RU2417310C2 - Optimised procedure for supply of reagents into installation - Google Patents

Abstract

FIELD: oil and gas production. ^ SUBSTANCE: according to procedure flow is supplied via supplying pipeline into separator where flow is separated. De-foaming agent and de-emulsifier are metered depending on their effect to thickness of foam layer and emulsion layer, correspondingly, in flow. Measurement of emulsion and foam layers is performed with density profile gauge. This gauge sends a signal to a device controlling pumps operation, The pumps supply measured amount of de-foaming agent and de-emulsifier into flow subjected to separation. ^ EFFECT: raised efficiency of procedure. ^ 4 cl, 5 dwg

Description

Technical field

The present invention relates to a method for optimizing the use of reagents, in particular the use of antifoam agents and demulsifiers, in oil refineries on the seabed, on the seashore or on the high seas.

State of the art

Auxiliary chemicals, such as antifoam agents and demulsifiers, should almost always be used in oil refining, where the main operation is the separation of gas, oil and water.

To date, such auxiliary reagents are manually dosed using pumps that are installed in different places, based on the intensity of the platform and on the degree of difficulty with foaming and separation in the process, which are evaluated visually and individually, based on the current situation on the platform. The usual way to add auxiliary reagents is to adjust their dosage in case of difficulty. Often days pass between regulations. Psychologically, it is easier to increase the dosage in case of difficulty than to reduce it. Applicants have found that both a decrease and an increase in dosage by trial and error are optimal, and this operation is extremely difficult. As a result, a reagent company is often called up and, for example, this company finds a new reagent.

This practice is inaccurate and often leads to an overdose of auxiliary reagents, and reagents are often characterized as harmful to the environment.

The present invention provides a method of dispensing reagents, which is an accurate addition of reagents and, thus, reduces the cost of such reagents and saves the environment from unnecessary and harmful emissions.

Disclosure of the invention

The present invention, characterized in that the reagents are dosed, based on the effect that they exert on the thickness of the foam layer and the emulsion layer, respectively, of the liquid, is defined in the presented claims and is illustrated by drawings.

Description of drawings

Figure 1 is a graph illustrating a typical dependence of the achieved effect when dosing the reagent.

Figure 2 - diagram of the separation tank with a graph illustrating the formation of various layers in the tank.

Figure 3 - diagram of the implementation of the optimization method.

4 is a diagram of an alternative embodiment of the solution shown in figure 3.

5 is a graph of the dosage of reagents according to the method in accordance with the present invention.

To date, separators usually use only simple level and surface sensors plus temperature and pressure meters, for example, separators to separate water from oil.

However, in recent years, it has become more common to install one or more density profile meters, which, in addition to the liquid surface and the oil / water interface, also record the density profile through the separator. This provides quantitative information about the intermediate phases in the separator, such as the foam phase and the emulsion phase (see figure 2).

There are several principles that apply to commercial density profile meters:

Meters based on multi-level gamma radiation (sources and detectors).

Multilevel capacitance meters.

Meters based on multilevel induction measurement.

In addition to density profile meters, water cut meters, that is, meters that measure the amount of water in oil in an oil-water liquid stream, become part of the standard equipment for separators.

The fundamental idea of the present invention is to control the dosage of reagents, in particular antifoam reagents and demulsifiers, based on the effect that they have on the thickness of the foam layer and emulsion layer, respectively, in the separator.

Exposure to reagents is usually dosage dependent. Most regents have an “optimal” dosage, which produces the most significant effect at the optimization point, as shown in FIG. The vertical axis in figure 1 shows the effectiveness of the reagent, while the horizontal axis shows the dosage. As shown in Fig. 1, both an overdose and an insufficient dose have a reduced effect. Because of this, it is important to constantly dose the required supply of reagent.

Figure 2 shows a schematic gas / oil / water separator in which its contents may be, from top to bottom, gas, foam, oil, emulsion (water and oil) and water. To the right of the separator is a graph illustrating the relationship between the height and density of the various layers.

