RU2291960C1 - Method for collecting and preparing drainage water - Google Patents

Abstract

FIELD: oil industry, possible use for preparing oil emulsion at oil preparation plants.

SUBSTANCE: method includes feeding oil emulsion received from oil fields into devices for preliminary water disposal, separating water part from oil emulsion in preliminary water disposal devices and draining of water part to cleaning structures, cold separation of gas from oil emulsion in buffer vessels, heating of oil emulsion in heat exchangers and in furnace, hot dehydration of oil emulsion at hot sediment stages, desalination of oil emulsion in electric dehydrators with feeding of fresh water into electric dehydrators through disperser, feeding of drainage water after hot sediment and electric dehydrators to beginning of process at devices for preliminary water disposal, feeding of processed oil from electric dehydrators through heat exchangers into buffer vessels for processed oil, hot separation of gas in buffer vessels for processed oil and feeding of oil to consumer. In accordance to invention devices for preliminary oil disposal are divided on two steps. First step is operated in normal mode with feeding of oil emulsion from oil fields into inlet and from preliminary water disposal devices into buffer vessels. Second step is bound in parallel to first step, feeding of oil emulsion from oil fields into inlet of second step of preliminary water disposal devices is prevented. Drainage water after hot sediment and electric dehydrators is fed to inlet of second step of preliminary water disposal devices, without mixing thereof with water-oil emulsion received from fields. From second step of preliminary water disposal devices part of water is fed into cleaning structures and oil emulsion is fed into inlet of buffer vessels. Influx of drainage water into inlet of second step of preliminary water disposal devices is performed through lower manifold-distributor of device below layer of water cushion, while technological process in second step of preliminary water disposal devices is performed at temperature of 50-80°C.

EFFECT: increased efficiency of separation of water-oil emulsion at preliminary dehydration stage onto oil and water, stabilization of hot dehydration stages operation, desalination of oil and prevention of growth of number of intermediate layers from stable emulsions.

1 ex

Description

The invention relates to the oil industry and may find application in the preparation of oil emulsions in oil treatment plants.

A known method of dehydration and desalination of an oil emulsion of an intermediate oil layer formed in the tanks and sludge apparatuses of oil treatment plants, comprising supplying an oil emulsion to the tank at a rate of 0.5-1 m ³ / h through a layer of wastewater of the same oil pool with mineralization less than the limit saturation with a temperature of 20-30 ° C and a thickness of the wastewater layer 6-8 m, oil separation and direction to the input of the oil treatment unit (RF Patent No. 2256791, class E 21 B 43/34, publ. 2005.07.20).

The known method allows you to quite effectively separate the oil-water emulsion into oil and water and separate the mechanical impurities. However, the resulting drainage water does not meet the requirements for water for the reservoir pressure maintenance system.

Closest to the proposed invention in technical essence is a method of collecting and preparing drainage water, comprising supplying an oil emulsion coming from oil fields to serially connected water pre-discharge apparatuses, separating part of the water from the oil emulsion in series-connected water pre-discharge apparatuses and discharging part of the water to wastewater treatment plants, cold gas separation from oil emulsions in buffer tanks, heating oil emulsions in heat exchangers and in a furnace, hot dehydration of the oil emulsion at the stages of hot sludge, desalination of the oil emulsion in electric dehydrators with fresh water supplied to the electric dehydrators, supply of drainage water after hot sludge and electric dehydrators at the beginning of the process to the preliminary water discharge devices, supply of finished oil from the dehydrators to the buffer tanks oil, hot gas separation in the buffer tanks of the finished oil and pumping oil to the consumer (V.P. Tronov "Oil gathering systems and hydrodynamics of the main technological processes." Feng. Kazan, 2002, p.335-337 - prototype).

The disadvantage is that the mixing of drainage water containing a significant amount of oil products (up to 30-40%) and mechanical impurities (iron sulfide, etc., up to 2000 mg / dm ³ ), with commercial oil emulsion leads to its rapid contamination with mechanical impurities and stabilization of the emulsion. Demulsification becomes impossible even with a significant increase in temperature and concentration of demulsifier. This causes a sharp decrease in the efficiency of the dehydration process and can lead to disruption of the operating mode of the oil treatment unit.

The invention solves the problem of increasing the efficiency of the separation of oil-water emulsions at the stages of preliminary dehydration into oil and water, stabilizing the operation of the stages of hot dehydration, desalting of oil and preventing the increase in the number of intermediate layers consisting of persistent emulsions.

