英文文献.docx

1、英文文献Method of continuous dissolution of polyacrylamide emulsions for enhanced oil recovery (EOR)EP 2283915 A1AbstractEnhanced oil recovery method consisting in continuously dissolving, in the injection water, a stable invert emulsion of acrylamide (co)polymer containing at least one inverting agent,

2、 and a water soluble polymer, whereby:- in a first step, the emulsion is prediluted in a first static mixer to a (co)polymer concentration of at least 5 g/l, the difference of pressure between the mixer outlet and inlet being at least 2 bar,- in a second step, the suspension from the first mixer is

3、diluted in a second static mixer to a concentration corresponding to the injection concentration of the water in the well of between 500 and 3000 ppm, the difference of pressure between the mixer outlet and inlet being at least 1 bar.Claims1. Enhanced oil recovery method consisting in continuously d

4、issolving, in the injection water, a stable invert emulsion of acrylamide (co)polymer containing at least one inverting agent, whereby:- in a first step, the emulsion is prediluted in a first static mixer mounted on a bypass of the main injection water circuit, to a (co)polymer concentration of at l

5、east 5 g/l, the difference of pressure between the mixer outlet and inlet being at least 2 bars,- in a second step, the dispersion mixture from the first mixer is diluted in a second static mixer mounted on the main injection water circuit, to a concentration corresponding to the injection concentra

6、tion of the water in the well of between 500 and 3000 ppm, the difference of pressure between the mixer outlet and inlet being at least 1 bar.2. Method according to Claim 1, characterized in that the (co)polymer concentration in the first step is between 5 and 20 g/l, advantageously about 20 g/l.3.

7、Method according to Claim 1, characterized in that the difference of pressure between the outlet and inlet of the first mixer is between 2 and 10 bars, advantageously 10 bars.4. Method according to Claim 1, characterized in that the difference of pressure between the outlet and inlet of the second m

8、ixer is between 1 and 3 bars, advantageously 3 bars.5. Method according to Claim 1, characterized in that the injection water flow rate in the main circuit is between 100 and 200 m3/h at a pressure of between 40 and 200 bars governed by the field pressure.6. Method according to Claim 1, characterize

9、d in that the (co)polymer content in the invert emulsion before predilution is between 20 and 50%.7. Installation implementing the method according to one of Claims 1 to 6.Description 0001 Polyacrylamides are produced industrially in various forms: powders, water-in-oil emulsions, polymerized beads

10、in suspension, water-in-water emulsions, aqueous solutions, water-alcohol suspensions, etc. 0002 These polymers may have similar physicochemical properties and are usually selected on two criteria:o Cost and, in this case, powders are selected,o Their ease of handling and, despite higher costs, emul

11、sions are selected. 0003 These emulsions were discovered in 1957 by J.W. Vanderhoff and R.M. Wiley (USP 3 284 393 ). 0004 These early emulsions contained microparticles of polymers emulsified in an oil by means of one or more surface active agents having a low HLB (hydrophilic-hydrophobic balance) o

12、f about 2 to 6. For these emulsions having such composition, , it was very difficult to dilute the polymer microgels directly in a solution. Indead, the dissolution water have difficulties to penetrate the surface active agents barriers. 0005 They were therefore usually dried by spray drying to yiel

13、d a powder which dissolved more or less satisfactorily. 0006 In 1970, D.R. Anderson and A.J. Frisque (patent USP 3 624 019 ) discovered that it was possible to invert these emulsions, by adding a hydrophilic surface active agent (HLB8). This rather hydrophilic surface active agent enabled the water

14、to penetrate into the polymer spherical microparticule and to dissolve it in a few minutes. 0007 Initially, this surface active agent was delivered and added separately to the dilution water. 0008 But very quickly, the production companies developed formulations in which it was possible to incorpora

15、te inverting surface active agents in the emulsion itself, without latter coagulating or being destabilized. 0009 This operation was a real technical challenge because required quantity of hydrophilic surface active agent added was limited by coagulation or destabilization either during production o

16、r in storage. 0010 The industrial implementation of this method was the subject of considerable successive researches and numerous patents. 0011 However, even today, limitation to properly invert an emulsion exist, with two main factors:o The quantity of hydrophilic surface active agent the system c

