1416
LEBEDEVA et al.
(concentration of glycol ether 10 wt %; reagent vol-
ume 15% of the pore volume):
Glycol EGMBE EGMHE TEGMME TEGMPE TEGMHE
ether
K , %
18.0
11.8
2.2
24.8
7.0
o
It is seen that TEGMPE and EGMBE show the
best performance. Apparently, 4 5 carbon atoms in
the alkyl group are sufficient to ensure the maximal
compatibility of a solution being pumped-in and re-
sidual oil in the stratum model and its efficient dis-
placement. With longer alkyl radicals, the solubility
of an ether in oil becomes the prevailing factor, which
results in retention of oil in the stratum model. On
the whole, triethylene glycol ethers show a higher oil-
displacing power owing to higher hydrophilicity.
The performance of formulations used for oil re-
covery is usually associated with a decrease in the
interphase tension at the aqueous phase oil boundary.
Using a stalagmometer, we determined the interphase
tension at the boundary between aqueous solution of
glycol and kerosene. As seen from Figs. 1a and 1b,
the interphase tension decreases on adding glycol
ethers to water (1 or 10%). However, there is no un-
ambiguous correlation between the interphase tension
and performance of ethers in intensification of oil
recovery. For example, TEGMHE considerably de-
creases the interphase tension but shows poor per-
formance in oil displacement. In acid treatment, it is
adsorbed on the particle surface and makes it more
hydrophobic, decreasing the efficiency of reaction of
acid with the rock; in oil displacement, it readily
mixes with residual oil, is adsorbed on the rock, and
is not displaced by liquid. The minimal interphase
tension is observed with a 10% solution of EGMBE,
though it is not the best oil-displacing agent. Thus,
along with interphase tension, some other factors may
Fig. 1. Influence of the structure of (a) ethylene glycol and
(b) triethylene glycol ethers on the interphase tension
at the water kerosene boundary. (n) Number of atoms in
the alkyl group of glycol ether. Concentration of glycol
ether, wt %: (1) 1 and (2) 10.
increases. The performance of an acid formulation
depends on the structure of ether, namely, on the
length of the hydrocarbon radical and the number of
oxyethyl units. The breakdown of the carbonate rock
was the fastest with ethers containing 4 5 carbon
atoms in the alkyl group. Apparently, glycol ethers
with short alkyl group dissolve oil to a lesser extent,
and ethers with long alkyl group are worse miscible
with the aqueous phase. Owing to their better com-
patibility with water and oil, triethylene glycol ethers be significant, e.g., compatibility of ethers with the
accelerate breakdown of the oil-saturated model rock
at any length of the alkyl radical.
aqueous and organic phases.
CONCLUSIONS
Similar trends were obtained in studying the oil-
displacing power of ether. A special column modeling
an oil stratum was charged with crushed rock and
brought to required temperature, after which water,
oil, and again water were successively fed until the
oil displacement stopped (at a constant rate of filtra-
tion of the liquids). From the volume of displaced oil
we calculated the oil displacement factor Ko equal to
the fraction of oil displaced from the column with
water. After that, an aqueous solution of glycol ether
was fed. Below are given the values Ko by which the
oil displacement factor increased on adding glycol
(1) Ethylene glycol monoheptyl ether and triethyl-
ene glycol monomethyl, monopentyl, and monoheptyl
ethers were prepared and tested for intensification of
oil recovery.
(2) Glycol ethers accelerate breakdown of oil-
saturated calcium carbonate with acid formulations
owing to washing-out of oil. The breakdown rate
depends on the structure of an ether. The highest per-
formance is shown by glycols containing 4 5 carbon
atoms in the alkyl group.
RUSSIAN JOURNAL OF APPLIED CHEMISTRY Vol. 74 No. 8 2001
Lebedeva
