Aqueous injection fluid and method for sulfate scale inhibition in subterranean formations
An aqueous injection fluid for treatment of a subterranean hydrocarbon-bearing formation includes water and at least one water soluble cationic surfactant having a general formula (DCS): where ‘R’ is C 2 -C 4 alkylene which may have one or more —O—, —S— or —S(O) 2 O— groups, ‘X − ’ is halide, ‘x’ is an integer of from 2 to 10 and, ‘y’ is an integer of from 2 to 10.
1 . A method for inhibiting sulphate scale formation in a well-bore disposed in a hydrocarbon-bearing subterranean formation, comprising:
injecting into the well-bore an aqueous injection fluid comprising:
water, and
at least one water soluble cationic surfactant having a general formula (DCS):
wherein R is C 2 -C 4 alkylene which may have one or more —O—, —S— or —S(O) 2 O— groups;
X − is halide;
x is an integer of from 2 to 10; and
y is an integer of from 2 to 10.
2 . The method according to claim 1 , wherein the water is at least one selected from the group consisting of fresh water, seawater, brackish water, and formation water.
3 . The method according to claim 1 , wherein the aqueous injection fluid has a total dissolved solids content of at least about 50,000 parts per million by weight.
4 . The method according to claim 1 , wherein the aqueous injection fluid has a total dissolved solids content of from about 50,000 to about 300,000 parts per million by weight.
5 . The method according to claim 1 , wherein the water soluble cationic surfactant (DCS) has a critical micelle concentration of from about 0.015 to about 0.025 mmolL −1 .
6 . The method according to claim 1 , wherein the water soluble cationic surfactant (DCS) has a thermal degradation temperature of at least about 250° C., as determined by Thermogravimetric Analysis.
7 . The method according to claim 1 , wherein the water soluble cationic surfactant (DCS) has a thermal degradation temperature of from about 250° C. to about 300° C., as determined by Thermogravimetric Analysis.
8 . The method according to claim 1 , wherein the water soluble cationic surfactant (DCS) has a thermal degradation temperature of from about 270° C. to about 300° C., as determined by Thermogravimetric Analysis.
9 . The method according to claim 1 , wherein the aqueous injection a concentration of the at least one water soluble cationic surfactant (DCS) is from about 50 to about 2,500 parts per million by weight.
10 . The method according to claim 1 , wherein the aqueous injection fluid a concentration of the at least one water soluble cationic surfactant (DCS) is from about 50 to about, 1500 parts per million by weight.
11 . The method according to claim 1 , wherein
R is C 2 -C 4 alkylene;
X − is Cl − or Br − ;
x is an integer of from 3 to 10; and
y is an integer of from 3 to 10.
12 . The method according to claim 11 , wherein X − is Br − .
13 . The method according to claim 1 , wherein:
R is C 2 -C 4 alkylene which is interrupted by —O—;
X − is Cl − or Br − ;
x is an integer of from 3 to 10; and,
y is in an integer of from 3 to 10.
14 . The method according to claim 13 , wherein X − is Br − .
15 . The method according to claim 1 , wherein the well-bore has a static bottom hole temperature of at least about 100° C.
16 . The method according to claim 1 , wherein the well-bore has a static bottom hole temperature of at least about 150° C.
17 . The method according to claim 1 , wherein the well-bore has a bottom hole pressure of at least about 69 MPa.
18 . The method according to claim 1 , wherein the well-bore has a bottom hole pressure of from about 69 to about 138 MPa.