Barium-sulfate scale deposition inhibitor, method for inhibiting barium-sulfate scale deposition, and barium-sulfate scale deposition inhibitor composition
Provided are a barium-sulfate scale inhibitor and a barium-sulfate scale inhibitor composition each of which can express a high barium-sulfate scale-inhibiting ability. Also provided is a method of inhibiting a barium-sulfate scale that can express a high barium-sulfate scale-inhibiting ability. The barium-sulfate scale inhibitor of the present invention includes a sulfonic acid group-containing copolymer obtained by polymerizing a monomer composition containing a carboxyl group-containing monomer and a sulfonic acid group-containing monomer, in which when the barium-sulfate scale inhibitor is added at a solid content concentration of 1 wt % to high-salt-concentration water having a metal salt concentration of 10 wt % or more, the sulfonic acid group-containing copolymer is free from precipitating.
1. A barium-sulfate scale inhibitor, comprising a sulfonic acid group-containing copolymer obtained by polymerizing a monomer composition containing a carboxyl group-containing monomer and a sulfonic acid group-containing monomer,
wherein a content ratio “carboxyl group-containing monomer/sulfonic acid group-containing monomer” of the carboxyl group-containing monomer to the sulfonic acid group-containing monomer is from 71/29 to 98/2 in terms of a weight ratio,
wherein the sulfonic acid group-containing monomer comprises a sulfonic acid group-containing ether compound represented by the general formula (1):
in the general formula (1), R 1 represents any one of a single bond, CH 2 , and CH 2 CH 2 , R 2 represents any one of H and CH 3 , and one of X and Y represents a hydroxyl group, and another thereof represents a sulfonic acid (salt) group, and
wherein when the barium-sulfate scale inhibitor is added at a solid content concentration of 1 wt % to high-salt-concentration water having a metal salt concentration of 10 wt % or more, the sulfonic acid group-containing copolymer is free from precipitating.
2. A method of inhibiting formation of a barium sulfate scale in a drilling pipe in crude oil drilling, the method comprising adding, to the drilling pipe, barium-sulfate scale inhibitor, comprising a sulfonic acid group-containing copolymer obtained by polymerizing a monomer composition containing a carboxyl group-containing monomer and a sulfonic acid group-containing monomer, wherein a content ratio “carboxyl group-containing monomer/sulfonic acid group-containing monomer” of the carboxyl group-containing monomer to the sulfonic acid group-containing monomer is from 71/29 to 98/2 in terms of a weight ratio, wherein the sulfonic acid group-containing monomer comprises a sulfonic acid group-containing ether compound represented by the general formula (1):
in the general formula (1), R 1 represents any one of a single bond, CH 2 , and CH 2 , R 2 represents any one of H and CH 3 , and one of X and Y represents a hydroxyl group, and another thereof represents a sulfonic acid (salt) group, and
wherein when the barium-sulfate scale inhibitor is added at a solid content concentration of 1 wt % to high-salt-concentration water having a metal salt concentration of 10 wt % or more, the sulfonic acid group-containing copolymer is free from precipitating.
3. The method of inhibiting a barium-sulfate scale according to claim 2 , wherein the barium-sulfate scale inhibitor is added to the high-salt-concentration water present in the drilling pipe so that a concentration of the barium-sulfate scale inhibitor is from 0.1 ppm to 1,000 ppm in terms of a solid content.
4. A barium-sulfate scale inhibitor composition, comprising:
water; and
a sulfonic acid group-containing copolymer obtained by polymerizing a monomer composition containing a carboxyl group-containing monomer and a sulfonic acid group-containing monomer, wherein a content ratio “carboxyl group-containing monomer/sulfonic acid group-containing monomer” of the carboxyl group-containing monomer to the sulfonic acid group-containing monomer is from 71/29 to 98/2 in terms of a weight ratio, wherein the sulfonic acid group-containing monomer comprises a sulfonic acid group-containing ether compound represented by the general formula (1):
in the general formula (1), R 1 represents any one of a single bond, CH 2 , and CH 2 , R 2 represents any one of H and CH 3 , and one of X and Y represents a hydroxyl group, and another thereof represents a sulfonic acid (salt) group, and
wherein when the barium-sulfate scale inhibitor is added at a solid content concentration of 1 wt % to high-salt-concentration water having a metal salt concentration of 10 wt % or more, the sulfonic acid group-containing copolymer is free from precipitating.
5. The barium-sulfate scale inhibitor composition according to claim 4 , wherein a content of the sulfonic acid group-containing copolymer in the barium-sulfate scale inhibitor composition with respect to the water is from 0.1 ppm to 1,000 ppm in terms of a solid content.