RU2454262C2 - Method of separating oil-water-gas mix from oil wells and four-product sump to this end - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention relates to separation of oil well products into fractions: oil, emulsion, water and gas. Proposed method comprises: cycle of simultaneous accumulation, settling and collection of products in three volumes settled along vertical and confined by product interfaces, i.e. oil and water-oil emulsion with water and gas residues, water with oil and gas residues. Oil, emulsion, water and gas as-collected are extracted and discharged separately and at different times. Alternating discharge of one of fluids with that of gas and vice versa is performed by shutting off gas flow fluid product or releasing it after termination of preset amount of fluid product. Product is identified by measuring density of fluid products. Four-product sump comprises vertical cylindrical housing with inlet and discharge unions, appliances for settling product extraction, plates, drop catcher made up of hydraulic cyclone with drain pipe confined by vaned plates confined from below. Appliances for extraction oil, emulsion and water are made up of bellows with gate valves. Sump includes computation unit connected with transducers.

EFFECT: higher process efficiency.

2 cl, 1 dwg

Description

The invention relates to methods and devices for separating oil well products into fractions and can be used in the preparation of products in the field for supplying it to the product park or preparing it before distillation in an oil refinery, as well as for use in the separation processes of any mixture of liquids with different densities into fractions and gas with subsequent measurement of their volume and mass.

A known apparatus for oil dehydration (patent RU No. 2077918 C1 of 04/27/97, IPC: B01D 17/28) containing a horizontal cylindrical body with transverse partitions arranged in series in its middle part, the upper and lower edges of which are stepwise shifted down alternately and consecutive increase in displacement in the direction of exit, a pipe for supplying an oil-water mixture, pipes for draining gas, water and oil, a compartment for oil dehydration, oil and water level regulators, the amount of displacement and the number of partitions being determined wearing the densities of oil and water. The method of oil dehydration carried out by the apparatus includes: supplying a given oil-gas mixture with a predetermined flow rate, continuously separating it into gas and liquid phases, separating the liquid phase into oil, emulsion, water and gas by multiple sedimentation, alternately and sequentially, of the mixture volumes in the compartment in front of each partition, and oil settled in the upcoming compartment with residual water cut and gas saturation constantly replenishes the volume in the subsequent compartment, from where the water constantly goes down; selection of settled oil with residual water cut and gas from the upper thin surface layer of each mixture volume in the next compartment by overflow through the top of each partition into the subsequent compartment; intensification of the separation process during overflow; passing the emulsion under the bottom of the partition into the subsequent compartment, taking water from the lower layer of the volumes of the mixture and passing it under the partitions to discharge, then accumulating dehydrated oil and emulsion, with its level regulation, in the last compartment and regulating the water level in the compartments; drainage of dehydrated oil, emulsion, water and gas to the consumer.

The disadvantages of the known apparatus and method are:

- the limited capacity of the apparatus, due to the fact that its dimensional parameters are calculated strictly for certain ratios of the densities of oil and water and the flow rate of the mixture;

- multistage overflow from compartment to compartment of oil mixed with water residues provokes additional formation of a water-oil emulsion by mixing the top layer of oil in the compartment with an overflowing jet;

- the emulsion is not separated from the oil;

- the sludge oil in the compartments is ineffective, because of its short duration, due to the continuity of the dehydration process, and because of the constant disturbed equilibrium state of the oil by overflowing the mixture with unseparated water from the previous compartment, and for the same reason, the selection of oil from the near-surface oil layer in the compartment is irrational .

A device for the separation of oil, water and gas (a / c SU No. 1450840 A1 from 01/15/89, IPC: B01D 17/02; 19/00), containing a vertical cylindrical body with fittings for the inlet of flooded and gas-saturated oil, oil release , water and gas, plates, devices for removing oil, water, droplet eliminator, drain pipe, level sensors.

