Gelation Study on a Hydrophobically Associating Polymer/Polyethylenimine Gel System for Water Shut-off Treatment

Abstract

A gel system has been widely used in many mature oilfields for water shut-off treatment. In the present study, the hydrophobically associating polymer (HAP) was cross-linked with the polyethylenimine (PEI) to form a HAP/PEI gel system which contains 0.35 wt % HAP and 0.60 wt % PEI. Gelation behaviors of the HAP/PEI gel formed in bottle and in core were studied, respectively. Results show that the gelation behaviors of the gel system were greatly affected by the concentration of HAP and that of PEI. The addition of the sodium chloride or calcium chloride generally resulted in a decrease of the apparent viscosity and an extension of the gelation time. However, a low concentration of sodium chloride led to a slight increase of the gel viscosity in bottle due to the intensification of the hydrophobic association. The rock skeleton of the core had a great effect on the gelation behavior. Compared with the results obtained in bottle, the apparent viscosity of the HAP/PEI gel system in core was obviously reduced, and the gelation time in core was extended two times or even longer. Both the gelation times achieved in bottle and in core decreased with the increase of temperature following the relationship of Arrhenius-type. The activation energy of the HAP/PEI gel system was 41.57 kJ/mol in bottle but increased to 60.95 kJ/mol in core. Data collected from the core flowing tests present a favorable shut-off performance and a strong wash-out resistance of the HAP/PEI gel system. In addition, the in-depth flow diversion and water permeability reduction were two main mechanisms of this gel system for water shut-off treatment.

Synthesis, characterization and evaluation of polyacrylamide graft starch/clay nanocomposite hydrogel system for enhanced oil recovery

“…The bottle test method is a semiquantitative measurement of gelation time, and it can also be considered as a fast and inexpensive method to study the gelation kinetics over a wide range of chemical formulations (Dai et al 2014;Yadav and Mahto 2012). The gelation time of water shutoff gel was considered the period of time when the gelling solution in a code A state turns to a flowing gel code C state (Bai et al 2015). In this method, the gelation process was investigated at frequent time intervals by tilting the bottles to observe the gel flow behavior under the influence of gravity.…”

Self-assembly properties of a temperature- and salt-tolerant amphoteric hydrophobically associating polyacrylamide

“…These side chains form hydrophobic microdomains in solution because of hydrophobic association, which leads to intramolecular and intermolecular associations. [6][7][8] In order to tolerate reservoir conditions, which are typically severe, new polymers have been designed and synthesized to achieve improved properties; these new polymers have included hydrophobically associating polymers, hyperbranched polymers, amphoteric polymers, star polymers, etc. At copolymer concentrations greater than the critical association concentration (CAC), macromolecules have an increased tendency to associate intermolecularly and can as a result form a supramolecular network.…”

A novel temperature‐tolerant foamed resin for enhanced oil recovery

“…[28][29][30] The prepolymer sample used in the static performance evaluation was "butyl acetate+S3. [28][29][30] The prepolymer sample used in the static performance evaluation was "butyl acetate+S3.…”