CN102838977B

CN102838977B - Method of preparing polyacrylamide solution for recycling oilfield produced water including Ca<2+> and Mg<2+>

Info

Publication number: CN102838977B
Application number: CN201210304769.3A
Authority: CN
Inventors: 宋华; 陈彦广; 李丹丹; 宋莹莹; 柳艳修
Original assignee: Northeast Petroleum University
Current assignee: Northeast Petroleum University
Priority date: 2012-08-25
Filing date: 2012-08-25
Publication date: 2015-04-15
Anticipated expiration: 2032-08-25
Also published as: CN102838977A

Abstract

Provided is a method for preparing a polyacrylamide solution for recycling oilfield produced water including Ca<2+> and Mg<2+>. The method comprises following steps: firstly, adding a 0.1 g/L-0.9 g/L treating agent into the oilfield produced water, mixing for 30 minutes -40 minutes, and standing for 30-60 minutes; and conventional filtration or centrifugal filtration, adding polyacrylamide to obtained water in the filtration, obtaining the polyacrylamide solution with the concentration of 1000 part per million-3000 part per million, and mixing for 2 hours. The treating agent is one kind or a mixture of several kinds of sodium carbonate, trisodium phosphate, disodium hydrogen phosphate, sodium tripolyphosphate, sodium hexametaphosphate, sodium oxalate, sodium pyrophosphate and sodium tetraborate. According to the method, the influence of the Ca<2+> and the Mg<2+> in the oilfield produced water on viscosity of the polyacrylamide solution is reduced, and then the problem that an oil displacement effect is poor or oil production cost is increased caused by reduction of the viscosity of the polyacrylamide solution is resolved.

Description

A kind of being used for contains Ca 2+and Mg 2+recycle of oil field produced water preparation polyacrylamide solution method

technical field:

The present invention relates to produced water disposal technical field in oil extraction process, being specifically related to a kind of for containing Ca ²⁺and Mg ²⁺recycle of oil field produced water preparation polyacrylamide solution method.

background technology:

Daqing oil field polymer flooding yearly rate-oil production has broken through ten million ton, and Daqing oil field tertiary oil recovery technology is large, with high content of technology, good in economic efficiency with its scale, creates the miracle in world's oil-field development history.Technique of polymer flooding has become Daqing oil field and has kept one of major measure of stable yields.Conventional flooding polymers mainly partially hydrolyzed polyacrylamide (HPAM) and derivative thereof.HPAM wetting ability is strong, and Yi Yushui forms hydrogen bond, soluble in water, has larger ydrodynamics volume, play viscosifying action after aquation.In order to Appropriate application oil field extracted water, fresh-water-saving resource, in order to the scheme of prepared polymer solution re-injection underground after domestic and international part oil field have employed and processes oil field extracted water.But containing a certain amount of Ca in oil field extracted water ²⁺, Mg ²⁺, Ba ²⁺, Sr ²⁺, Fe ²⁺deng divalent-metal ion, and the divalent ion in recovered water can be combined by the carboxyl in polyacrylamide amine molecule, produces flocculation, and forms precipitation, is easily separated, causes Viscosity of Polyacrylamide Solution significantly to reduce, and oil displacement efficiency is deteriorated; To keep its viscosity constant, then need the concentration improving polyacrylamide, displacement of reservoir oil cost will improve.Research finds in the divalent-metal ion in recovered water, Ca ²⁺and Mg ²⁺comparatively large on the impact of HPAM viscosity, and its content is higher.Therefore, develop one to be applicable to containing Ca ²⁺and Mg ²⁺the method of ion recycle of oil field produced water preparation polyacrylamide solution, ensures that polyacrylamide solution has viscosity higher retention rate, reduces oil field extracted water Ca ²⁺and Mg ²⁺the impact of ion pair polyacrylamide viscosity, has important economic implications to reduction oil extraction in oil field cost.

summary of the invention:

In order to solve Problems existing in background technology, the invention provides a kind of for containing Ca ²⁺and Mg ²⁺the method of recycle of oil field produced water preparation polyacrylamide solution, the present invention is by reducing Ca in oil field extracted water ²⁺and Mg ²⁺the impact of ion pair Viscosity of Polyacrylamide Solution, thus solve because Viscosity of Polyacrylamide Solution reduces the problem causing oil displacement efficiency variation or cost for oil production to improve.

The technical solution adopted in the present invention is: this is used for containing Ca ²⁺and Mg ²⁺recycle of oil field produced water preparation polyacrylamide solution method comprise the following steps: first in oil field extracted water, to add treatment agent, the concentration for the treatment of agent is 0.1g/L ~ 0.9g/L, stir 30 min ~ 40min, static 30 ~ 60 min, routine or centrifuging, filter in gained water and add polyacrylamide again, join concentration of polyacrylamide is the solution of 1000ppm ~ 3000ppm, stir 2h; Wherein treatment agent is one in sodium carbonate, tertiary sodium phosphate, Sodium phosphate dibasic, tripoly phosphate sodium STPP, Sodium hexametaphosphate 99, sodium oxalate, trisodium phosphate, sodium tetraborate or any several mixture.