The problem is solved in that in a method for collecting and preparing drainage water, including supplying oil emulsion from oil fields to water pre-discharge apparatuses, separating part of the water from oil emulsion in water pre-discharge apparatuses and discharging part of the water to treatment facilities, cold gas separation from an oil emulsion in buffer tanks, heating the oil emulsion in heat exchangers and in a furnace, hot dehydration of the oil emulsion at the stages of hot sludge, desalination of the oil emulsion into an electric dehydrator tori with the supply to the electric dehydrators through the fresh water disperser, the supply of drainage water after hot sludge and the electric dehydrators at the beginning of the process to the preliminary water discharge devices, the supply of finished oil from the electric dehydrators through heat exchangers to the buffer tanks of the finished oil, hot gas separation in the buffer tanks of the finished oil and pumping oil consumer, according to the invention, the preliminary water discharge devices are divided into two stages, the first stage is operated in normal mode with the supply of oil emulsion and from the fields to their entrance and from the preliminary water discharge devices to the buffer tanks, the second stage is tied in parallel with the first stage, the oil emulsion from the fields is excluded, the second stage of the preliminary water discharge devices is inlet, the drainage water after hot sludge and electric dehydrators are fed to the entrance of the second stage of the preliminary water discharge apparatus, without mixing with the oil-water emulsion coming from the fields, from the second stage of the preliminary water discharge apparatus discharge frequently water to treatment plants and the supply of oil emulsion to the entrance of the buffer tanks, while the input of drainage water to the inlet of the second stage of the apparatus for preliminary water discharge is carried out through the lower mother liquor-distributor of the device under the layer of the water cushion, and the technological process in the second stage of the apparatus for preliminary water discharge temperature 50-80 ° С.

SUMMARY OF THE INVENTION

In almost all oil treatment plants, drained water from the stages of hot dehydration and desalination due to the significant content of oil products (up to 30-40%) is treated repeatedly, returning it to the stream of oil emulsion coming from oil fields. At the same time, mixing a commercial emulsion with drainage water containing mechanical impurities (iron sulfide, etc., up to 2000 mg / dm ³ ) often leads to stabilization of the oil emulsion, an increase in the thickness of the intermediate layer, a decrease in the rate of its destruction and, at a certain thickness, complete suppression of the process of transition of globules of the dispersed phase into the water layer in the settling apparatus. This, in turn, leads to a decrease in the efficiency of the process of preliminary dehydration of well products, return with the oil phase and the accumulation of mechanical impurities at the stages of hot dehydration and desalination. Thus, the thickness of the intermediate layers in the apparatus for hot dehydration and desalination increases and the risk of disrupting the technological mode of operation of oil treatment plants increases.

The proposed invention solves the problem of increasing the efficiency of separation of oil emulsions at the stages of preliminary dehydration into oil and water, stabilizing the operation of the stages of hot dehydration, desalting of oil, separation of mechanical impurities and preventing the growth of the number of intermediate layers consisting of persistent emulsions.

To solve this problem, the discharge of drains from the stages of hot dehydration and desalination is carried out in a separate settling apparatus, without mixing with the oil-water emulsion coming from the fields. The effectiveness of the proposed method for the preparation of drainage water is also achieved by maintaining a high temperature of the process (50-80 ° C). For more effective cleaning of the drainage from mechanical impurities, the drainage water is introduced into the apparatus through the lower mother liquor distributor under the layer of the water cushion. The capacity of the device is selected based on the volume of discharged drains and the results of laboratory tests. Oil from the apparatus is sent to the buffer capacity of the feed pump, water with a high content of mechanical impurities is drained to the treatment plant. As a result, it is possible to increase the efficiency of the preliminary dehydration stage, to stabilize the operation of the hot dehydration and desalination stages by removing up to 90% of mechanical impurities from the oil preparation process. Thus, in the apparatus of oil treatment plants, the possibility of an increase in the number of intermediate layers, which upon accumulation lead to disruptions of the technological regime, is excluded. The preparation of drainage water and the separation of mechanical impurities during passage through the water cushion at a higher temperature than in the apparatus of the preliminary dehydration stage and without mixing with the raw materials coming from the oil fields is much more effective. The proposed method, if necessary, allows the treatment of drainage water with other chemicals separately from the total flow of raw materials.

The technological process is shown in the drawing.

Water pre-discharge devices are divided into two stages. The oil emulsion from the oil fields is sent to the first stage water pre-discharge apparatus 1. Separated water from the first stage 1 water pre-discharge apparatus with oil content up to 500 mg / dm ^{3 is} fed for treatment to treatment facilities. The water content of the oil emulsion after the apparatus for preliminary discharge of water 1 is stable and amounts to 5%. After the apparatus for preliminary water discharge 1, the oil emulsion is sent to buffer tanks 2, where the gas is cold separated and from where the oil emulsion is pumped through the heat exchangers 4 with the raw material pump 3, where it is heated by the finished oil leaving the unit to 25-35 ° С and sent to the furnace 5 After the furnace 5, the oil emulsion heated to a temperature of 50-80 ° C passes through two stages of hot sludge 6 and 7 and is supplied for desalination to electric dehydrators 8. For better desalination, up to 5% waist water. Drainage water after stages of hot sludge 6 and 7 and electric dehydrators 8 with an oil content of up to 30-40% and mechanical impurities up to 2000 mg / dm ^{3 are} sent to the preliminary water discharge apparatus of the second stage 9, without mixing with the oil-water emulsion from the fields. The input of drainage water to the inlet of the second stage of 9 devices of preliminary water discharge is carried out through the lower mother liquor-distributor of the device under the layer of the water cushion, and the technological process in the last stage of the preliminary water discharge devices is carried out at a temperature of 50-80 ° С. Oil from the apparatus 9 is sent to the buffer tank 2 of the feed pump 3, and water with a high content of mechanical impurities is diverted to treatment facilities. From the electric dehydrators 8, the finished oil is fed through the heat exchanger 4 to the buffer tanks of the finished oil 10, where hot gas separation is performed. Pumping oil to the consumer by pump 11.

