THE POTENTIAL OF INDIGENOUS BACTERIA TO INCREASE POROSITY-PERMEABILITY OF RESERVOIR ROCK: A PRELIMINARY STUDY

Abstract

Oil content extraction from the rock pores can be very complicated due to the high viscosity
of petroleum oil and low degree of reservoir rock porosity as well as its permeability. A research had been
carried out with the use of mix populations of indigenous bacteria isolated from formation water (fw), wellsite sludge (ws) and well mud (wd). Limestones was used as samples. This cores were soaked for 2 (two)
weeks in 550C, a media contained of 1% molasse dissolved in sterillized formation water and 20% crude oil
as covering. During the research, there was a change in the pH environment from neutral to acid. Acid
production from the reaction result with carbonate in the solution will lower pH of the water that was
produced. Changing value of porosity (%) that was injected by bacteria from fw, ws, and wd, increases
respectively 23.22, 68.29, 14.89, and changing value of permeability (%) respectively 56.28, 137.83, 35.77.
Even though on average there were an increase in value of porosity and permeability, there were also a
decrease in the value of porosity and permeability of a few of the limestones samples. Inoculum bacteria
from the pollution around the oil well are much more adaptive and give more carbonate dissolving reaction
than the other actions. MEOR (microbial enhanced oil recovery) technique is really dependent on the growth
of the microbes in site, and the development of the secondary metabolit products that can change the porosity
and permeability of the reservoir limestones.