The minimizing polyacrylamide that the present invention proposes is containing Ca ²⁺and Mg ²⁺the novel method of injection allocation water on the impact of Viscosity of Polyacrylamide Solution is by adding a kind of inorganic Ca in oil field extracted water ²⁺and Mg ²⁺metal ion treatment agent, by Ca ²⁺and Mg ²⁺polyacrylamide solution is prepared again, to improve Viscosity of Polyacrylamide Solution after removal.Ca in this treatment agent and oil field extracted water ²⁺and Mg ²⁺reaction produces precipitation, is separated, and through centrifugally filtering out throw out or precipitation, fundamentally removes Ca in water ²⁺and Mg ²⁺, reduce polyacrylamide and Ca ²⁺and Mg ²⁺act between metal ion, improve Viscosity of Polyacrylamide Solution retention rate.Thus realizing the object of the oil displacement efficiency improving polyacrylamide solution, the treatment agent used major part is Inorganic Chemicals, wide material sources, and cheap, preparing Viscosity of Polyacrylamide Solution after oil field produced water treatment can improve 15-30%.

embodiment:

Below in conjunction with embodiment, the present invention is further described:

embodiment 1,containing Ca ²⁺the experiment of Simulated Water

(1) with reference to simulation salt solution compound method (Hu Bozhong, " polymer flooding oil-extraction engineering ", petroleum industry press, 2004,235-235), preparation Ca ²⁺concentration is 50ppm, salinity is the Simulated Water of 4500ppm.

(2) getting sodium carbonate is added in Simulated Water, and wherein sodium carbonate adds and is respectively 0.13g/L, 0.26g/L, stirs 30min, static placement 3h.

(3) polyacrylamide (molecular weight 2,500 ten thousand is got, degree of hydrolysis 25%), join respectively in step (2) gained water with in blank Simulated Water, stir about 2h, join concentration of polyacrylamide is the solution of 2400ppm, by this solution in 45 DEG C of constant temperature 2h, measure the viscosity of this solution, and this viscosity is designated as initial viscosity.At continuing 45 DEG C, constant temperature measures the viscosity of solution respectively after 2 days, 2 weeks, one month.Experimental results is in table 1.As can be seen from Table 1, not adding viscosity behind month of HPAM during treatment agent is 54.6 mPas, and adding treatment agent concentration of sodium carbonate is 0.26g/L solution, and after one month, viscosity is 65.5mPas, and viscosity improves 20%.

Sodium carbonate addition is on impact (unit: the mPas) table 1 of Viscosity of Polyacrylamide Solution

embodiment 2,containing Mg ²⁺the experiment of Simulated Water

(1) with reference to simulation salt solution compound method (Hu Bozhong, " polymer flooding oil-extraction engineering ", petroleum industry press, 2004,235-235), preparation Mg ²⁺concentration is about 50ppm, salinity is the Simulated Water of about 4500ppm.

(2) getting tertiary sodium phosphate is added in Simulated Water, and wherein tertiary sodium phosphate dosage is respectively 0.39 g/L, 0.78 g/L, stirs 30min, static placement 3h.

(3) polyacrylamide (molecular weight 2,500 ten thousand is got, degree of hydrolysis 25%), join respectively in step (2) gained water with in blank Simulated Water, stir about 2h, join concentration of polyacrylamide is the solution of 2400ppm, by this solution in 45 DEG C of constant temperature 2h, measure the viscosity of this solution, and this viscosity is designated as initial viscosity.At continuing 45 DEG C, constant temperature measures the viscosity of solution respectively after 2 days, 2 weeks, one month.Experimental results is in table 2.As can be seen from Table 2, not adding viscosity behind month of HPAM during treatment agent is 53.7 mPas, and adding treatment agent tertiary sodium phosphate concentration is 0.78 g/L solution, and after one month, viscosity is 68.2 mPas, and viscosity improves 27.0%.

Tertiary sodium phosphate addition is on impact (unit: the mPas) table 2 of Viscosity of Polyacrylamide Solution

embodiment 3,containing Ca ²⁺and Mg ²⁺oil field actual recovered water experiment

Experimental procedure is as follows:

(1) get the recovered water that certain oil recovery factory, oil field is representative, after biochemical treatment, Analysis Results of Water Quality is Ca ²⁺concentration is 57.72 mg/L, Mg ²⁺concentration is 32.08mg/L, and salinity is 4787.45 mg/L.

(2) get tripoly phosphate sodium STPP respectively and sodium oxalate is added in Simulated Water, wherein tripoly phosphate sodium STPP and sodium oxalate dosage are respectively 0.48 g/L, 0.14g/L, stir 30min, static placement 3h.

(3) polyacrylamide (molecular weight 2,500 ten thousand is got, degree of hydrolysis 25%), join respectively in step (2) gained water with in blank Simulated Water, stir about 2h, join concentration of polyacrylamide is the solution of 2400ppm, by this solution in 45 DEG C of constant temperature 2h, measure the viscosity of this solution, and this viscosity is designated as initial viscosity.At continuing 45 DEG C, constant temperature measures the viscosity of solution respectively after 2 days, 2 weeks, one month.Experimental results is in table 3.As can be seen from Table 3, when not adding treatment agent, after one month, HPAM soltion viscosity is 47.0 mPas; After adding treatment agent, after one month, HPAM soltion viscosity is 54.7 mPas, and viscosity improves 16%.

Tripoly phosphate sodium STPP and oxalic acid addition are on impact (unit: the mPas) table 3 of Viscosity of Polyacrylamide Solution

Claims

1. one kind for containing Ca ²⁺and Mg ²⁺recycle of oil field produced water preparation polyacrylamide solution method, comprise the following steps: first in oil field extracted water, to add inorganic agent, the concentration of inorganic agent is 0.1g/L ~ 0.9g/L, stir 30 min ~ 40min, static 30 ~ 60 min, conventional or centrifuging, filters in gained water and adds polyacrylamide again, join concentration of polyacrylamide is the solution of 1000ppm ~ 3000ppm, stir 2h; Wherein treatment agent is one in sodium carbonate, tertiary sodium phosphate, Sodium phosphate dibasic, tripoly phosphate sodium STPP, Sodium hexametaphosphate 99, sodium oxalate, trisodium phosphate, sodium tetraborate or any several mixture.