SU1090264A3 - Emulsifier for preparing microemulsions - Google Patents

Abstract

A microemulsion comprises a mixture of water containing an excess of 60 g/l of mono- and divalent salts, a hydrocarbon, an amphoteric surfactant of the formula: <IMAGE> wherein m is a whole number ranging from 1 to 5, inclusive, n is a whole number ranging from 1 to 22 inclusive, X<-> is a member selected from the group consisting of COO<->, SO3 and a sulphonated ethylene polyoxide, and R1 and R2 are hydrocarbon groups containing from 1 to 22 carbon atoms and a co- surfactant comprising at least one C1 to C10 alcohol. This microemulsion may be used for recovering petroleum in beds containing water of high salinity.

Description

The invention relates to the development of oil fields using microemulsions for formations with high salinity of formation waters. It is known to obtain micro-emulsions with distilled water and hydrocarbons containing surfactant and co-surfactants p. A known emulsifier for the preparation of microemulsions used to extract oil based on coenzide surfactant (co-surfactant) is G2. A disadvantage of the known microemul is that both of these types of surface-active ion exchangers react in a highly concentrated salt medium with the risk of precipitating, but are adsorbed on the mineral particles. The purpose of the invention is to increase the stability of a microemulsion with an elevated salt content in reservoir waters. This goal is achieved by the fact that the emulsifier for the preparation of microemulsions used to extract oil on the basis of surfactant and codenside, as a surfactant, it contains a compound of the general formula CHg-COOKa where R is an alkyl chain with carbon distribution corresponding to fatty acids of carbon, acids with carbonic acids chains from C ;, to C, and the volume ratio of surfactant to codenside is 1: (O, 5-4.5). A mixture of i-hexanol, n-octanol and isopropanol is used as a coenzide. An amphoteric surfactant belonging to the group of alkyl betaines, α-amphosol can be represented by the following general formula R-N-CHj-COgNa CHt 41 where R is the residual residue of copra fatty acid. Copra fatty acids are a mixture of acids with different chain lengths from C to C wt.%: Cj7.8-9.5, 5-9.7 44-51 13-18.5, 5-10.5 (exemplary) 1-3 (unsaturated) 6-10.8 The surfactants are selected from the group of alcohols with, depending on their distribution coefficient between the water and the hydrocarbon component of the microemulsion. To study the stability of microemulsions, mixtures are prepared that include an amphoteric surfactant; co-surfactants having the structure of alcohols; hydrocarbon: crude oil, petroleum fraction - gas oil - keosin, or refined crude oil fraction, or liquefied gas; water containing mono- or divalent ions with a concentration greater than 60 g / l. For comparison of the formation of micromulsions in saline media, take an emulsifier with a classical anionic surfactant. Emulsifier (1) containing surfactant Hz BN-CH2-C02lfaCl, de R-Su ((} (copa fatty acids), codenzide,%: Isopropanol 72 n-Hexanol 14 n-Octanol 14 Emulsifier (2) containing surfactant sodium auryl sulfonate, codenzide, %: Isopropanol 72 N-Hexanol 14 H-Octanol14 Aslo-dodecane Table 1 shows the results of microamulsion stability with oil in a highly salty medium, especially in the presence of divalent ions even at high temperatures. C is a surfactant and a surfactant; E is water from a deposit; P - hydrocarbon. Each built-up section to the curve shows that the area of homogeneous solutions or microemulsions is located above it, and the area of multiphase composition below it. Ex. 1. Water from the field site containing 200 g / l of NaCfc; - dodecane and surfactants with the alkylbetaine structure, where R is the copra radical in an aqueous solution containing 25% of the active substance and 18% isopropanol; the co-surfactant substances are n-hexanol and H-octanol mixed in a 50-50 volume ratio. The volume ratio of surfactant to codenzide varies from 0.1 to 1.5, preferably in the range of 0.5-1.0. The microemulsion is prepared as a simple mixture of field water, a dodec as a hydrocarbon, a mixture of surfactant and codenside. The curve in the diagram (figure 1) shows that it is possible to obtain an extensive range of microemulsions from water from fields with 200 g of NaC per liter of dodecane that are stable in time and at 80 C. Example 2. The triple diagram (figure 2) defines the region of existence microemulsions formed and water with 100 g / l of SASS dodecane AND the same systems of surfactants and alcohols described in example 1. Example 3. The diagram (Fig. 3) defines the region of existence of microemulsions formed from water with an average salt content 60 g / l NaCt and 15 g / l CaCl, dodecane and mixtures of amphosol in an aqueous 35% plant thief with isopropanol and hexanol mixed in 1/3 - 2/3 volume ratios. The ratio of surfactant / alcohols vary from 0.25 to 4.5. The stability of microemulsions is as good as in previous cases. Example 4. The diagram (figure 4) defines the region of existence of stable microemulsions and resistance to heat, which can be obtained from water from a deposit with a high salt content of 100 g / l NaCt and 20 g / l CaCl, dodecane and surfactant system - alcohols, as indicated in Example 3. The surfactant / alcohols volume ratio is 0.30-4.50. The following are the compositions of microemulsions according to examples 1-4. Table 2 lists the weight percentages of points located on the solution splitting curve for the corresponding maximum ionic forces. Thus, lambs prepared using this emulsifier are resistant to highly saline water and elevated reservoir temperature. Table 1

58.9

0.5

one

3

4.5

60,8

0.5

one

3

4.5

80

200

f + + f

f

100

table 2

8,658,932,5

22.238,639.2

31,323,345,4

49,415,934,7

57.54,837,7

9,160,830,1

21,537,640,9

32,824,642,6 45,314,640,1

54.94,640,5

Continued table. one

Emulsifier

Continued table. 2

10,067,422,6

27.747,225.1 37.027.036.0

49,615,734,7 59,34,835,9

10,768,520,8

28.846,924.3

39.7.27,632.7 51,515,533.0 60.34,735.0

Claims (2)

1. EMULSIFIER FOR PREPARATION OF MICROEMULSIONS used to extract oil based on a surfactant and a cotenzide; characterized in that, in order to increase the stability of the microemulsion with a high content of salts in the formation water, c. as a surfactant, it contains a compound of the general formula RH xCHZ ^X CH ₃ SG CHz-COONO where R is an alkyl chain with a carbon distribution corresponding to copra fatty acids, acids with carbon chains from D ° C44, and the volumetric ratio of surfactant to coenzid is 1: (0.5-4.5). 2. The emulsifier according to claim 1, wherein the mixture of N-hexanol, K-octanol and isopropanol is used as the co-benzide. M / uumMMAMADLAALADO. FIG. 1