Prospects of Microbial Enhanced Oil Recovery  in Danish chalk rocks

 

Microbial Enhanced Oil Recovery (MEOR) uses bacteria, producing gas (CO2), polymers or surfactants to help recover residual oil after the water injection depletes its possibilities.

Two strains of Clostridia tyrobutiricum were investigated as possible candidates for MEOR  implementation in Danish chalk reservoir rocks.

Parameters such as high salinity, low permeability, high temperature and toxic elements, being typical characteristics of Danish fields can cause limiting effects on MEOR applications.

The work fulfilled showed that microbes can be adapted to higher salinities through a serial adaptation processes and our experimental microbes are able to survive, regenerate and produce gas and by-products in  salinities of up to 20 g/l higher than salinities in which pure cultures can survive.

Titrimetric method proposed to determine the percentage of CO2 in the total gas produced showed that 67 % of gas was produced in the presence of chalk in microbial solution and just 20% in the process of microbial fermentation with molasses (without chalk).

The microbial solution improved the permeability of three chalk samples by 8.1%, 16.4% and 2658% respectively during 14 days of exposure having formed a big hole in the core sample in the latter case.