Preparation of Polymer Solution for Profile Control and Displacement Using Wastewater with High Ca2+/Mg2+ and Fe2+ Concentrations

Abstract

In the present study, we used Kalamkas, which is a typical Kazakhstani oilfield, which produces wastewater with high Ca2+/Mg2+ and Fe2+ concentrations, as a case study. We investigated a method for preparing Fe2+ polymer solutions without oxygen isolation under the conditions of salinity > 110 × 103 mg/L, Ca2+/Mg2+ concentration ˃ 7000 mg/L, and Fe2+ concentration ˃ 30 mg/L. Fe2+-resistant groups were grafted onto the molecular chains of a hydrophobically associating polymer prepared using existing synthesis technology to overcome the decrease in apparent viscosity of the polymer solution due to the oxidation of Fe2+ during solution preparation. The experiments showed that PAM-IR with iron-resistant groups can be completely dissolved in the wastewater within 180 min, and can tolerate an NaCl concentration of up to 0.23 × 106 mg/L, a Ca2+ concentration of up to 10 × 103 mg/L, an Mg2+ concentration of up to 9 × 103 mg/L, and a Fe2+ concentration of up to 90 mg/L, with favorable thickening performance and resistances to NaCl, Ca2+, Mg2+, and Fe2+. PAM-IR has good injection performance and can establish a high resistance factor (FR) and residual resistance factor (FRR) to increase the sweep efficiency. Therefore, it is potentially useful for enhancing oil recovery.

Synthesis and salt resistance of non-ionic polymer P (AM/ APEG400/NVP/SM)

“…Hydrophobically associating polymer [8][9][10], as a new type of water-soluble polymer with a small number of hydrophobic groups introduced into the macromolecular chain of the polymer, has become one of the hot spots in the research of polymer materials in the past 30 years. With the deepening of research and the practice verification, it has successfully applied in the pilot test and large-scale application of EOR in oilfield chemical flooding, and has excellent potential in EOR application [11][12][13].…”