17、an sustainto avoid coagulation of the emulsion during production or in storage,o The concentration of polymer reached when dissolving the emulsion in water. 0012 It is commonly found that the maximum quantity of hydrophilic surface active agent, all systems combined, compatible with the stability of

18、 the emulsion, is about 5% of the emulsion. 0013 This quantity is the one observed with the most effective NPD (ethoxylated nonylphenol 9 EO) surface active agents or ethoxylated alcohols containing 7-9 EO. Larger quantities of less effective surface active agents can be added, but without improving

19、 the dissolution. 0014 With such a concentration of reversing surface active agents, it is found that the emulsion cannot dissolve completely in the water in less than 5 minutes, in an emulsion concentration lower than 9-12 grams/litre or on standard commercial emulsions, about 4-5 grams/litre (4 to

20、 5000 ppm) of active polymer.Particular case of enhanced oil recovery 0015 Due to the product costs, EOR mainly uses powders to viscosify the water injected into the oil wells. These polyacrylamide powders are dissolved to a final concentration of 500 to 2000 ppm for injection into the oil well at t

21、he field pressure. 0016 In certain cases, and particularly when the product is used on boats (FPSO) or offshore platforms, the handling of very large quantities of powder between a service boat and the FPSO or the platform raises severe limitations associated with air lift transport, difficult to so

22、lve today. 0017 In these situations, the end-usersprefer to use an emulsion that is easier to transfer by standard offshore pumping means. 0018 The requirements of the end-users are very strict: total dissolution in less than 5 minutes, completely and continuously. 0019 It is therefore necessary to

23、dissolve the emulsion to a final concentration of 500 to 2000 ppm in a pipe in line, which cannot be obtained with a stable emulsion incorporated with a inverting surface active agent in concentrations ensuring the stability thereof. 0020 The test accordingly used consists in measuring the time take

24、n by given volumes of solution containing 1000 ppm of active polymer to flow through a filter. The solution is contained in a cell pressurized to 2 bars and the filter has a diameter of 47 mm and a pore size of 5 microns. 0021 The times required to obtain 100 ml (t100ml); 200 ml (t200ml) and 300 ml

25、(t300ml) of filtrate are therefore measured and a filtration quotient (or filter ratio denoted FR) is defined, expressed by: FR = t 300 ml - t 200 ml t 200 ml - t 100 ml 0022 The time measurement accuracy is 0.1 second. 0023 The FR thus represents the capacity of the polymer solution to plug the fil

26、ter for two equivalent consecutive volumes. A typical acceptability criterion of the industry is FR 1.5. 0024 It is clear that this level of filterability cannot be reached even after several hours of stirring in the laboratory, and even less in industrial conditions for the desired concentrations o

27、f 500 and 2000 ppm. 0025 The usual solution is to further incorporate a NP9 type (nonylphenol 9 EO) surface active agent or ethoxylated or alkoxylated alcohol or dioctylsulphosuccinate or other anionic surface active agent in a proportion far above 5% in the dilution water. In these conditions, the

28、emulsion may pass the filterability test. 0026 This solution is difficult to accept by the user because:o Two different chemicals must be handled and stored in difficult conditions,addying a non-negligible investment cost,o The cost of the surface active agent possibly jeopardises the profitability

29、of the project. 0027 To sum up, willing to implement the use invert emulsions today, a person skilled in the art has therefore the choice between:o the further addition of inverting surface active agent with the abovementioned drawbacks;o large scale continuous or batch installations allowing long r

30、esidence time, implying high costs in investment, volume and maintenance. 0028 The invention refers to a method for dissolving, in line and continuously, a reverse emulsion of acrylamide (co)polymer to the active polymer injection concentration of 500 to 2000 ppm, in order to obtain the filterabilit

31、y lower than 1.5 in less than 5 minutes of mixing contact time. 0029 For this purpose, the applicant has developed a 2-phases in line dissolution:o A in line dispersion phase at high concentration,o A subsequent in line dilution phase at the final desired concentration. 0030 More precisely, the inve

32、ntion relates to an enhanced oil recovery method consisting in continuously dissolving a stable invert emulsion of acrylamide (co)polymer containing at least one inverting agent, whereby:o in a first step, the emulsion is prediluted in a first static mixer mounted on a bypass of the main injection water circuit, to a (co)polymer concentration of at least 5 g/l, preferably between 5 and 20 g/l, advantageously ab