RU2376523C2 - Method to transport gas-oil-water mix and device to this effect - Google Patents

Abstract

FIELD: oil-and-gas industry.

SUBSTANCE: invention can be used in intrafield gas-oil-water mix transfer. Proposed method comprises preliminary treatment of said mix by demulsifier, and producing pressure and velocity phase divider in large-diametre pipeline to break the mix into phases to be enclosed in said phase divider. It includes also gas bleeding from gas-water interfaces at various level with the help of multiple independent flows. Gas-oil-water mix is forced consecutively, in said large-diametre pipe, through vortex electromagnetic field inductors and overflow cascade arranged on inclined section of aforesaid pipeline. Oil and water are directed from said enclosed spaces of phase divider are directed into separate separators. Note here that water is subjected to permanent electromagnetic field effect at phase divider outlet. Gas is bled from gas-water and gas-oil interfaces and fed into separator gas zones at various levels via multiple independent flows that feature sections decreasing in height, and forcing said gas into gas zone of subsequent apparatus. Gas from oil and water separators is also bled at various levels via multiple independent flows that feature sections decreasing in height and is forced through expanding tanks. Drop-like oil and water separated therein are continuously forced back into appropriate separators. Further on, gas is directed, via collecting gas duct, into final collecting tank. Water-oil condensate separated therein, as well as water ballast from oil separator bottom, are intermittently fed back into large-diametre pipeline, while water with settled mechanical impurities on water separator bottom is periodically bled for further recovery and use. Jump variation in pressure differences between separators and between enclosed spaces in phase divider is compensated by bypassing excess or deficient amount of gas from one enclosed space or separator into another. Proposed device comprises large-diametre pipe with its inlet accommodating vortex electromagnetic field inductors and its center, on inclined section, furnished with stepwise overflow cascade. The pipe outlet accommodates phase divider divided by webs into oil and water phase chambers communicated, via pipes, with oil and water separators, respectively. Gas zones of oil and water chambers in phase divider communicate, via multiple various-diametre pipes of gas bleeders, with oil and water separators' gas zones. Pipe arranged on phase divider water chamber outlet is furnished with permanent electromagnetic field inductors.

EFFECT: accelerated mix separation into phases, higher reliability of phase control, higher quality of phases.

2 cl, 1 dwg

Description

The invention relates to the oil industry and is intended for infield transport of gas-oil mixture.

A known method of transporting a gas-oil mixture through a pipeline, providing for its preliminary processing by a demulsifier, creating a discharge pressure in the pipeline and reducing the speed of the mixture at the final section of the pipeline to a value that ensures the separation of the mixture into phases, enclosing them in closed volumes, directing them to the appropriate separator compartments and gas sampling from the gas-water interface in the mode of self-regulation of the speed and pressure of the discharge, setting a certain speed the gas phase of the enclosed volume and the pressure difference between the separator and the end phase divider (CDP), which is proportional to this phase flow divider (AS №976214, IPC F17D 1/14, 1982 YG).

A device for its implementation includes a CDF, a separator with level controllers and outlet pipes. The device is equipped with a container connected to the CDF and the separator and divided by a vertical partition into sections, in the second of which, along the water, a gas sampling device is installed in the form of an inverted bowl connected by a nozzle to the gas cavity of the separator, the lower edge of the gas sampling device being installed below the upper edge of the partition, and the profiles the edges are sawtooth (the same source).

A disadvantage of the known method and device is that when pulsating fluctuations in the flow rate and pressure of the mixture in the pipeline occur, the quality of phase separation deteriorates due to the complexity of the regulation of their selection.

The closest in technical essence to the proposed one is a method of transporting a gas-oil mixture, including its preliminary treatment with a demulsifier, creation of a discharge pressure and flow velocity in a pipeline of large diameter and CDP, which ensure separation of the mixture into phases, their conclusion in a closed volume and gas selection from the gas interface and water at various levels through a multitude of autonomous flows with sections decreasing in height and entering it into the gas zone of the subsequent apparatus (AS No. 1.093.874, IPC F 17D 1/14, 1984).

A device for implementing this method includes a large-diameter pipe connected to a phase divider, and a separator, separated by partitions into closed volumes for oil and water, the gas zones of which are connected by a gas sampling device in the form of many tubes with sections decreasing in height, and inlet and outlet pipes ( same source).

Significant disadvantages of the known method and device are:

- insufficient rate of separation of the gas-oil mixture into phases in a large-diameter pipe on the way to the phase divider;

- insufficient accuracy of the control of phase selection in the subsequent apparatus after the CDF due to the unreliability of the regulation of liquid levels in the separator, which with constantly changing water and oil consumption, their viscosity, pressure and temperature can lead to unpredictable fluctuations in the levels of separated water and oil, their overflow through the separation barrier in the separator and mixing, gas entering the oil and water extraction lines, deterioration of the quality of the selected phases.

