| abstract |
This diverting agent contains a polyvinyl alcohol resin, and is added to a 0.48 mass% aqueous solution of guar gum to prepare a mixed solution having a concentration of 12 mass%. The mixed solution is dispersed for 60 minutes at 30°C to produce a dispersion, which is subjected to pressurized dewatering under a pressure of 1 MPa using a pressurization dewatering device equipped with a drainage portion having a 2-mm wide slit. When the regression line expressed by formula (A): y = ax + b was calculated by the method of least squares from a scatter plot in which the horizontal axis is the square root of time x and the vertical axis is the cumulative dewatering amount y (in formula (A), y represents the cumulative dewatering amount (g), x represents the square root of the time (min) elapsed from the start of pressurization, a and b represent the slope and intercept of the regression line, and 0 < x ≤ 2), the slope a of formula (A) meets condition (B): a ≤ 80. |