The method for the separation of oil, water and gas, carried out by the device, comprises: a constant value supply of water-cut and gas-saturated oil, its constant separation into liquid and gas phases, continuous release of the latter from the device with simultaneous cleaning of liquid droplets and their disposal, constant separation watered and residually saturated with gas oil to water, gas and the actual oil with emulsion multiple sludge, alternately and sequentially, a series of vertical volumes of sedimented oil, constantly replenished about stand oil from water and residues of gas from the upper volume, where constantly removed to release water downward and upward gas, and the selection of the settled oil comprises residual water and gas from the top of the surface layer of the next volume and an outlet in the bottom, the regulation of the level of oil and water.

The known method and device have disadvantages:

- inefficiency of the sludge process due to its short duration, due to the continuity of the process of receipt from volume to volume of its products and their release from the apparatus;

- constant and repeated mixing of oil by discharge from above from volume to volume provokes the formation of an emulsion, in addition to the existing one;

- there is no selection of emulsions separately from oil;

- limiting the ability of the device, due to its ability to work only with one mode of oil supply.

The known method and device are closest in technical essence and the achieved technical results of the claimed invention.

An object of the invention is: increasing the efficiency of the process of sludge of oil and gas mixture from oil wells due to the discrete nature of the method, by dividing it into cycles: the cycle of accumulation and sludge mixture, collecting products of sludge in separate volumes, and a cycle of discrete discharge of accumulated products of sludge to the consumer, separately each product as collection is complete; expanding the capabilities of the method and device, expressed in their ability to function in the mode of changing the densities of the fractions of the mixture, the values of its supply, and separately collecting and discretely dumping the oil-water emulsion, as well as creating conditions that prevent the formation of an emulsion in addition to the existing one, measuring volumetric flows and densities of separation products.

The technical problem of the method of separation of oil and gas mixture from oil wells, containing a constant supply of the mixture, its constant separation into liquid and gas phases, discharge of the latter to the consumer with the simultaneous capture of droplets of the liquid phase and their disposal, the constant separation of the mixture into water, gas, oil with emulsion multiple sedimentation of a series of vertical volumes of the mixture, replenished with emulsion, oil, gas from the forthcoming volumes, from where water is removed down and gas upstream to the consumer, selection of settled oil from the emulsions water, regulation of oil levels with an emulsion, water, is solved according to the invention in that the method consists of a cycle of simultaneous accumulation and sedimentation of a settled mixture and collection of its products in a vertical column, according to density, and limited by inter-product interfaces, three volumes: oil and water-oil emulsion with water and residues of gas, water with residues of oil and gas, the value of which (residues) is inversely proportional to the sludge directly proportional to the ratio of the volume mixture advocated its debit - V _cm / Q _m and a minimum of only limited solubility residues in sludge products; a discrete cycle of selection and discharge to the consumer separately and at the same time of oil, emulsion, water and gas upon completion of their collection, separately and at the same time, each liquid product in a predetermined quantity, and alternating the discharge of one of the liquid products with the discharge of gas and vice versa, by shutting off the gas stream with the liquid product or releasing it at the end of the selection of a given amount of liquid product, while measuring: the density of the liquid products, the temperature of the gas phase and its pressure, the value of which is maintained in predetermined limits, volumetric flow rate of separation products; and limit the level of accumulated liquid products by dumping them to the consumer.

The technical problem of a four-product sump containing a vertical cylindrical body with inlet and outlet fittings, devices for selecting sludge products, a drip trap, drain pipe, level sensors, plates, is solved according to the invention in that the droplet eliminator is made in the form of a hydrocyclone, with a tangential inlet fitting, with a drain pipe bounded from below by plates with straightening vanes, an outlet fitting connected by a gas line equipped with pressure and temperature sensors, with a hydraulic lock, with common, in turn, with an exhaust line equipped with a measuring section and hydrostatic sensors of the upper and lower levels, with a combined volumetric flow meter and, further, with a discrete bypass valve, by magnetic locking of the extreme positions connected by the output to a common collector, as well as a discharge line equipped with devices for the selection of oil, emulsion, water, made in the form of siphons, and the siphons for the selection of emulsion and water are equipped with hydraulic locks, in addition, the sump includes a calculation unit and connected with pressure sensors, temperature, level and combined volumetric meter.

