RU2315644C1 - Method of collecting and preparing oil - Google Patents

Abstract

FIELD: oil industry.

SUBSTANCE: method comprises supplying oil well product to the separator and tank of the stage of the preliminary water discharge, discharging liquids from the tank and heating, dehydrating and desalination of the liquids. The preliminary water discharge stage has several tanks connected in parallel.

EFFECT: enhanced efficiency.

4 dwg, 3 tbl

Description

The proposal relates to the oil industry, in particular to methods for the preparation of oil and can be used to separate emulsions.

There is a method of collecting and preparing oil well products according to the scheme (see Baykov N.M., Pozdnyshev T.N., Mansurov R.I. Collection and field preparation of oil, gas and water. M., Nedra, 1981, p. 81 - 83), which includes wells, an automatic metering unit, a reagent-demulsifier dosing unit, a first-stage separator, a settling apparatus (or tank) for preliminary oil dehydration, a crude oil pump, a heat exchanger, a crude oil heating unit (furnace), a deep dehydration unit oil, desalination unit (dehydrated fresh water mixer st, electric dehydrator), a separator of the 2nd (hot) separation stage, a tank for salable oil, a pump for pumping salable oil. This method provides for: additional supply of a reagent - demulsifier to receive a crude oil pump after its preliminary dehydration, return of hot drainage water from a deep dehydration unit to a crude oil line in front of the 1st stage separator, and hot desalinated water from an electric dehydrator to a previously dehydrated oil line after the heat exchanger in front of the deep oil dehydration unit. Hot oil after the desalination unit passes through the heat exchanger, heating the crude oil, and when it is cooled, it enters the commodity tank from which it is pumped to the consumer. The produced water that separated during the separation of the emulsion in the settling apparatus of the pre-dewatering stage enters the water treatment and treatment unit for its subsequent use in the reservoir pressure maintenance system. Petroleum gases separated in the 1st stage (high pressure gas) and the 2nd - hot - stage (low pressure gas) are sent to the gas processing plant.

One of the disadvantages of this method is the insufficiently high efficiency of emulsion separation of that part of crude oil, which is characterized by an increased concentration of mechanical impurities and stabilizers, since the measure of influence on any portion of crude oil, regardless of its physicochemical and rheological properties, is the same.

Closest to the technical solution to the present invention is a method for the joint collection, preparation of oil and processing, disposal of oily sludge (patent RU 2189846 B01D 17/04, publ. BI No. 27 of 09/27/2002), including the supply of products from wells to separators the first and second stages, the discharge of water from the preliminary water discharge tank, dehydration and desalination, the output of the intermediate layer from the preliminary water discharge tank, followed by heating it in a heat exchanger and performing its separation into oil, s and sludge in the phase separation unit, and before heating the intermediate layer in the heat exchanger, it is mixed in the mixer with an oil-containing sludge, which is fed to the mixer by an oil sludge collector, while the resulting mixture is heated in a heat exchanger at a temperature of 90-135 ° C, and The unit with the hydrocyclone effect created in it, coalescence and vacuum stripping of the hydrocarbon and solid parts of the mixture into which the heated mixture is introduced tangentially under Aviation 1.6-2.0 atmosphere.

One of the disadvantages of this method is the insufficient efficiency of the processes of deep dehydration and desalination of oil due to the presence in a sufficiently large amount of an intermediate layer in technological devices.

An object of the invention is to increase the volume of oil prepared for commercial condition by reducing the amount of the intermediate layer due to the separation of the raw materials into two streams - a low and high concentrated emulsion, and a more intense effect is produced on the highly concentrated emulsion (settling time, heating temperature, dosing volume of demulsifiers )

The technical problem is solved by the proposed method, including the supply of well products to the separator and the reservoir of the preliminary water discharge stage, the withdrawal of liquids from the preliminary water discharge tank with their subsequent heating, deep dehydration and desalination.

What is new is that the preliminary water discharge stage includes several tanks connected in parallel, each of which sequentially operates in one of the “fill-sludge-liquid removal” modes, and when liquid is removed, the upper layers of pre-dehydrated oil located above the level of the intermediate layer, after heating, they are sent to the devices of the desalination stage, and the lower layers with an intermediate layer after heating are sent to the devices of the stages of deep dehydration and desalination.

Figure 1 shows a schematic flow diagram.

Figure 2 shows the distribution of the concentration of chloride salts along the height of the sump 2 hours after filling.

Figure 3 shows the distribution of the concentration of chloride salts along the height of the sump 24 hours after filling.

Figure 4 shows data on the concentration of chloride salts in the upper 2/3 of the volume of the sump after 2, 15, 24 hours of static sedimentation after filling.

Schematic diagram illustrates the essence of the invention.