The objective of the invention is to provide a method for transporting a gas-oil mixture and a device for its implementation, which accelerate the separation of the mixture into phases, increase the reliability of the regulation of phase selection, improve the quality of the selected phases and reduce gas losses by evaporation.

This problem is solved by the proposed method of transporting a gas-oil mixture, including its preliminary treatment with a demulsifier, creation of a large diameter discharge pressure and flow rate in the pipeline, which ensure separation of the mixture into phases, their conclusion in a closed volume of KDF and gas selection from the gas-water interface at various levels by means of a multitude of autonomous flows with sections decreasing in height and entering it into the gas zone of the subsequent apparatus.

What is new is that the gas-oil mixture in a large-diameter pipe is successively passed through vortex electromagnetic field inductors and an overflow cascade in an inclined section of a large-diameter pipe, oil and water from the corresponding closed volumes of the phase divider are sent to separate separators, and water is subjected to exit the phase divider the influence of a constant electromagnetic field, the selection of gas from the gas-water and gas-oil boundaries in the phase divider and its supply to the gas zones of the separators is carried out at various levels by means of a multitude of autonomous flows with decreasing cross-sectional heights, gas from oil and water separators is also taken at various levels by a multitude of autonomous streams with decreasing cross-section heights and passed through expansion vessels, the droplet oil and water separated therein are constantly returned to the corresponding separators, then the gas is sent through a combined gas pipeline to the final expansion tank, the oil-water condensate separated in it, as well as the water ballast from the sep bottom Atomizer for oil is periodically introduced back to the inlet of large-diameter pipes, and water with settled mechanical impurities from the bottom of the water separator through the sump is periodically taken for further disposal and use, an abrupt change in the pressure drop between the separators, as well as between closed volumes in the phase divider, compensate for bypassing the missing or excess amount of gas from one separator or a closed volume to another.

The proposed method for transporting a gas-oil mixture is carried out using a device including a large diameter pipe connected to a phase divider, and a separator separated by partitions into closed volumes for oil and water, the gas zones of which are connected by a gas sampling device in the form of a plurality of tubes with sections decreasing in height, and inlet and outlet pipes.

New is that the large-diameter pipe at the inlet is equipped with vortex electromagnetic field inductors and an overflow cascade in the form of oblique steps with undulating surfaces on the inclined section of the large-diameter pipe, then again turning to a straight section and ending with a phase divider in which the partition separating the oil and the water zone, completely overlaps its upper section and forms separate gas cavities; the device is equipped with separate separators for oil and water, and the gas zone of the first of them is connected by a gas sampling device in the form of a plurality of tubes of variable cross section to a gas cavity of a closed volume for an oil phase divider, and the gas zone of the second is connected by a similar gas sampling device to a gas cavity of a closed volume for water of a phase divider while the separate gas cavities of the phase divider, as well as the gas zones of the separators, are interconnected by transfer pipes with valves; a pipe connecting the closed water volume of the phase divider to the water separator is covered by inductors of a constant electromagnetic field; the separators are equipped with gas sampling devices in the form of many tubes with cross sections decreasing in height, each of which is connected to an expansion tank with a condensate return pipe to the corresponding separator, and the separator expansion tanks are connected via gas pipelines to the final expansion tank with an oil-water condensate signaling device in it, which the pipe is connected to the inlet to the large-diameter pipe and to the outlet from the bottom of the oil separator with an indicator of the presence of water in it ballast for periodic discharge of condensate and ballast back to the inlet of a large diameter pipe; the separator for water in the bottom is equipped with a sump with an indicator of the presence of water in it with mechanical impurities.

The drawing shows a schematic diagram of the proposed method for transporting a gas-oil mixture and a device for its implementation.

