RU2014283C1 - Method for production of hot water from highly saline waters - Google Patents

Abstract

FIELD: oil producing industry. SUBSTANCE: water flower, supplied to preliminary and final heating in recovery heaters, is produced by mixing in a certain proportion a portion of deaerated water and a portion of demineralized water produced in a thermal water demineralization plant (TWDP). The TWDP concentrate is supplied for heating the source highly saline water. Steam produced in a steam generator is used as heating steam in the water recovery heaters, in the TWDP, and in steam generator deaerator. The source highly saline water, which is fed in the TWDP, is softened by a sodium-cation process. Demineralized water, produced in the TWDP and used for feeding the steam generator, is directed to the additional deaeration. EFFECT: increased efficiency of the process. 3 cl, 1 dwg

Description

 The invention relates to water treatment, in particular to the preparation of hot water from highly saline waters for thermal treatment of an oil reservoir to enhance oil recovery.

A method of producing hot water from sea water for injection into the oil reservoir, comprising heating it in evaporators with external boiling zone ^to 100 ° C with preventing scale formation via chalky "primer" (1).

 The disadvantages of the method are its instability due to contact heating of water and increase its corrosion activity.

Another known method of softening water to be used for heating the saline water before injection into the oil reservoir to increase oil recovery comprising heating the untreated water to a temperature of 25-40 ^{° C,} mixing with lime precipitation bicarbonate, separating the precipitate, magnetic treatment, heating and separation into two streams, one of which is subjected to sodium cationization, deaeration and evaporation, mixing the resulting steam with another stream of water and wastewater of sodium cationite filters, thermal softening with separation from the sediment softening water and gas separation, replenishment of a steam generator generating steam with a pressure of 0.2-0.3 MPa higher than the saturation pressure in the heat softener, blowing the steam generator and regeneration of sodium-cation exchange filters by it, after pre-cooling in the expander and heat exchanger, the supply of heated thermally softened water into the well (2).

The disadvantages of this method are: although the power of the steam generator and glubokoumyagchennoy but highly mineralized water, unreliable operation termoumyagchitelya connected with the violation of the two-phase flow hydrodynamics and form insoluble deposits on the walls termoumyagchitelya, constructive complexity termoumyagchitelya at higher water temperatures above 180 ^{° C} and a pressure of more than 0.6 MPa

 Closest to the proposed method is the preparation of feed water from highly saline water, including mechanical clarification of the source water from suspended particles, ion treatment, regenerative heating of water, evaporation to form steam and concentrate with purge water, supply of a concentrate of salts of purge water for the regeneration of ion exchanger and steam - into the oil reservoir (3).

 The disadvantage of this method is the relatively high cost of the process and low reliability.

 A comparative analysis of the proposed technical solution with the prototype made it possible to establish compliance with the first criterion of "novelty."

 The study of other technical solutions showed that the proposed method meets the criterion of "significant differences".

 The purpose of the invention is to increase reliability and reduce the cost of the process.

 The drawing shows a diagram of the preparation of hot water from highly saline water to implement the proposed method.

 The method is as follows.

The feed water heated in the water-water 1 2 and 3, the steam regenerative heaters to a temperature of 30-35 ^{° C} and purified from mechanical admixtures and organic contaminants on the pretreatment and 4 deep softening the primary demineralizer 5. Glubokoumyagchennuyu water steam 6 heated in the recuperative heaters 7 and 8 to the temperature required for deaeration of the water, and served in the deaerator 9. The flow of deaerated water 10 after pumping by the pump 11 is divided into two parts in a ratio of 1: 0.05-11. The first part 12 is sent for demineralization (desalination) to a multi-case desalination plant 13. Demineralized water is supplied by stream 14 to an additional deaerator 15 of the steam generator circuit 16. The excess demineralized water (part 17) is mixed with the second part 18 of softened water in mixer 19 and using pump 20 mixed stream is pumped sequentially through Steam recuperative heaters 21 and 22, in which it is heated to a temperature of 100-275 ^{° C} and injected into the formation (stream 23).

