RU2307977C1 - Method of batching reagent-demulsifier - Google Patents

Abstract

FIELD: oil industry.

SUBSTANCE: method comprises batching reagent-demulsifier in accordance with the flow rate and water content of crude oil that are determined from the formula proposed.

EFFECT: simplified method.

2 dwg

Description

The proposal relates to the oil industry, in particular to methods for dispensing reagents when transporting highly watered oil using a booster pump station (BPS), which has a separation unit in front of the pumps.

A known method of dispensing a reagent-demulsifier, in which half of the norm of the demulsifier is supplied to the collection system, and half to the oil preparation unit (see patent RU No. 2153382 C1, 7 B01D 17/04, BI No. 21 dated 07.27.2000).

The disadvantage of this method is the normalization of the flow rate of the demulsifier and the fixed ratio of the amount of demulsifier supplied to the collection system to the amount of demulsifier supplied to the oil treatment unit.

The closest in technical essence and the achieved results to the proposed one is a method for dosing a reagent for consumption and watering of crude oil (see Kuznetsov V.Ya., Rodigina EF, Latifullin RN. System for the automatic preparation and dosing of surfactants on oil treatment plants // Automation and telemechanization of the oil industry, 1975, No. 4, pp. 8-10).

The disadvantage of this method is not to take into account the separation of the emulsion in the oil collection system, as a result of which the cost of transportation is too high.

The technical task of the proposed method is to reduce the total cost of the demulsifier and electricity by achieving the optimal degree of separation of the emulsion in the oil collection system due to the optimal dosage of the reagent demulsifier.

The stated technical problem is solved by the described method of dosing the demulsifier reagent, in which the flow rate of the demulsifier is determined by the flow rate and water content of the crude oil.

New is that they additionally measure the relative volume of water W ₀ released in the separation unit and determine its control value W _{0, C} by the formula:

Where

W - water cut of crude oil, volume fractions;

C, B are empirical constants,

then change the flow of the metering pump in accordance with the formula:

Where

S - feed metering pump, l / h;

Q is the volumetric flow rate of the liquid to the separation unit, m ³ / s;

ρ _n , ρ _d - density of anhydrous oil and demulsifier, kg / m ³ ;

A, β, n are empirical coefficients.

Figure 1 shows a diagram of the collection of oil. Figure 2 shows the dependence of costs on the degree of separation of the emulsion in the separation unit.

The method is carried out in the following sequence.

At the next filling of the separation unit and subsequent pumping of the liquid, the value of the parameters (Q), (W) and (W ₀ ) are measured. The control value W _{0, C is} calculated by the formula (1) and then, by the formula (2), the feed value of the metering pump is calculated. Set the operation mode of the metering unit in accordance with the found value of the metering pump supply until the next time the separation unit is filled and the liquid is pumped out of it. Then perform a new measurement of the parameters and determination of a new value (S). In accordance with the new value (S), the dosage regimen is changed, etc.

An example of a specific implementation.

The oil collection system operates as follows (see Figure 1). After the demulsifier is fed with a BR-2.5 type metering unit 1 to gas supply unit 2, the gas-oil mixture in an amount of 600 m ³ / day via pipeline 5 with a length of 4000 m and an inner diameter of 150 mm is fed to a separation unit (buffer tank-separator 8 with a volume of 200 m ³ ) . In addition, crude from the demulsifier oil comes from GZU 3 and GZU 4 through pipelines 6 and 7 in the amount of 300 m ³ / day. The average daily volume of liquid flowing in three directions to the CSN is 900 m ³ (0.0104 m ³ / s) with a volumetric water content of 85%. After the separation of the gas-oil mixture into phases in the buffer tank-separator, the gas is sent through a separate pipeline (not shown in Fig. 1) to the sulfur treatment plant, and the liquid is pumped out by the pump unit 9. The pump of the CNS 180-297 brand is switched on when the liquid reaches the upper limit level and turns off when the liquid level drops below the minimum set. After the pump, the pumped liquid passes through the metering unit 10, where pressure, fluid flow rate and water content are measured. Further, the liquid is transported through pipeline 11 with a diameter of 250 mm, a length of 14420 m and a height difference between the end points of 200 m to an oil treatment unit (UPN) 12. The density (viscosity) of oil and water at 20 ° C is 880 and 1070 kg / m ³ ( 20 and 1.34 MPa · s), the density of the demulsifier is 940 kg / m ³ . Based on the results of studies conducted at this facility, it was found (see Figure 2) that the energy consumption 2 for pumping liquid from the BPS to the UPN decreases in proportion to the relative volume of water released in the buffer tank separator (W ₀ ) with a proportionality coefficient ( B), equal to 938.1. The coefficient (C) is determined from the dependence of the cost of the demulsifier (3 _dem ) on the degree of separation (W ₀ ), represented by curve 1 in Figure 2 and described by formula (3):

From this dependence, the optimal values of parameters (n) and (C) are n = 2 and C = 217. Total costs 3 are minimal when the degree of bundle W _{0, C} , calculated by the formula (1). According to the results of laboratory studies, the value of parameter (A) was determined, which reflects the effectiveness of the demulsifier and the characteristics of the destructible emulsion: A = 100. The parameter (β) characterizes the degree of correction of the supply of the demulsifier. Its value is established empirically based on the analysis of changes in the magnitude (S) and the difference W _{0, C} -W ₀ . The correction value should be within (3-30%) of the value (S). Initially, in the absence of the necessary data, the value β = 1.0 is assumed.

Based on the properties of this object, the method is carried out in the following sequence.

After the next filling of the buffer tank-separator 8 (see Figure 1) and pumping liquid out of it, measurements showed that 110 m ^{3 of} liquid was pumped out, including water was 88 m ³ . This corresponds to the value of W ₀ = 0.80. Calculate according to the formula (1) the control value W _{0, C} : W _{0, C} = 0.73. With this degree of separation of the emulsion in the buffer tank-separator 8, the variable part of the cost of pumping liquid will be minimal (see Figure 2). Calculate the value (S) by the formula (2): S = 0.43 l / h. Carry out a change in the dosing regime of the dosing unit 1. After filling the buffer tank-separator 8 and pumping out the liquid, the new value of the relative volume of water released in the buffer tank-separator (W ₀ ) turned out to be 0.77. At the same time, the flow rate of fluid entering the CSN decreased to 0.0097 m ³ / s or 838 m ³ / day. The proportion of water in it decreased to 0.84. For new conditions, the calculations give values of W _{0, C} = 0.72 and S = 0.46. Make a change in the dosage regimen of the dosing unit 1. Subsequent changes in the dosage regimen are carried out similarly to the above.

The data on total costs showed a decrease in the cost of the demulsifier and the energy consumed by the pump unit in the proposed specific example by 106 thousand rubles / year (the proposed method - 717 thousand rubles / year; prototype - 823 thousand rubles / year), which is 12 ,9%.

Using the proposed method of dispensing a reagent-demulsifier can reduce the total cost of a reagent-demulsifier and electricity by 10-20%.

Claims (1)

A method for dispensing a demulsifier reagent by flow rate and water cut of crude oil, characterized in that it additionally measures the relative volume of water W ₀ released in the separation unit and determines its control value W _{0, C} by the formula

where W is the water cut of crude oil, volume fractions; C, B are empirical constants, then change the flow of the metering pump in accordance with the formula

where S is the feed of the metering pump, l / h; Q is the volumetric flow rate of the liquid to the separation unit, m ³ / s; ρ _n , ρ _d - density of anhydrous oil and demulsifier, kg / m ³ ; A, β, n are empirical coefficients.

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