# Research on the Mechanism and Characteristics of Gel–Microbial Composite Oil Displacement in Hypertonic Heavy Oil Reservoirs

## TL;DR

A new gel-microbial system is developed to improve oil recovery in heavy oil reservoirs by combining plugging and microbial oil displacement methods.

## Contribution

A novel composite system integrating a biocompatible gel with Bacillus licheniformis and surfactant is introduced for enhanced oil recovery.

## Key findings

- The ICRG gel increases displacement pressure fourfold by plugging high-permeability zones.
- ZY-1 strain reduces oil-water interfacial tension by 61.9% and crude oil viscosity by 65%.
- The composite system achieves 15% and 20% oil recovery in one- and two-dimensional models, respectively.

## Abstract

To address the limitations of traditional chemical flooding—such as high cost, environmental impact, and formation damage—and the challenges of standalone microbial flooding—including preferential channeling, microbial loss, and limited sweep efficiency—this study develops a novel composite system for a high-permeability heavy oil reservoir. The system integrates a 3% scleroglucan + 1% phenolic resin gel (ICRG) with Bacillus licheniformis (ZY-1) and a surfactant. Core flooding and two-dimensional physical simulation experiments reveal a synergistic mechanism: The robust and biocompatible ICRG gel effectively plugs dominant flow paths, increasing displacement pressure fourfold to divert subsequent fluids. The injected strain ZY-1 then metabolizes hydrocarbons, producing biosurfactants that reduce oil–water interfacial tension by 61.9% and crude oil viscosity by 65%, thereby enhancing oil mobility. This combined approach of conformance control and enhanced oil displacement resulted in a significant increase in ultimate oil recovery, achieving 15% and 20% in one-dimensional and two-dimensional models, respectively, demonstrating its substantial potential for improving heavy oil production.