The essence of the invention is illustrated in the drawing. The four-product sump (hereinafter referred to as the "Sump") consists of a vertical cylindrical body 1 with a cover 2, in which a drop catcher 3 is made, made in the form of a hydrocyclone 4 with a tangential inlet fitting 5, a cone 6, a drain pipe 7, an annular pipe 8 bounded from below, and a bottom 9 plates with straightening shovels 10, forming diffuser interscapular channels 11, giving the flow a radial direction and inhibiting it. On the cover 12 of the hydrocyclone 4 there is an outlet fitting 13 connected by a gas line 14, equipped with pressure sensors DD 15 and temperature DT 16, with a hydraulic lock 17, in the form of a tee 18 with two inputs 19, 20 and one output 21 connected by an exhaust line 22, equipped vertical measuring section 23, with sensors of the lower DNU 24 and upper TLD 25 levels at the ends of the section 23 at a distance of H ₀ , with a combined volumetric flow meter 26. The counter 26, further communicated with the bypass spring-loaded valve 27 discrete action, by magnetically locking the extreme positions of the valve 27: "Open" and "Closed". The hydrostatic sensors of DNUs 24 and 25 of the TLD level are connected by a surge line 28 to gas line 14. Valve 27 is connected by an output to a common collector 29. Input 19 of the hydraulic lock 17 is connected to a discharge line 30 equipped with devices in the form of siphons for sampling: oil 31, oil-water emulsion 32, 33. The water siphon 32 and siphon selection emulsion 33 for the selection of the water hydraulic locks equipped _3.E h, h _3.B 34, 35 serving to prevent access of oil into the siphon 32 and siphon emulsion access sump 33. The composition included unit calculation BR 36 associated with sensors d the occurrence of DD 15 and temperature DT of the gas phase, level sensors DNU24, DVU 25 and counter 26. To collect the separation products, three are used alternately, separated according to the vertical density, volumes separated by inter-product interfaces: oil 37 and oil-water emulsion 38 with water residues and gas, water 39 with residual oil and gas.

A method of separating an oil-gas mixture from an oil well is carried out discretely by a sump as follows: in a cycle of simultaneous accumulation and sludge of a mixture, collection of its products, the mixture is constantly fed through a tangential inlet fitting 5 to a hydrocyclone 4, where it is produced in a centrifugal field in a rotational movement of the mixture flow along the walls separation of the liquid and gas phases, including trapping droplets of the liquid phase in the gas part of the rotating mixture stream and their disposal in the liquid part of the stream. The gas phase through the exhaust nozzle 13 is removed through the gas line 14 to the common manifold 29. The liquid phase flowing down the walls through the cone 6, where its rotation speed increases and the final phase separation occurs in the hydrocyclone 4, is fed under the accumulated pipe 7 under the surface of the accumulated in the housing 1 of the liquid phase, which prevents the destruction of the current state of the upper layers of settled products. First, the liquid phase passes through the diffuser interscapular channels 11, where its rotating flow acquires a radial direction and reduces the velocity to a value characteristic of a non-pressure fluid flow, thereby preventing intensive mixing and turbulization of the entire volume of the accumulated liquid phase, which disrupt the sludge process.

In the cycle of simultaneous accumulation of the mixture, its sludge and collection of its products, the constantly entering liquid phase from cyclone 4 is mixed with the remaining gas phase to the volume of the previously accumulated liquid phase, its constant separation in the gravitational field by the remainder of the gas rising through the liquid upward, and removing it through a discharge line 30 to a common collector 29, to water flowing down through all layers of the liquid phase, to a water-oil emulsion rising up through all layers of water and finally to oil, also rising up through Loi water emulsion.

The collection of separation products is carried out in a series of three, settled according to the vertical density, volumes separated by inter-productive section surfaces: oil 37 and oil-water emulsion 38 with the remains of water and gas, water 39 with the remains of oil and gas. The values of these residues are inversely proportional to the settling time, which is directly proportional to the ratio of the volume V _{cm of the} settled mixture to its flow rate Q _cm : V _cm / Q _cm ; and their minima are limited by the solubility of residues in sludge products. Along with the ongoing sludge process, there is a process of separation and collection of sludge products. Through the water-oil interface, lower 39 with water and middle 38, with emulsion, there is a constant movement of residues: down water, collecting and accumulating it in the lower volume 39, up oil, emulsion and gas. Through the emulsion-oil interface, an average volume of 38 with the emulsion and the top 37 with oil, the residues are constantly moving: down water, up oil and gas; and collecting and storing the emulsion in an average volume of 38.