Coming to the preparation of the production of wells 1 (Figure 1) is sent to the end phase divider (KDF) 2 installation of oil treatment (UPN), where there is a separation and discharge of free formation water. Further, the raw material through the separator of the second stage 3 enters the tanks for preliminary discharge of water 4, each of which operates in the mode of sequential filling, sludge and liquid removal. From the reservoirs, the liquid, which is oil with a water volume fraction of not more than 1% (up to 2/3 of the total volume, stream I), is pumped 5 through the heat exchanger 6, furnace 7 and, after adding fresh washing water through the disperser 8, enters the desalination stage apparatus ( a dehydrator is possible) 9. Then, after cooling in the heat exchanger 6, the oil is sent through the hot stage separator 10 to the buffer tank 11. The rest of the feed from the tanks 4 with an intermediate layer (up to 1/3 of the total volume, stream II) is treated with a reagent-d dispenser 13 the emulsifier and pump 5A through the heat exchanger 6A, furnace 7A, is sent to the sumps of the dewatering stage 14 and then after adding fresh washing water through the disperser 8A to the desalination stage apparatus (an electric dehydrator is possible) 9A. Further, the oil for cooling passes through the heat exchanger 6A, the hot stage separator 10 and enters the buffer tank 11. From the buffer tank 11, marketable oil, which is a mixture of oil flows I and II, is pumped by an external pump 12 to the main oil pipeline system (in FIG. shown).

The entire intermediate layer formed in the apparatus of the stages of preliminary dehydration and desalination is collected in the sump of the dehydration stage 14.

The produced water that separates in KDF 2 and in the preliminary water discharge tanks 4 is sent to the treatment plant tank (OC ₁ ) 15. Drainage from the sump of the dewatering stage 14 is sent to the intermediate layer separation tank (OS ₂ ) 16. Drainage from the sumps of the desalination stage 9, 9A by pump 17 and the film oil from the tank of the treatment plant 15 by pump 18 is pumped into the fluid flow entering the inlet of pump 5A (stream II). The intermediate layer from the reservoir 16 is directed by the pump 19 to the processing unit of the intermediate layers.

The gas separated in the separator of the second stage 3 is sent directly to the gas line. The gas released in tanks 4, 11, 15, 16 is collected through a light fraction capture system (SF) and supplied to a compressor station (CS), from where it is sent through a gas line for processing.

Wastewater after treatment in tanks 15 and 16 is sent to the PPD system.

To solve the technical problem, the incoming raw materials are divided according to the degree of the necessary impact for the production of marketable oil. At the same time, a part of the raw material is released, due to a more intense effect on which the rate of accumulation of the intermediate layer in the apparatus of the deep dehydration and desalination stages of oil decreases, which leads to a decrease in its volume.

Concrete example

The experiments with raw materials entering the input of the oil treatment facilities, allowed us to assess the possibility of using the proposed method. The essence of the experiments was as follows. At UPN, incoming raw materials were selected. After static sedimentation for a predetermined time of 2, 15, 24 hours, the liquid was divided into 6 samples according to the height of the sump, each of which was evaluated by the values of the parameters that determine the quality of the prepared oil, namely, the volume fraction of emulsified water and the concentration of chloride salts . In addition, the concentration of iron sulfide and density were measured in the samples, and disperse analysis was performed. Table 1 shows the measurement data of the parameters of raw materials, and table 2 shows the calculation of the rate of deposition of droplets according to the Stokes formula.

As follows from the data given in table 2, with a relatively low volume fraction of emulsified water, the potential for its removal under the influence of Stokes forces for specific objects is not the same, which is determined by the combination of properties of the emulsion: viscosity of oil, density of water and oil, diameter of droplets of emulsified water. This difference was clearly manifested with a short settling time (2 hours), while prolonged exposure to static conditions (24 hours) led to the concentration of drops of emulsified water in the lower, bottom layers in all samples (Figs. 2, 3). In this case, the concentration of chloride salts in oil, which constitutes the upper 2/3 of the volume of sedimentation tanks, after 24-hour sedimentation, ranged from 92 to 333 mg / dm ³ , which gives grounds to evaluate it as sufficiently well prepared for desalination (Figure 4). The lowest concentration of chloride salts was with low oil viscosity, high salinity of emulsified water and a small proportion of small drops in its composition (Bavly, Devon, see Tables 1, 2), and the highest in the sample, in which the proportion of small drops in the composition emulsified water was high ("Aktash, Devon", see table 1, 2). For Nurlat, Carbon oil (see Table 2), the considered oil preparation option is difficult to implement due to its high viscosity.

Next, we determined the conditions under which it is possible to bring to the required quality of oil (GOST R 51858-2002, group 1), which is the upper 2/3 (levels 3-6 in the height of the sump) and lower 1/3 of the volume (respectively, the levels are 1- 2) after prolonged static settling. For this, experiments were carried out on deep dehydration and desalination of oil after 15 and 24 hours of static sedimentation. The conditions and experimental results are presented in table 3. From the data in table 3 it is seen that the concentration of chloride salts in the volume of oil extracted after static sedimentation for 15 and 24 hours, up to 2/3 of the total treated volume, can be reduced to less than 100 mg / dm ^{3 by a} single treatment with fresh wash water (desalination stage) with a mass fraction of water less than 0.5%. Accordingly, an increase in the settling time of the lower 1/3 of the emulsion volume, in which drops of emulsified water were concentrated during static sedimentation, led to an increase in the depth of its dehydration.

