Evaluation of Customized Polyacrylamide Based Co-Polymers for EOR Application through Integrated Screening Approach

Abstract

Polymer flooding has been proven to be an effective Enhanced Oil Recovery (EOR) technology in field applications, as it gives rise to better sweep efficiency in the reservoir. For decades, partially Hydrolyzed Polyacrylamide (HPAM) polymer has been commonly used for its viscosifying effects on injected water in both lab and field scale. Nevertheless, the severe degradation and poor conformance control ability under harsh reservoir conditions (high salinity with the presence of divalent ions upto 209,000 mg/l, high pressure and elevated temperature, with significant permeability contrast) hinder the EOR performance. Hence, in recent years, the leading stakeholders have been focusing on novel polymer flooding solutions tackling improved performance under harsh reservoir conditions. Therefore, a suitable compatible polymer is required to achieve successful EOR implementation.

This study developed engineered brines with variations of divalent content combined with low concentrations of a bespoke formulated polyacrylamide-based co-polymer suitable for the harsh conditions encountered in the candidate field. The novel polymer (associative polymer) was evaluated in comparison with the HPAM utilizing a wide range of injection brines. An extensive evaluation of reservoir characterization, including petrophysical property analysis, conventional core analysis (CCA), and fluid-fluid analysis, were conducted. Moreover, formation damage tests were conducted to evaluate the brine's compatibility with the respective formation. After which, several polymer evaluation studies, including polymer screening, rheological tests, and displacement efficiency tests, were also conducted to shortlist the candidate polymers through the core-flooding experiments.

The novelty of this integrated study is confirming that the bespoke co-polymer exhibits a nonmonotonically increasing behavior with shear rate, leads to the improvement in the volumetric sweep efficiency thanks to its shear thickening feature and better compatibility with engineered brine, thus is able to displace more bypassed oil. Results have shown the potential of achieving significantly increased performance, such as giving temporary polymer retention and higher oil displacement efficiency, utilizing the proposed HEOR in the candidate reservoir across the entire encountered range of heterogeneity.

Date of Award	Aug 2023
Original language	American English
Supervisor	Mohamed Haroun (Supervisor)