The increase in the efficiency of the preliminary dehydration stage, as well as the stabilization of the stages of hot dehydration and desalination in the described method is achieved by eliminating the mixing of drainage water with raw materials from oil fields, the effectiveness of the preparation of drainage water is achieved by maintaining a high temperature of the process.

Concrete example

At the Kuakbash installation of sour oil treatment (KUPVN) NGDU Leninogorskneft failed to prepare oil to the 1st quality group. The installation of preliminary dehydration (OPS) at the CCLM did not provide a clear oil-water interface. As a result, the automatic drainage valves of the phase separation detectors did not work and the operators had to switch to manual regulation of the operation of the settlers depending on the pressure on the installation. This mode of operation led to the fact that, together with water, a significant amount of oil (up to 8%) was discharged into the sewage treatment apparatus, impairing the quality of the wastewater prepared for the reservoir pressure maintenance system. The process of oil preparation was destabilized due to the ingress of a highly watered emulsion at the stage of hot dehydration.

At KUPVN, the discharge of drains from the stages of hot dehydration and desalination was sent to a separate settling apparatus (UPS-3), where mixing with water-oil emulsion coming from the fields was excluded. The effectiveness of the preparation of drainage water is achieved by maintaining a high temperature of the process (50-80 ° C), by eliminating mixing with raw materials from oil fields. For more effective cleaning of the drainage from mechanical impurities, the drainage water is introduced into the apparatus through the lower mother liquor distributor under the layer of the water cushion. The capacity of the device is selected based on the volume of discharged drains and the results of laboratory tests. Oil from the apparatus is sent to the buffer capacity of the feed pump, water with a high content of mechanical impurities is drained to the treatment plant.

As a result of applying this method, it was possible to increase the efficiency of the preliminary dehydration stage, to stabilize the operation of the hot dehydration and desalination stages by removing up to 90% of mechanical impurities from the oil preparation process. Thus, with the use of this method on the CCLM in settling apparatus, the increase in the number of intermediate layers consisting of persistent emulsions stopped. The preparation of drainage water and the separation of solids while passing through the water cushion at a higher temperature than in the apparatus of the pre-dewatering stage and without mixing with the raw materials coming from the oil fields is much more efficient. The proposed method, if necessary, allows the treatment of drainage water with other chemicals separately from the total flow of raw materials.

After the successful implementation of the proposed method for collecting and preparing drainage water from the stages of hot dehydration and desalination, the unit was operated without technological breakdowns and a stable delivery of finished oil was achieved in the 1st quality group. The need for an overdose of the demulsifier disappeared, the consumption of the demulsifier decreased by 15%. The annual economic effect of saving chemicals alone amounted to about 2.5 million rubles.

Application of the proposed method will improve the efficiency of separation of oil emulsions at the stages of preliminary dehydration into oil and water, stabilize the operation of the stages of hot dehydration and desalination of oil, separate mechanical impurities and prevent the growth of the number of intermediate layers consisting of persistent emulsions.

Claims (1)

A method for collecting and preparing drainage water, including supplying an oil emulsion from oil fields to water pre-discharge apparatuses, separating part of the water from the oil emulsion in preliminary water discharging apparatuses and discharging part of the water to treatment facilities, cold gas separation from the oil emulsion in buffer tanks , heating the oil emulsion in heat exchangers and in the furnace, hot dehydration of the oil emulsion at the stages of hot sludge, desalination of the oil emulsion in electric dehydrators with feeding to the electrode hydrators through a fresh water disperser, the supply of drainage water after hot sludge and electric dehydrators to the beginning of the process to the preliminary water discharge devices, the supply of finished oil from the dehydrators through heat exchangers to the finished oil buffer tanks, hot gas separation in the finished oil buffer tanks and pumping oil to the consumer, which differs the fact that the preliminary water discharge devices are divided into two stages, the first stage is operated in the normal mode with the supply of oil emulsion from the fields to their entrance and from water pre-discharge apparatuses to buffer tanks, the second stage is tied in parallel to the first stage, the oil emulsion flowing from the fields is excluded from the input to the second stage of water pre-discharge apparatuses, drainage water after hot sludge and electric dehydrators are fed to the input of the second stage of water pre-discharge apparatuses without mixing with the oil-water emulsion coming from the fields, from the second stage of the preliminary water discharge apparatus, part of the water is discharged to the treatment facilities I and the supply of oil emulsion to the entrance of the buffer tanks, while the input of drainage water to the inlet of the second stage of the apparatus for preliminary water discharge is carried out through the lower mother liquor-distributor of the device under the layer of the water cushion, and the technological process in the second stage of the apparatus for preliminary water discharge is carried out at a temperature of 50- 80 ° C.