Controlling the Hydro-Swelling of Smectite Clay Minerals by Fe(III) Reducing Bacteria for Enhanced Oil Recovery from Low-Permeability Reservoirs

Abstract

The hydro-swelling of smectite clay minerals in low-permeability reservoirs further decreases the reservoir permeability and results in low oil recovery. Currently, the traditional chemical anti-swelling agents are widely used, but most of them are only effective in the short term and are not environmentally friendly. Here, we report the use of Fe(III) reducing microorganisms (FeRM) as a novel green anti-swelling agent to enhance oil recovery from low-permeability reservoirs. The results showed that FeRM (Proteus hauserifective) inhibited/reduced the hydro-swelling of smectite clay minerals through a three-step biochemical mineralization reaction process. The structural Fe(III) reduction in minerals by FeRM can be an important driving force for illitization. The maximum inhibition efficiency (36.6%) and shrinkage efficiency (69.3%) were achieved at 35 °C and 0.1 Mpa. Furthermore, core displacement tests showed that FeRM reduced the waterflooding injection pressure by 61.1%, increased the core permeability by 49.6%, and increased the oil recovery by 8.1%. Finally, the mechanism of FeRM-enhanced oil recovery was revealed. This study demonstrates that using FeRM to inhibit/reduce the hydro-swelling of clay minerals holds great potential to enhance the oil recovery from low-permeability reservoirs.

Response Characteristics of the Community Structure and Metabolic Genes of Oil-Recovery Bacteria after Targeted Activation of Petroleum Hydrocarbon-Degrading Bacteria in Low-Permeability Oil Reservoirs

“…During the process of MEOR, indigenous activation microbial enhanced oil recovery technology has been recognized to have the advantages of strong adaptability, good compatibility with the reservoir, and low cost. , In this process, crude oil is degraded by synergistic effects of microbes and metabolites, leading to improved swept volume and enhanced oil recovery. − Various mechanisms for enhancing oil recovery, such as viscosity reduction, improved fluidity, and increased oil displacement, have been summarized in numerous previous research reports on MEOR processes. − However, a slight drawback is that these mechanisms only broadly elucidate the enhanced oil recovery process of oil-producing functional microorganisms in reservoir environments from a macroscopic perspective. They did not reveal from a microscopic perspective how the enhanced oil-recovery genes of these functional microorganisms are expressed due to changes in microbial community structure and how the corresponding metabolic pathways are affected.…”