Maximizing Oil Recovery Through Hybrid Smartwater Surface Active Polymer: A Novel Environomic EOR Technology
Authors: Haroun Mohamed , Rahman Md Motiur , Li Yao , Jiang Chengyang , Ghedan Shawket , De Bakker Joost , Wu Yongfu 
Published: October 2019

This study aims to develop a novel technology using in-house surface-active polymer (SAP) developed for enhanced oil recovery (EOR) by improving in-situ conformance controlling via self-adaptive viscofication and surface wettability. This study combines the preconditioning capability of smart water and the volumetric sweep efficiency improvement of polymer flooding. The success of this study could lead to an advanced EOR process, applicable specifically under complex reservoir field conditions.

For decades, numerous studies have been attempted to address recovery issues through a single EOR technique. Among these studies, smart water flooding (SWF) has demonstrated potential in increasing oil recovery through wettability alteration, especially for complex reservoir conditions, such as reservoirs with high clay content and high heterogeneity. The key innovation of this investigation is to incorporate cost-effective, surface active polymeric system with SWF to further improve oil recovery efficiency. As opposed to regular polymers and fluid diverting agents, such a surface-active polymeric system with a distinct behavior termed as "Self-Adaptive Thickening" can increase the aqueous phase viscosity at high shear rate thereby lowering the water-oil mobility ratio. It can also selectively seal-off (long term or temporary) a thief layer or a channel to divert water to relatively low-permeability oil-rich zones. SWF works in tandem with the surface-active polymeric system to reduce the residual oil saturation by altering reservoir wettability, therefore increasing the displacement efficiency of the process.

Multiple engineered brines were analyzed, prepared, and selected as preconditioning fluids. The tested coreplugs were flooded with the selected engineered brines combined with the different types of polymers to establish impact on recovery. This involved screening and short-listing multiple combinations of Hybrid SWF SAP (HSWFSAP) samples. These shortlisted formulations were further tested under reservoir pressure, temperature, oil saturation and wettability conditions. Coreplugs were saturated with synthetic formation water, which was further reduced to initial water saturation and aged with crude oil. The plugs were flooded with varying preconditioning slugs combined with tested polymeric formulations.

This study provides an improved depiction of the interdependency of the key parameters and their associated response on displacement efficiency, which allows for a better understanding of SAP performance. The task concludes with an optimization study of the polymer selection criteria from development to design protocol.

In summary, a novel in-house SAP tailor made to fit the unique characteristics of candidate reservoirs was developed and tested for comparison with regular HPAM. This increased displacement efficiency (D.E), via simultaneous in-situ wettability alternation and sweep efficiency improvement, while minimizing the water and EOR fluid consumption. Development and implementation of such technologies can bring a new era of sustainable smart EOR for the region.