Through the oil-gas interface of the upper volume 37 with oil and space with gas in the housing 1 there is a constant movement of residues: up gas, down possible traces of water; and the collection and accumulation of oil in the upper volume. The movement of separation products between the volumes of sludge is carried out in the directions inherent in the natural process of separation in the field of gravitational forces, in contrast to the analogue and prototype, where the movement is made in the opposite directions to the natural. The duration of sludge between the discrete processes of product discharge is quite large, determined only by the ratio of the volume V _{CM of the} settled mixture and its flow rate Q _cm , in contrast to the analogue and prototype, where the selection process is constant and, thus, violates the natural sludge process. These circumstances are the key to the high efficiency of the separation process in the claimed invention. The level of accumulated sludge products is limited by setting the sizes and locations of siphons: 31 for oil extraction - size h _H , in the upper volume 37; 32 for the selection of the emulsion - size h _e in an average volume of 38; 33 for water extraction - size h _B , in the lower volume 39. Valve 27 maintains the pressure in the sump in a predetermined range of values by adjusting it to predetermined pressure drops in the sump and in the common reservoir 29: ΔP _min and ΔP _max . When the pressure in the sump is lower than the level providing ΔP _min , the valve 27 closes until the gas phase accumulates in the sump to the pressure creating ΔP _max , which ensures the functioning of the sump. Valve 27 will open. Closing and opening the valve 27 is carried out by moving its locking member in the interaction of the force from the differential pressure with the spring force without intermediate positions and stops, from one extreme position, fixed by magnetic force, to another and vice versa.

As the mixture accumulates in case 1, its level increases until the level of one of the liquid sludge products: oil, emulsion or water in the corresponding siphon 31 or 32 or 33 in its inlet branch reaches the top of one of the siphons 31, 32, 33 The drawing shows this moment when the oil level reached the top in the inlet branch of the siphon 31. The valve 27 is open and the gas phase through the gas line 14 and the discharge line 30 is discharged through the hydraulic lock 17 and then through the meter 26, which measures the volumetric flow rate of the gas phase, and the valve 27 into the common manifold 29. Oil overflows at a further rise in its level through the top of the siphon 31, fills the discharge line 30 to the top of the siphon 31, the siphon 31 begins to absorb oil, and a discrete cycle of oil extraction and discharge begins under the pressure of the gas phase from the middle and surface layers of its upper volume 37. This oil is the most settled, its state is not destroyed, with a vanishingly low content of water and gas residues. After overflowing, oil through the discharge line 30 fills the hydraulic lock 17, the gas line 14 to the level of the top of the siphon 31, blocks the gas phase flow and oil is discharged along the exhaust line 22, through the measuring section 23, then through the meter 26 and valve 27 into the common manifold 29. Counter 26 measures the amount of oil collected and discharged. The calculation unit BR 36 according to the readings of the sensors of the TLD and DNU 24, 25 calculate the hydrostatic weight of the oil column with a height of H ₀ - _{ΔР gst} and by the formula: ρ _H = _{ΔР gst} / H ₀ · g, where _{ΔR gst} - hydrostatic the weight of an oil column with a height of H ₀ ; ρ _H is the oil density; g is the acceleration of gravity; determine the density of the oil, thereby identifying the fluid flowing through the measured portion 23 as oil.

Like oil, density is also measured and emulsion and water are identified. Gas is identified by the lack of readings from the DNU and TLD sensors 24, 25.

