Publications

Most of the Indonesian producing oil fields have already reached a very mature development phase characterized by a general production decline. As result of the decline, Indonesia has been a net oil importer since 2003 and in 2008 finally withdrew from OPEC. It is believed that these mature fields still have additional potential that cannot be recovered through the implementation of “traditional development techniques. Nowadays Enhanced Oil Recovery (EOR) has been developed worldwide to access the traditionally untapped resources. The Microbial Enhanced Oil Recovery (MEOR) represents one of these innovative recovery techniques. Previous laboratory research has revealed that the bacteria in a pressurized oil environment produce biosurfactants and gas having the effect of reducing oil viscosity and Interfacial tension (IFT). If oil viscosity and IFT decrease then oil can flow to the surface easily. This study focused on the final laboratory work before a field application. The study demonstrates the ability of bacteria to live in extreme conditions such as high pressure, and then illustrates the core flooding experiment, which investigates the bacterial activities inside cores and finally describes the bacterial impact on the environment and oil pipeline. The high-pressure screening was conducted inside stainless steel conditioning cells and oxygen inside the cells was replaced by nitrogen. The bacterial flooding was conducted using the slim tube apparatus. The experiments revealed that two bacteria used in this experiment, Bacillus polymixa and Bacillus sp., can live in pressure of up to 500 psi. In the core flooding experiment, four different core samples were used. Two core samples were used as control without bacterial injection (coded as core A and C), while bacteria were injected into the others two (coded as core B and D). After bacterial injection, core B was soaked inside brine water for one week while core D was soaked for four weeks. As the result oil recovery improvement on core B was equal to 14.84%, and on core D was 10.79%. It is believed that the improvement on core A was better in comparison to core D because the initial petrophysical parameters in core A were higher (core A: permeability was 39.01 mD and porosity was 24%, core D: permeability was 29 mD and porosity was 18%). The bacteria also changed the core B permeability by 3.53% and core D by 57.92% and also changed core B porosity by 4.0% and core D by 11.11%. The bacteria are environmentally friendly as they produce only methane gas and therefore do not corrode the oil pipeline. These experiments show that these bacteria have the potential for field applications.