For heating the water, the steam obtained in the steam generator 16 is used. Demineralized water from the deaerator 15 is supplied to the steam generator 16 using the pump 24, and the resulting sharp steam 25 with a pressure of up to 2 MPa is supplied in three streams to the heater 22, to the steam jet compressor 33 and to the throttle device 26, mix the last two streams with the formation of a stream 27 of reduced steam with a pressure reduced to 0.6 MPa, which is supplied to the deaerator 15, heaters 21 and 8 and desalination plant 13. The condensate heating steam from heating Ateliers 8.21 and 22 and from the thermal desalination plant 13 are discharged by stream 28 into the deaerator. Secondary steam from the last stage of the desalination plant with a pressure above atmospheric is divided into three streams. The first two (stream 30) are fed to the heaters 3 and 7 and to the deaerator 9, the condensate 32 from these devices is discharged to the mixer 19, and the third stream 31 is compressed in the compressor 33 to the pressure of the reduced steam stream with hot steam from the steam generator. Concentrate 34 termoopresnitelnoy installation is passed through preheater 2, in which its temperature is reduced to 30-40 ^{° C} and fed to the regeneration demineralizer filter 5, and 35 waste liquors discharged into drainage.

 Example of the method with optimal parameters.

The plant for the preparation of 150 t / h of hot water with a temperature of 200 ^{° C} using water of highly Plast following composition, meq / kg: Na ⁺ = = 361; Ca ²⁺ = 47; Mg ²⁺ = 23; Cl ^- = 423; SO ₄ ^2- = 0.7; HCO ₃ ^- = 8.3. Total salinity 19 g / kg. initial temperature 10 ^o C.

The initial water flow rate 202 ton / hr preheated to a temperature of 30-35 ^{° C} to increase the water treatment processes, but no more, because of the danger of scale on the heat transfer surface of the heater. At pretreatment clarified water, adding a coagulant, the clarified water is subjected to deep softening sodium cation unit (to a residual hardness of 0.05 meq / l), then heated to a temperature of 95-98 ^{° C} and a flow rate of 168 ton / h is fed into the deaerator. The deaerator atmospheric type glubokoumyagchennuyu water heated to 104 ^{° C} and deaerated. Then the stream is divided in a ratio of 1: 1.2. A part of the deaerated water stream with a flow rate of 76.3 t / h is fed to a five-stage “instant” boiling unit, and the remaining stream of deep-softened deaerated water is mixed with demineralized water obtained from the desalination plant and 57.6 t / h condensate from heat exchangers. The mixed flow with a total salinity of 11-12 g / kg and a flow rate of 150 ton / hr preheated to a temperature of 147 ^{° C} reduced steam with a temperature of 160 ^{° C,} then - to a temperature of 200 ^{° C} with steaming temperature of 208 ^{° C} and pumped into the well. Glubokoumyagchennoy for heating water to the temperature required for its deaeration is fed up to 9 t / h of steam with a reduced temperature of 160 ^{° C,} 0.07 ton / hr of this steam is fed to the deaeration of the water circuit of the steam generator and 29 t / h - on termoopresnitelnuyu installation. The total steam consumption is 70.6 t / h. One stripped off solution of “soft” salts with a concentration of sodium ions up to 110 g / kg in an amount of 17 t / h is fed to chemical water filters for the regeneration of cation exchange resin. The spent solution is discharged into the drainage.

EXAMPLES of the implementation of the method with extreme values of the parameters:
for highly saline water of the following composition, mEq / l:
Na ⁺ = 170; Ca ²⁺ = 53; Mg ²⁺ = 27; Cl ^- = 241; SO ₄ ^2- = 0.5; HCO ₃ ^- = 8.5 and a total salinity of 10 g / kg, the flow rate of the source water is 200 t / h. After pretreatment, similarly to the previous example, a deaerated water stream having a total flow rate of 168.5 t / h. divided into two streams in a ratio of 1: 0.05. The first stream with a flow rate of 159.3 t / h is fed to a desalination plant, and the remaining stream of deeply softened deaerated water is mixed with demineralized water and condensate. The mixed stream at a rate of 150 t / h total mineralization 0.6-0.8 g / kg is heated sequentially by first steaming pressure up to 0.6 MPa, and then steamed to a temperature of 200 ^{° C} and pumped into the well. The total steam consumption is 70.6 t / h. The flow rate of purge water of a desalination plant used as a regeneration solution in chemical water treatment is 16 t / h with a concentration of 110 g / kg.