The device includes a horizontal pipe of large diameter 1, at the input of which inductors of a vortex electromagnetic field 2 are installed, and on an inclined section of the pipe 3, an overflow cascade in the form of shelves slanted with the undulating surfaces of surfaces 4. Next, the pipe again switches to a straight section and ends with a phase divider 5, at the outlet of which the water flow is swept by the inductors of a constant electromagnetic field 6. The phase divider is divided by partitions 7 and 8, forming a box for oil 9, and a partition 10, which is a water seal and forming a closed volume for water 11. The partition 8 divides the upper zone of the phase divider into two gas cavities 12 and 13. The box 9 with a pipe 14 is connected to a separator for oil 15, and a closed volume 11 with a pipe 16 is connected to a separator for water 17. The separator 15 is equipped a partition 18, and a separator 17 - a partition 19. Separate gas cavities 12 and 13 of the phase divider are connected to the gas zones of the separators 15 and 17 by gas sampling 20 in the form of a plurality of tubes of variable cross-section with ends in the phase divider located at different levels. The separators 15 and 17 and the separate gas cavities 12 and 13 in their upper parts are connected bypass pipes 21 with valves 22. The separators are equipped with gas sampling devices 23 in the form of a plurality of tubes of variable cross section, the ends of which are connected to expansion tanks 24 with nozzles 25 for draining at the outlet of the separators condensate from a drop of oil or water into an appropriate separator. The expansion tanks by nozzles 26 and a common gas pipeline 27 are connected to the final expansion vessel 28, equipped with an alarm 29 of the presence of oil-water condensate in it and a pipe 30 connected to the entrance to the large diameter pipe 1. The lower zone of the separator 15 through the pipe 31, equipped with an alarm 32, is connected with pipe 30, which, as the accumulation of oil and water condensate in the tank 28 or water ballast in the bottom of the separator 15 allows you to periodically return them to the inlet of the pipe of large diameter 1.

The method is carried out in the following sequence. The gas-oil mixture, pre-treated with a demulsifier, which helps to weaken the surface tension of small particles of the emulsion, enters the pipe of large diameter 1, which creates favorable conditions for phase separation of the mixture by reducing the speed and calming the flow in it. At the entrance to the pipe 1, the mixture passing between the inductors 2 undergoes intensive bubbling, i.e., the release of electrically charged emulsion particles from the gas microbubbles enveloping them, which prevent the homogeneous particles of the emulsion from merging due to their shaking by the vibrational effect of the vortex electromagnetic field. When passing through the overflow cascade 4, the mixture undergoes intensive flotation and separation and further degassing due to the effective hydraulic friction of the drops of the freely falling mixture with the drops of the mixture flowing longitudinally along the shelves of the overflow cascade, repeatedly intersecting in a slightly turbulent mode, selected by the height of the steps of the cascade relative to each other, contributing to the fastest enlargement, ascent and immersion, depending on the specific gravity of the globules, and the merging of homogeneous drops into separate Wow phases.

Having reached the phase divider 5, the flow of the stratified mixture is divided into flows of oil, gas and water. The latter, after exiting the phase divider, passes between the inductors of a constant electromagnetic field 6. The oil flow overflows through the baffle 7 and enters the box 9, where from under the influence of a pressure drop

. При изменениях расхода фаз уровни воды и нефти в объемах 11 и 9 колеблются и перекрывают те или иные трубки 20. Расход продукции скважин может колебаться в пределах ±(0-50)%. Диаметры и длины трубок подбираются таким образом, что при расходе Q=Q_ср открыты лишь часть трубок (около 70% из них). С уменьшением расхода газа давления P₁ и Р₃ уменьшаются, уровни жидкости в отсеках делителя фаз поднимаются и перекрывают часть трубок 20, оставляя открытыми трубки меньшего диаметра. Отбор газа из делителя фаз резко уменьшается, давления P₁ и P₃ начинают вновь расти и это происходит до тех пор, пока исходные давления ΔP₁ и ΔР₂ не восстановятся и не прекратится подъем уровней нефти и воды. С увеличением расхода газа (при увеличении дебита и газового фактора подключаемых скважин) давления P₁ и P₃ растут, как и напоры ΔP₁ и ΔР₂, уровни воды и нефти опускаются, открывая трубки 20 большего диаметра. Отбор газа из делителя фаз резко возрастает, давления P₁ и Р₃ быстро стравливаются, пока не восстановятся исходные перепады давления ΔP₁ и ΔР₂. Такое перекрытие и открытие последовательно изменяющихся в диаметре по высоте отбора газа трубок 20 обеспечивает постоянство уровней воды и нефти в пределах высоты "h" во всем диапазоне колебаний расхода фаз.ΔP ₁ = P ₁ -P _{2 is} sent through the pipe 14 to the oil separator 15. The water flow passes under the bottom of the box 9 and overflows through the partition 10 into a closed volume 11. The height of the partition 10 with respect to the partition 7 is selected by calculation. The flow of water from the volume 11 through the pipe 16 under pressure ΔР ₂ = Р ₃ -Р _{4 is} directed to the water separator 17, passing through the power lines of a constant electromagnetic field 6, which contributes to the electric and magnetic charging of particles of mechanical impurities of water, their mutual attraction, enlargement and loss in the sediment in the form of flakes in the separator 17 and clarification of commercial water. The pressure drops ΔP ₁ and ΔP ₂ are formed when gas passes through many tubes of different cross-sections of the gas samplers 20, which take gas by autonomous flows from the gas cavities 12 and 13 near the boundaries of the gas-water and gas-oil volumes of the phase divider. The pressure loss in the tubes is inversely proportional to their diameter to the fifth degree

