil. According to the Lichtenecker-Rother formula, the dielectric constant of a mixture consisting of two components - water and oil, depends on their volume ratio

where y ₁ and y ₂ are the volume fractions of water and oil;

ξ ₁ is the dielectric constant of water;

ξ ₂ is the dielectric constant of dehydrated oil;

ξ ₃ - dielectric constant (mixture) of crude oil.

Given the known value of the dielectric constant of water ξ ₁ - expression (1) is converted to

Thus, to determine the percentage of water, it is sufficient to measure the dielectric constant of the mixture ξ ₃ and the dehydrated product ξ ₂ .

The disadvantage of this method is the inability to determine water in oil and oil product in the pipeline flow, the method requires sampling of the studied product, and most importantly there is no identification of the type of oil by field or mixed oil, which gives a large measurement error in the study of unknown oil and there is no measurement of the total metal content trace elements. In addition, relation (1) is valid for a low water content in oil.

The basis of the invention is to create a method for determining the water content in oil and oil products, identifying oil and oil products and determining the total content of metal-containing trace elements, which would improve the accuracy of determination of water in oil and oil products and would allow a stationary calibration model for the types of oil in the field or mixed oils.

The problem is achieved in that in the method for determining the water content in oil and oil products, which consists in determining the dielectric constant ξ _{f1 of} crude and dehydrated oil at the first frequency of the sinusoidal voltage generator f ₁ , the dielectric constant ξ _{f2 is} additionally measured at the second frequency f ₂ , in fact we measure the complex conductivity of the investigated product G _f1 and G _f2 , which is proportional to the dielectric constant of the product, the ratio is determined

during calibration, these ratios are oil classifiers, i.e. they identify the type of oil or oil product, since the water content depends on the dielectric constant of the oil, it is necessary to take into account the significant contribution of disturbing effects on the dielectric constant, such as gas inclusions and the presence of metal-containing trace elements, for this the total content of metal-containing trace elements δ is additionally determined, so Thus, the measurement error from gas inclusions is excluded when identifying oil by the field and, accordingly, Calculating the water content of crude oil or petroleum product, then at a frequency f ₁ determines the total increment of permittivity relative to known dielectric constant to dehydrated oil, count increment dielectric constant per unit concentration of water, and further with respect these increments at a frequency f ₁ determines the total increment dielectric constant relative to the known dielectric constant for dehydrated oil, we calculate the dielectric increment permeability per unit concentration of water, and then with respect to these increments at a frequency f ₁ determine the mass fraction of water in oil by the formula

where U _ξ0 is the proportional value in [B] relative

dielectric constant of dehydrated oil at t = 20 ° C;

U _ξ20 is the proportional value in [V] relative

dielectric constant of crude oil reduced to 20 ° C;

Δ is the increment of the relative value of the dielectric constant of oil per unit concentration of water.

Figure 1 shows a functional diagram of a device for implementing the proposed method.

Figure 2 shows the dependence of the complex electrical conductivity of oil of various types on frequency.

The device contains a segment of a polymer pipe 1, a primary transducer 2, made in the form of copper plates 3, mounted on the surface of the pipe, a magnetometer 3, mounted around the circumference of the pipe 1 in the form of a bracelet, a temperature sensor 4, a two-channel switch 5, a generator 6, a working generator frequency 7, the first measuring amplifier 8, the second measuring amplifier 9, computer 10, the outputs of the generators 6 and 7 are connected to the inputs of the switch 5, the output of which is connected to the first plate of the Converter (capacitor) 2, W the paradise plate is connected to the input of the first measuring amplifier 8, the output of which is connected to the first information input of the calculating device 10, the output of the sensor magnetometer 3 is connected to the input of the second measuring amplifier 9, the output of which is connected to the second information input of the calculating device 10, output the temperature sensor 4 is connected to the third information input of the computer 10, the control outputs of the computer 10 are connected to the corresponding control inputs of the switch 5.

The method is as follows.

Oil, which is a dielectric and acts on the capacitance of the capacitor (plate 2) of the primary converter, which is made in the form of a capacitor, through which the sinusoidal voltage passes, alternately includes the frequencies f ₁ and f ₂ through the segment of the polymer pipe 1, which is cut into the oil pipeline, , f ₁ <f ₂ . The dependence of the complex conductivity on the frequency of the signals and temperature for different oils and mixed products is different (figure 2).

For each product, the level of conductivities and their increments Δ ₁ , Δ ₂ , ..., Δ _i per unit of frequency differs significantly, there is also a difference in the increments of the dielectric constant per unit frequency.

The ratio is determined

which is the identification of oil by field or a mixture of various oils.

To do this, through the switch 5 alternately connect the sinusoidal signal generators 6 and 7 with a frequency of f ₁ and f ₂ , f ₁ <f ₂ , to the input of the sensor 2, the signal from the sensor 2 through the measuring amplifier 8 enters the calculating-solving device 10, where and the ratio is calculated

Based on the calculation result, a specific calibration model for a given oil is selected, and the mass fraction of water in oil is calculated by the formula (2) based on the measurement results of the dielectric constant of the oil at the operating frequency f ₁ .

Since the principle of operation is the dependence of the dielectric constant of oil on the water content, it is necessary to take into account the significant contribution of disturbing effects on the dielectric constant, such as gas inclusions and the presence of metal-containing trace elements in oil, to increase the accuracy of determining the water content. For this, a supersensitive sensor magnetometer 3 is used, which picks up magnetic disturbances generated by metal-containing microparticles, the sensor signal is amplified by an amplifier 9 and read by a counting-resolving device 10. Thus, we obtain a value characterizing the mass fraction of metal-containing particles δ, affecting the dielectric constant of oil and petroleum products.

Thus, the final result η 'of identification will be obtained by normalizing the quantity η - dividing by δ

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This value η 'will be constant for a given type of oil or oil product and can serve as an indicator of the presence of gas inclusions in oil. If η increases and η 'increases accordingly, this indicates the presence of gas inclusions. In this case, this measurement is erroneous and a separate calibration must be carried out for oils with gas inclusions. Thus, by additionally measuring the influence of metal-containing particles, we refine the identification of the type of oil.

Before work, we first determine the dielectric constant of the dehydrated oil of this type, the value of which is stored in the memory of the computer.

Claims (1)

A method for determining the water content in oil or oil products in a pipeline stream, characterized in that the integrated electrical conductivity of the oil or oil product is measured at a specific frequency f ₁ and additionally the integrated electrical conductivity is measured at an operating frequency f ₂ (f ₁ <f ₂ ), temperature correction of the measured parameters is carried out , determine the ratio η of the complex values of the electrical conductivities at two different frequencies, determine the mass fraction of metal-containing microparticles δ, and by the value of the ratio η carry out the process with identification and largest ratio

refine the type of oil or oil product, and the total water content in the oil or oil product is calculated according to the calibration model related to this type of oil or oil product.

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