For highly mineralized water composition, mEq / L: Na ⁺ = 680; Ca ²⁺ = 13; Mg ²⁺ = = 7; Cl ^- = 690; SO ₄ ^2- = 2.8; HCO ₃ ^- = 7.2, and with a total salinity of 30 g / kg, the flow rate of the source water is 185.3 t / h. After heating, filtering, softening and deaeration. a stream with a flow rate of 156 t / h is divided into two parts in a ratio of 1:11. The first stream with a flow rate of 13.2 t / h is fed to a desalination plant, and the remaining stream of deeply softened deaerated water is mixed with desalinated water. The mixed stream at a rate of 150 t / h and total mineralization 28-29 g / kg is heated successively throttled to 0.6 MPa, and then steamed to a temperature of 200 ^{° C} and pumped into the well. The total steam consumption is 70.6 t / h. The flow rate of purge water of a desalination plant used as a regeneration solution in chemical water treatment is 3.69 t / h with a concentration of 110 g / kg.

The invention allows to obtain hot water having a temperature of 100-275 ^{° C} with salt content of saline water to 30 g / kg.

 The economical operation of the chemical water treatment unit is ensured by the fact that for the regeneration of cation exchange resin a purge desalination plant is used and the cost of imported salt is not required.

 The required water softening depth (to a residual hardness of 0.05 mEq / kg) is due to stepwise countercurrent sodium cationization with a six-fold excess of the regeneration solution.

 The performance of the thermal desalination plant is determined by the need for the chemical water treatment unit in the regeneration solution (concentrate), which will depend on the relative hardness of the saline water, i.e. from the ratio of the concentration of calcium and magnesium ions to the concentration of sodium ions.

 Part of the desalinated water produced by the desalination plant is used to feed the steam generator, thereby ensuring a non-scale mode of operation.

 Mixing excess demineralized (desalinated) water with deeply softened water can reduce the overall salinity of the water.

 Sequential heating in recuperative steam-water heaters, first reduced to 0.6 MPa, and then with hot steam, reduces capital costs, because preheating with reduced steam parameters reduces the metal consumption of heaters.

 Throttling of steam to a pressure of 0.6 MPa is due to the fact that at this pressure the reduced costs for desalination are minimal.

 The vapor pressure of the last stage of the desalination plant is set above atmospheric and the heat of this steam is used to heat the source water in order to prevent heat loss to the environment and eliminate the need for vacuum devices of the desalination plant.

Claims (3)

1. METHOD FOR PRODUCING HOT WATER FROM HIGH-MINERALIZED WATERS, including preliminary and main purification of the source water on the filters, supplying it to desalination with the formation of secondary steam, concentrate directed to the regeneration of the filters, and demineralized water sent to feed the steam generator to produce hot steam in that, in order to increase reliability and reduce the cost of the process, the raw water is preheated to 30 ° ^C, and before its desalination warmed to deaeration temperature and direction they are sent for thermal deaeration, the secondary steam is directed in three streams respectively to heat the source water, its thermal deaeration and for compression into a steam-jet compressor due to the energy of sharp steam, the sharp steam is divided into three streams, the first of which is reduced to a pressure of 0.6 MPa, and the second is fed to the steam-jet compressor, mixed with the first to obtain a reduced steam stream and fed to the water desalination process, a portion is removed from the deaerated water stream, respectively, in a ratio of 1: 0.05 - 11 and mixed with pre part of the demineralized water, the mixed stream is fed for preliminary and final heating to recuperative heat exchangers, and the concentrate is fed to the feed water, while two parts are diverted from the reduced steam stream, one of which is sent to heat the water to the deaeration temperature, and the other part the third stream of hot steam is directed respectively to the preliminary and final heating of the mixed stream.  2. The method according to claim 1, characterized in that when the water is purified, sodium cation exchange softening is carried out.  3. The method according to claims 1 and 2, characterized in that before the steam generator, demineralized water is sent for additional deaeration.

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