. With changes in the flow rate of the phases, the water and oil levels in volumes 11 and 9 fluctuate and overlap one or another pipe 20. The flow rate of well production can fluctuate within ± (0-50)%. The diameters and lengths of the tubes are selected in such a way that at a flow rate of Q = Q _cf only a part of the tubes are open (about 70% of them). With a decrease in gas flow, the pressures P ₁ and P ₃ decrease, the liquid levels in the compartments of the phase divider rise and block part of the tubes 20, leaving the tubes of a smaller diameter open. The gas extraction from the phase divider decreases sharply, the pressures P ₁ and P ₃ begin to rise again, and this happens until the initial pressures ΔP ₁ and ΔP ₂ are restored and the rise in oil and water levels stops. With an increase in gas flow (with an increase in flow rate and gas factor of connected wells), the pressures P ₁ and P ₃ increase, as do the pressures ΔP ₁ and ΔP ₂ , the water and oil levels drop, opening tubes 20 of larger diameter. The gas extraction from the phase divider increases sharply, the pressures P ₁ and P _{3 are} quickly released until the initial pressure drops ΔP ₁ and ΔP ₂ are restored. Such overlapping and opening of the tubes 20, successively varying in diameter along the gas extraction height, ensures constant water and oil levels within the height "h" in the entire range of phase flow fluctuations.

Similar processes for regulating pressure, level and phase selection occur in the separators 15 and 17 due to the presence of their own gas samplers 23 with tube sections varying in height of sampling and regulation of pressure and liquid level within the height "h".

Possible spasmodic changes in the pressure difference between the separators and between the closed compartments for oil and water in the phase divider, for example, when turning on and off certain groups of wells, are compensated by transferring the missing or excessive amount of gas from one separator or closed volume to another by means of overflow pipes 21 with valves 22. All gas received from the phase divider into the separators 15 and 17, a lot of autonomous flows through the nozzles of the gas sampling 23 comes under the influence of pressure drops ΔP ₃ = P ₂ -P ₅ and ΔP ₄ = P ₄ -P ₆ into expansion vessels 24, where particles of droplet oil or water merge and return them in the form of oil or water condensate through nozzles 25 to the respective separators. Gas from containers 24 under the influence of pressure drops ΔP ₅ = P ₅ -P ₇ and ΔP ₆ = P ₆ -P ₇ through the nozzles 26 and the common gas pipeline 27 is sent to the final expansion tank 28, equipped with a signaling device 29 of the presence of condensate from the drip oil in it and water. The condensate through the pipe 30 is connected to the ballast water flowing through the pipe 31 through the signaling device 32 from the bottom of the separator 15. From time to time, the oil-water condensate and the ballast water are sent in small portions as they accumulate back to the pipe inlet 1. Water purified from oil from the separator 17 under the pressure P _{4 is} sent to the consumer through a pipe 33 with a valve 34, designed to adjust the water level in the separator 17 within the height "h", which is especially important when commissioning the phase divider. Oil purified from water from the separator 15 under pressure Р _{2 is} sent to the consumer through the oil pipeline 35 through the control and adjustment valve 36. Gas, having passed the expansion tank 28 and got rid of the oil-water condensate, is supplied to the consumer through the pipeline 37 under pressure Р ₇ . Water with mechanical impurities as they precipitate and accumulate in the sump 38 of the separator 17 through the signaling device 39 through the pipe 40 is periodically taken for further disposal, extraction of useful substances using various physicochemical methods and the final cleaning of commercial water from mechanical impurities.

