This study assessed the rate of production of lighter hydrocarbon, pressure build up, isolation and identification of the different species of microorganisms capable of degradating the heavier hydrocarbon in the reservoir. The analysis was performed using a pilot batch reactor set up in the Department of Chemical/Petrochemical Engineering Laboratory, Rivers State University of science and Technology, Port Harcourt. Mathematical model was developed in terms of effect of velocity, depth and porosity on microbial activity in bio-batch reactor and the significant of the functional parameters were examined in this paper. The functional parameters that governance the dynamic characteristics of oil well was examined as well as saturation coefficient, product generation and consumption of substrate. The concentration of the heavier hydrocarbon decreases with increase in the lighter hydrocarbon, water, microbial population and pressure build up in the reservoir. This paper demonstrated the useful of microorganism in improving dead oil well using the necessary conditions that will favour the microbial activities in a reservoir.