Laboratory investigation of parameters affecting optimization of microbial flooding in carbonate reservoirs

In the laboratory, bacteria have been shown to produce chemicals such as surfactants, acids, solvents, polymers, and gases mainly CO₂ (Sude, 1992; Herd, 1992; Yijiang et al., 1999; Deng et al., 1999; Zekri et al., 1999) that can significantly contribute to improving displacement and sweep efficiency. Some of these microorganisms can withstand the harsh environment of the oil field and grow at a substantial rate feeding on the organic matter and crude oil itself, thus leading to improvement of oil recovery. Moreover, MEOR process is friendly to the environment. Several field trials have been reported that showed the potential of bacterial enhanced oil recovery (BEOR) in improving oil recovery. Up to date, several investigators have studied the possibility of using microorganism in improving oil recovery, but little work has been reported regarding optimization of the process. As these microorganisms are living organism and it is difficult to predict their behaviour, therefore no attempt has been made to study the parameters that control the process performance. The main objective of this project is to investigate the field parameters that affect the Design of a new process of Microbial Enhanced Oil Recovery in order to achieve optimum oil recovery. In order to reach this goal we must define the factors and field conditions that affect the recovery efficiency of the process and their values that optimize the process. The field parameters considered the most relevant and chosen for this study are the injected bacteria concentration, adaptation time, optimum slug size of bacteria solution, and process application time. The capability of the microbes to transmit through a heterogeneous system and in long cores was also investigated.