The positive effect of using the proposed method and device is:

- accelerated stratification of the gas-oil mixture into phases, which is achieved by bubbling electrically charged particles of water and oil in a vortex electromagnetic field, releasing them from armor shells from gas microbubbles, preventing the merging of homogeneous globules of oil and water, bypassing the mixture through an overflow cascade using the effect of close hydraulic contact , flotation, separation and intensive merging of homogeneous particles and layers of the emulsion, processing the flow of separated water with mechanical impurities in a constant electromagnetic field, which contributes to the electrical charging of impurity particles, magnetic polarization, mutual attraction, enlargement and precipitation, which positively affects the clarification of water, the preservation of the injectivity of the wells into which bottom-hole purified water is pumped;

- increasing the quantity and improving the quality of the selected gas as a result of two-stage purification of it from condensate and deep separation, which helps to reduce gas loss by evaporation in subsequent apparatuses due to a decrease in the gas factor of oil;

- stable and reliable regulation of the processes of separation and selection of phases, from the beginning to the end, proceeding in the automatic mode of regulation, preventing the mixing of already selected phases;

- the possibility of the complete elimination of many multi-ton and expensive, in the hundreds of cubic meters each, slopted steel bullets by replacing them with one phase divider and, most importantly, the possibility of reducing the size of the phase divider by 2-3 times, making it more compact and convenient for management, ecologically less impacting the environment;

- the possibility of extracting useful substances using various physicochemical methods, for example, electroplating, sintering and diffusion, from commercial water saturated with precipitates of mechanical impurities and ions of dissolved polymetals, which today are useless literally flowing through the hands of oilmen and which metallurgical and electronic industry and energy, which can bring a huge additional economic effect due to the cheapening of the extraction of related useful substances instead of expensive and destroy open-pit mining of mineral ores by open methods;

- improving the culture and aesthetics of production in the preparation of oil, gas and water, which, thanks to the full automation of production, can occur without the participation of a person who has only control and observational functions.

Claims (2)

1. A method of transporting a gas-oil mixture, including its preliminary treatment with a demulsifier, creation of a large-diameter pipeline of the pressure phase divider and flow rate, which ensure the separation of the mixture into phases, their conclusion in a closed volume of the phase divider and gas extraction from the gas-water interface at different levels by means of a multitude of autonomous flows with sections decreasing in height and introducing it into the gas zone of the subsequent apparatus, characterized in that the gas-oil mixture in a large-diameter pipe consequently pass through the inductors of the vortex electromagnetic field and the overflow cascade on the inclined section of the large-diameter pipe, oil and water from the corresponding closed volumes of the phase divider are sent to separate separators, and the water at the outlet of the phase divider is subjected to a constant electromagnetic field, gas is taken from the gas boundary water and gas-oil in the phase divider and its supply to the gas zones of the separators is carried out at various levels through a variety of autonomous flows with decreasing height from cross-sections, gas from oil and water separators is also taken at various levels by means of a multitude of autonomous flows with sections decreasing in height and passed through expansion tanks, droplet oil and water separated in them are constantly returned to the respective separators, then gas is sent through a collection gas pipeline in the final expansion tank, the oil-water condensate separated in it, as well as the water ballast from the bottom of the oil separator, periodically they are introduced back into the pipe inlet diameter, and water with settled mechanical impurities from the bottom of the water separator through the sump is periodically taken for further disposal and use; the sudden change in pressure drop between the separators, as well as between the closed volumes in the phase divider, is compensated by the transfer of the missing or excess amount of gas from one separator or the closed volume to another. 2. A device for transporting a gas-oil mixture, including a large-diameter pipe connected to a phase divider, and a separator, separated by partitions into closed volumes for oil and water, the gas zones of which are connected by a gas sampling device in the form of a plurality of tubes with sections decreasing in height, and outlet pipes characterized in that the large-diameter pipe at the inlet is equipped with vortex electromagnetic field inductors and an overflow cascade in the form of obliquely arranged steps with undulating on the inclined section of a large-diameter pipe, then again turning to a straight section and ending with a phase divider, in which the partition separating the oil and water zones completely overlaps its upper section and forms separate gas cavities; the device is equipped with separate separators for oil and water, and the gas zone of the first of them is connected by a gas sampling device in the form of a plurality of tubes of variable cross section to a gas cavity of a closed volume for an oil phase divider, and the gas zone of the second is connected by a similar gas sampling device to a gas cavity of a closed volume for water of a phase divider, in this case, the separate gas cavities of the phase divider, as well as the gas zones of the separators, are interconnected by transfer pipes with valves, a pipe connecting the closed water volume of the del a phase body with a water separator, covered by inductors of a constant electromagnetic field; the separators are equipped with gas sampling devices in the form of many tubes with cross sections decreasing in height, each of which is connected to an expansion tank with a condensate return pipe to the corresponding separator, and the separator expansion tanks are connected via gas pipelines to the final expansion tank with an oil-water condensate signaling device in it, which the pipe is connected to the entrance to the large-diameter pipe and to the outlet from the bottom of the oil separator with an indicator of the presence of water in it allasta for periodic discharge of condensate and ballast back into the large diameter tube; the separator for water in the bottom is equipped with a sump with an indicator of the presence of water in it with mechanical impurities.

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