The claimed method consists in regulating the dosage of reagents, in particular antifoam reagents and demulsifiers, based on the effect that they exert on the thickness of the foam layer and the emulsion layer, respectively, in the separator. Figure 3 shows the implementation of the method of the present invention. Gas / oil / water is supplied to the separation tank 1 from a well or analog (not shown in FIG. 3) via a supply pipe 2. Various layers of gas, foam, oil, emulsion and water are formed in the tank. The measuring device 3 registers the state of the various layers and sends a signal to the control device 4, which, in turn, controls the pumps 5 and 6. These pumps pump the necessary amount of reagents (antifoam reagents and demulsifiers) from the tanks 7, 8 to supply the pipeline 2 through the pipelines 9, 10 based on the signals from the control device 4.

In accordance with figure 3, the benchmarks of the method of regulating the dosage of reagents may, for example, include:

- minimizing the thickness of the foam and emulsion layers, that is, maximizing the possible separation in the separator, based on the addition of reagents, and

- satisfying the maximum number of requirements for the thickness of the foam and emulsion layers, that is, minimizing the use of reagents, based on the separation ability of the separation system.

The method requires measurement, using a measuring device 3, of the density profile along the height of the separator, which shows the thickness of the foam and emulsion layers.

Figure 4 shows an alternative solution in which a water cut meter 11 is mounted on an exhaust pipe 14 for measuring the amount of water in the separated oil phase and an oil in water meter 12 is mounted on a discharge pipe 15 for measuring an oil concentration in the separated aqueous phase flowing from the separator 1. These measurements, for good advantage, can be introduced into the adjustment algorithms of the control device 4 in order to increase the accuracy of the control method.

Nevertheless, the actual dosages indicated for the antifoam reagent and demulsifier are constantly changing in proportion to the most important properties and parameters of the process, such as:

The chemical phase boundary (gas / liquid and oil / water interface) is the result of all surfactants in the oil and water phases. Auxiliary reagents such as shell inhibitors, hydrate inhibitors, paraffin inhibitors and corrosion inhibitors are all more or less surface active, and changes in their dosages affect the chemical composition of the gas / liquid and oil / water interfaces. In addition, the chemical composition is also affected by the water cut and the gas / liquid ratio in the process stream (since the concentration of the interface is the amount of surfactant separated by the phase boundary in the system). Other important parameters that affect the chemical composition of the phase boundary are system pressure, system temperature, and well composition (since oil composition may vary in the reservoir).

The phase boundary portion consists of gas / liquid and oil / water phase boundary portions, that is, the total volume of droplets and surface bubbles, respectively. The section of the phase boundary of the foam phase is also determined by the flow rate, the gas / liquid ratio and the size distribution of the bubbles. The phase boundary portion of the emulsion phase is also determined by the flow rate, water cut, and droplet size distribution.

The properties and parameters that determine the dosage required for antifoam agents and demulsifiers are numerous and very difficult (often impossible) to measure. As a result, the practice of manual regulation was previously introduced.

The proposed dosing method constantly optimizes the total effect of all parameters and properties, as described above, and the method according to the present invention, thus, ensures accurate dosing at any time.

The reagent savings in the case of applying the method according to the present invention can be significant, as proposed in FIG. 5, in which the graph shows the dosing during the oil / water separation over a period of time. The dashed line shows the addition of reagents, using the manual control method that is currently used, while the solid line shows the dosing in the corresponding process, using the method in accordance with the present invention.

Claims (4)

1. The method of optimizing the use of antifoam agent and demulsifier for gas / oil / water flows in oil refineries located on the seabed, on the seashore or in the open sea, in which the flow is fed through a supply pipe to a separator in which it is separated, characterized in that the antifoam agent and demulsifier are dosed based on the effect that they exert on the thickness of the foam layer and the emulsion layer, respectively, in the stream, and the measurement of emulsion and foam layers is performed using a meter rofilya density with which the signal fed to the control device that controls operation of the pumps providing the pumping metered quantities of antifoaming agent and demulsifier in the flow to be divided. 2. The method according to claim 1, characterized in that the antifoam agent and demulsifier are added to the supply pipe. 3. The method according to claim 1 or 2, characterized in that using the water content meter (11) on the exhaust pipe (14), the amount of water in the separated oil phase is measured, and the oil in water meter (12) on the exhaust pipe (15) is measured the concentration of oil in the separated aqueous phase flowing from the separator (1). 4. The method according to claim 3, characterized in that the measurement results of the meter (11) and the meter (12) are used for the adjustment algorithms of the control device (4) in order to increase the accuracy of the control method.

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