Effect of Reservoir Salinity between Bioacid and Carbonate Rock Based on Biometabolic Analysis

Acidic fluids produced
by microbial metabolism, such as organic
acids, can effectively increase the porosity and permeability of carbonate
rocks, thus improving oil recovery. In this experiment, facultative
anaerobic strains utilizing crude oil as the sole carbon source were
screened out. Acid production from crude oil was determined, and their
physiological and biochemical properties and gene expression under
the influence of salinity degree were studied. A core experiment simulation
was performed to explore the effects of the selected microorganisms
on the permeability and porosity of the reservoir. The results showed
that the isolated microorganism was Bacillus licheniformis. Microbial growth was excellent when the salinity was 2 × 104 mg/L. The acid production concentration reached 380 mg/L.
The transcriptome test revealed that compared with the 1 × 104 mg/L salinity degree, 2 × 104 mg/L salinity
changed 106 genes, of which 69 and 37 were up and downregulated, respectively.
The functional annotation of differential genes was performed by GO
enrichment. The differential expression of GO:0015940 and GO:0015939
is a biological cause that affects microbial oil recovery effect.
The expression of these differential genes may be the root cause of
microbial effects. The results of simulated flooding experiments show
that the selected oil-removing bacteria can increase oil recovery
by about 7.3%. This study provides theoretical support for the microbial
enhancement of carbonate recovery from a microscopic perspective.