This paper depicts the laboratory results as well as the well production performances of five oil wells that were treated with microbial technology using ‘huff & puff’ method. It is the second microbial stimulation project in Bokor field after the pilot project implemented in July 20001 .

However, in this project the wells selected for the treatment were not very much depleted as compared to the three pilot wells, which were very much depleted in their production.

Several types of laboratory analyses conducted on the crude oil samples showed encouraging results in favour of this technology whereby there is an improvement in crude oil flow characteristic. This is due to the degradation of heavy molecular weight into lighter hydrocarbons upon reaction with the microbes. Crude oil rheological study conducted on post-treatment samples concluded an enhancement in crude oil mobility in a majority of the wells treated. A reduction in the emulsion stability of the crude was also observed after treatment.

Post treatment production performance monitoring for all the five wells have shown positive response to treatment with better oil gained per well. Collectively, the five wells produced an average of 111 bopd per well of incremental oil, compared to 90 bopd per well incremental in the pilot project over five months post treatment monitoring period. Nonetheless, these favourable results were largely overshadowed by the high variability between good responding wells and the poor responding wells. Detail explanations to describe the well responses due to treatment were provided based on laboratory analyses results and well production performances.

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