Thus, the application of the proposed method allows to divide pre-dehydrated oil into volumes that are characterized by a low and predominantly high concentration of emulsified water and carry out a more intense effect on the volume, which is a highly concentrated emulsion, as a result of which the rate of accumulation is slowed down and, consequently, the number of intermediate layers.

The technical and economic efficiency of the proposed method consists of an increase in the volume of oil prepared to commodity condition and a decrease in the amount of the intermediate layer by 10% or more. The use of the combined technology of oil preparation and the use of high-performance low-temperature demulsifying reagents can significantly complete the processes of mass transfer and coalescence of droplets before raw materials arrive at the oil treatment unit. With a high degree of destruction of the raw material, it can be divided into qualitatively different volumes, of which the larger will be represented by a low concentration, the smaller by a highly concentrated emulsion. This separation is possible after prolonged static sedimentation of the raw materials, which can be carried out in tanks for preliminary discharge of water. The mode of static sedimentation, which allows to minimize the ascending flows in these tanks, leads to the transition of a significant part of the drops of emulsified water into the lower, bottom layers. At the same time, only a small number of drops remain in the upper layers, the removal of which does not require the preparation of oil in a full cycle. This makes it possible to increase the settling time and, if necessary, heat to a higher temperature that part of the raw material that is a highly concentrated emulsion, as a result of which conditions are created to increase the efficiency of its separation and reduce the amount of the intermediate layer, which requires autonomous preparation on the processing unit for the intermediate layers.

Table 3 - Indicators of dehydration and desalination of oil and emulsion Sample number Characteristics of the processed oil, emulsion Volume fraction of water,% The concentration of chloride salts, mg / DM ³ Demulsifier dosage, g / t The dosage of fresh wash water,% Settling time, h The volume of separated water, cm ³ after settling Residual mass fraction of water,% The concentration of chloride salts, mg / DM ³ SNPCH 4460 to oil Reef in the water at a temperature of 50 ° C without heating at 50 ° C without heating one 2 3 four 5 6 7 8 9 10 eleven 12 13 one “Kuakbash, carbon”, after 15 hours of sedimentation, 2/3 of the volume (top) 1,50 394 twenty 5 four fifteen 5 5 0.24 86 2 “Kuakbash, carbon”, after 15 hours of sedimentation, 2/3 of the volume (top) 0.95 278 - - - four fifteen 0 cl 0.18 92 3 - - 5 four - four - 0.24 97 four - twenty 5 four - 5 - 0.44 64 5 “Kuakbash carbon”, a mixture of samples after 15 hours of sedimentation and 24 hours of sedimentation, 1/3 of the volume (bottom) 5.20 - - - four - 6 - 0.84 349 6 - - - 8 - 6 - 0.62 292 7 thirty - - 8 - 7 - 0.46 218 8 "Aktash, Devon", after 24 hours of sedimentation, 2/3 of the volume (top) 0.24 333 - twenty 5 four fifteen 5 6 0.24 98

Continuation of table 3 one 2 3 four 5 6 7 8 9 10 eleven 12 13 9 "Aktash, Devon", a mixture of samples after 15 hours of sedimentation and 24 hours of sedimentation, 1/3 of the volume (bottom) 0.84 890 - - - four - 0 cl 0.32 464 10 - - - 8 - cl - 0.20 280 eleven twenty - - four - 0 - 0.18 278 12 twenty - - 8 - cl - 0.14 220 13 “Bavly, Devon”, after 15 hours of standing, 2/3 of the volume (top) 0.12 154 - - 5 four - 5 - 0.24 72 fourteen - twenty 5 four - four - 0.20 63 fifteen “Bavly, Devon”, a mixture of samples after 15 hours of sedimentation and 24 hours of sedimentation, 1/3 of the volume (bottom) 0.72 778 - - - four - cl - 0.14 298 16 - - - 8 - cl - cl 108 17 - - twenty 8 - cl - cl 102 eighteen “Bavl, carbon”, after 24 hours of sedimentation, 2/3 of the volume (top) 0.14 186 - - 5 four - 5 - 0.32 84 19 - twenty 5 four - four - 0.60 72 twenty - twenty 5 four fifteen 5 5 0.18 fifty 21 "Bavl, carbon", a mixture of samples after 15 hours of sedimentation and 24 hours of sedimentation, 1/3 of the volume (bottom) 6.20 7280 - - - four - 6 - 0.72 744 22 - - - 8 - 6 - 0.30 380 23 twenty - - four - 6 - 0.68 698 24 twenty - - 8 - 6 - 0.28 320 25 - - 5 8 - 10 eleven 0.32 220

Claims (1)

A method for collecting and preparing oil, including supplying well products to a separator and a tank of a preliminary water discharge stage, withdrawing liquids from a preliminary water discharge tank with their subsequent heating, deep dehydration and desalination, characterized in that the preliminary water discharge stage includes several tanks connected in parallel, each of which sequentially operates in one of the modes "filling-sludge-liquid removal", and when removing liquid, the upper layers are preliminarily dehydrated oil located above the level of the intermediate layer is sent after heating to the desalination stage apparatuses, and the lower layers with the intermediate layer after heating to the apparatuses of deep dehydration and desalination stages.

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