Low molecular weight poly(acrylic acid) as a salt scaling inhibitor in oilfield operations

Abstract

Poly(acrylic acid) (PAA) samples with molecular weights between 820 and 2950 were synthesized by a solution polymerization process using an initiating redox system. The obtained PAAs were then screened for their ability to inhibit salt scale formation. In this screening system, salt scale was formed by injecting pit water into the oil. The salt scale inhibition efficiency was higher for PAAs at a higher concentration and for lower molecular weight PAAs. A reduction of pH, extension of stirring time, or an increase in temperature caused the inhibition efficiency of the PAAs to drop. An optimal inhibition efficiency of 98.70% was observed using a PAA with a molecular weight of 820 at a concentration of 20 ppm, at 20 °C, while being stirred for 1 h at a pH of 6.029.

Performance of inhibitors on CaCO3 scale deposition in stainless steel & copper pipe surface

“…Polyacrylates with molecular weight in the range of 500-6000 are the most widely used due to their high scale inhibition power and environmental compatibility [16][17][18]. Polymers are generally of low molecular weight to prevent bridging of suspended solids, but of sufficient structure to adhere to developed scale formation i.e.…”

Antiscaling properties of novel maleic‐anhydride copolymers prepared via iron (II) – chloride mediated ATRP

“…It is a well known fact that the polymers which are effective anti‐precipitants and de‐scalants are of relatively low molecular weight, i.e., below 10,000 and preferably in between 500 and 4000 . Polymers are generally of low molecular weight to prevent bridging of suspended solids, but of sufficient structure to adhere to developed scale formation i.e., they can be adsorbed onto the active growth sites of the crystal surface, and disturb the regular outgrowth of CaCO 3 or CaSO 4 crystal …”

Application and evaluation of novel acrylic based CaSO4 inhibitors for pipes

“…With an increase in antiscalant molecular weight from 580 to 2000 the scale mass decreases from 0.1967 kg/m 2 to 0.0119 kg/m 2 for copper pipe and 0.2139 kg/m 2 to 0.0029 kg/m 2 for steel pipe. We already know that the polymers which are effective anti-scalants are of relatively low molecular weight, preferably in between 500 and 4000 [16][17][18]. Polymers are generally of low molecular weight to prevent bridging of suspended solids, but they should be of sufficient structure (length of about 10-15 repeating unit is best) to adhere to developed scale formation i.e.…”

“…below 10,000 [6,15] and preferably in between 500 and 4000 [16][17][18]. To account for this behavior one can recall that the chains of most linear and atactic polymers, devoid of secondary and tertiary structures, tend to fold within each other to form a mass of interpenetrating random coils, and this tendency increases as the polymer size increases.…”