When the oil level in the discharge line 30 drops to the exit of the siphon 31, the siphon 31 is broken and the discrete cycle of oil extraction and discharge ends. The overall level of the mixture in housing 1 has decreased. Residual oil in the discharge line 30, the hydraulic lock 17, the gas line 14, and the exhaust line 22 are discharged to the common reservoir 29 by the pressure of the gas phase. The gas phase through the released hydraulic lock 17 begins to be discharged into the common manifold 29. A cycle of accumulation, sludge and collection of its products has begun. The level of the liquid phase due to the supply of the mixture rises until the level of any of the liquid products: emulsion or water; in the input branch of the corresponding siphon 32 and 33 does not rise to the top of the siphon 32 and 33. A discrete cycle of selection and discharge of any liquid product begins. The selection of the emulsion is carried out from the near-surface most settled layer of the average volume 38, the selection of water is carried out from the lower most settled layer of the lower volume 39. The beginning and end of the cycle occurs in exact accordance, as is the case with oil. The beginning and end of the selection and discharge cycle of any separation product is also identified by sharp jumps and drops in the pressure of the gas phase and their magnitude. This is explained as follows: the meter 26 and the valve 27 are, among other things, local hydraulic resistances and when a new product enters them and exits them, a sharp change in the pressure of the gas phase in the sump occurs. The magnitude of the change depends on the density and viscosity of the products, which differ significantly in size. According to the testimony of the pressure sensor DD 15, the calculation unit BR 36 confidently identifies the product. According to the pressure of the gas phase and its temperature, measured by sensors DD and DT 15 and 16, the calculation unit BR 36, calculate the density of the gas phase and bring its parameters to normal conditions. Thus, they select and supply to the consumer separately and at the same time oil, emulsion, water and gas.

Using the invention in practice will effectively and efficiently separate the oil-gas mixture into its separation products, measure the density, flow rate of each product and submit it individually to the consumer, which will ensure their high-quality final commodity rectification.

Claims (2)

1. A method of separating a gas-water mixture from oil wells, comprising a constant supply of the mixture, its constant separation into liquid and gas phases, discharge of the latter to the consumer with simultaneous collection of liquid phase droplets in it and their disposal, constant separation of the mixture into water, gas, oil with an emulsion multiple sludge of a series of vertical mixture volumes replenished with emulsion, oil, gas from the upcoming volumes, from where water is removed down and gas upstream to the consumer, selection of settled oil with emulsion, regulation of Sheep oil with an emulsion, water, characterized in that the method consists of: a cycle of simultaneous accumulation, settling of the settled medium and collection of its products in the vertical settling according to the density and limited by the inter-productive surfaces of the three volumes section: oil and water-oil emulsion with the remains of water and gas, water with residues of oil and gas, the amount of residues is inversely proportional to the time of the sludge directly proportional to volume ratio mixture advocated its debit V _cm / Q _cm and a minimum of only limited solubility ost tkov in sludge products; a discrete cycle of selection and discharge to the consumer separately and at the same time of oil, emulsion, water and gas upon completion of their collection, separately and at the same time, of each liquid product in a predetermined quantity, and alternating the discharge of one of the liquid products with the discharge of gas, and vice versa, by locking with the liquid product gas flow or by releasing it at the end of the selection of a given amount of a liquid product, the product being identified by measuring the density of liquid products; measure the temperature of the gas phase and its pressure, the value of which is maintained within the specified limits, the volumetric flow rate of the separation products and limit the level of accumulated liquid products by dumping them to the consumer. 2. Four-product sump containing a vertical cylindrical body with inlet and outlet fittings, devices for selecting sludge products, a droplet eliminator, a drain pipe, level sensors, plates, characterized in that the droplet eliminator is made in the form of a hydrocyclone with a tangential inlet fitting, with a drain pipe limited bottom plates with straightening vanes, an outlet fitting communicated by a gas line equipped with pressure and temperature sensors, with a hydraulic lock, communicated, in turn, by an exhaust line equipped with a measuring section and hydrostatic sensors of the upper and lower levels, with a combined volumetric flow meter and further with a discrete bypass valve by magnetic locking of the extreme positions connected by the output to a common collector, as well as with a discharge line equipped with devices for oil extraction, emulsion, water, made in the form of siphons, and the siphons for emulsion and water are equipped with water locks, in addition, the sump includes a calculation unit associated with pressure sensors, temperature tours, and a combined level volume counter.

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