Influence of polymer structure on the gelation kinetics and gel strength of acrylamide-based copolymers, bentonite and polyethylenimine systems for conformance control of oil reservoirs

2019 ◽  
Vol 136 (22) ◽  
pp. 47556 ◽  
Author(s):  
Fernanda G. C. Tessarolli ◽  
Sara T. S. Souza ◽  
Ailton S. Gomes ◽  
Claudia R. E. Mansur
Keyword(s):  
Polymer Structure ◽  
Gel Strength ◽  
Oil Reservoirs ◽  
Conformance Control ◽  
Gelation Kinetics

scholarly journals Gelation Kinetics of Hydrogels Based on Acrylamide–AMPS–NVP Terpolymer, Bentonite, and Polyethylenimine for Conformance Control of Oil Reservoirs

Gels ◽  
2019 ◽  
Vol 5 (1) ◽  
pp. 7 ◽  
Author(s):  
Fernanda Tessarolli ◽  
Sara Souza ◽  
Ailton Gomes ◽  
Claudia Mansur
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Gelation Time ◽  
Gel Strength ◽  
Economic Feasibility ◽  
Oil Reservoirs ◽  
Conformance Control ◽  
Gelation Kinetics ◽  
Base Polymer ◽  
Harsh Conditions

Relatively smaller volumes of gelling systems had been used to address conformance problems located near the wellbore in oil reservoirs with harsh temperature and salinity conditions. These gelling systems were formulated with high concentrations of low-molecular-weight acrylamide-based polymers crosslinked with polyethylenimine (PEI). However, for in-depth conformance control, in which large gelant volumes and long gelation times were required, lower-base polymer loadings were necessary to ensure the economic feasibility of the treatment. In this study, a gelling system with high-molecular weight 2-acrylamido-2-methylpropane sulfonic acid (AMPS), N-vinyl-2-pyrrolidone (NVP), acrylamide terpolymer, and PEI, with the addition of bentonite as a filler, was formulated. The influence of the gelant formulation and reservoir conditions on the gelation kinetics and final gel strength of the system was investigated through bottle tests and rheological tests. The addition of clay in the formulation increased the gelation time, thermal stability, and syneresis resistance, and slightly improved the final gel strength. Furthermore, samples prepared with polymer and PEI concentrations below 1 wt %, natural bentonite, and PEI with molecular weight of 70,000 kg/kmol and pH of 11: (i) presented good injectivity and propagation parameters (pseudoplastic behavior and viscosity ~25 mPa·s); (ii) showed suitable gelation times for near wellbore (~5 h) or far wellbore (~21 h) treatments; and (iii) formed strong composite hydrogels (equilibrium complex modulus ~10–20 Pa and Sydansk code G to H) with low syneresis and good long-term stability (~3 to 6 months) under harsh conditions. Therefore, the use of high-molecular-weight base polymer and low-cost clay as active filler seems promising to improve the cost-effectiveness of gelling systems for in-depth conformance treatments under harsh conditions of temperature and salinity/hardness.

A Study on a Copolymer Gelant With High Temperature Resistance for Conformance Control

2017 ◽  
Vol 140 (3) ◽  
Author(s):  
Lei Zhang ◽  
Cheng Jing ◽  
Jing Liu ◽  
Khan Nasir
Keyword(s):  
High Temperature ◽  
Oil Recovery ◽  
Oil Reservoirs ◽  
Conformance Control ◽  
Temperature Resistance ◽  
High Temperature Resistance ◽  
Long Time ◽  
Stable Performance ◽  
Water Cut ◽  
Hydrolyzed Polyacrylamide

Due to the limited temperature resistance, the deep conformance control technology of using the conventional hydrolyzed polyacrylamide (HPAM) gel failed to enhance oil recovery in high-temperature heterogeneous oil reservoirs. Therefore, it is necessary to develop a gelant with high temperature resistance to meet the demands of increasing oil production and decreasing water cut in high-temperature heterogeneous oil reservoirs. In this paper, a copolymer is first synthesized by the method of inverse emulsion polymerization using 2-acrylamide-2-tetradecyl ethyl sulfonic acid (AMC16S), acrylamide (AM), and acrylic acid (AA). The developed copolymer has a highly branching skeleton and can resist temperature up to 100 °C. And then, a gelant with high temperature resistance and good shear resistance can be formed by mixing a certain proportion of the developed copolymer and polyethyleneimine (PEI). After the controllable gelation, a copolymer gel is formed and the formed gel can maintain the stable performance for a long time in the high-temperature environment. Experimental results show that the developed gelant can be applied in the conformance control of high-temperature heterogeneous oil reservoir.

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