Determine, through experiments and computer simulation, the best design and evaluation of a combined microbial/surfactant-polymer system for improved oil recovery.
This project was selected as a Historic Black College and Universities non-competitive award.
Prairie View A&M University
Prairie View, TX
Many domestic oil fields are facing abandonment, although they still contain two thirds of their original oil. A significant number of these fields can yield additional oil using AOR techniques. Yet many independent producers do not have the capital to implement costly advanced recovery programs. Marginal wells are desperately in need of inexpensive AOR technologies to extend the life of oil and gas reservoirs with unrecoverable reserves and prevent premature abandonment. Microbial enhanced oil recovery (MEOR) technologies have become established as cost-effective solutions for declining oil production.
The research conducted indicated that the improved recovery efficiency for different nutrients appeared to be related to population numbers and not to different recovery mechanisms. High surfactant production is the main recovery mechanism during the NIPER 1A recovery experiments, while improved sweep efficiency is the main recovery mechanism during the NIPER 11 experiments. These conclusions are supported by low surface tension values during the NIPER 1A experiments and high viscosity during the NIPER 11 experiments. It was concluded that mixed microbial cultures hold more promise than single microbial cultures.
A microbial advanced oil recovery (AOR) technique could cost-effectively increase oil recovery from mature domestic fields.
Among the project highlights:
The emphasis of this work is on the design and evaluation of a combined microbial/surfactant-polymer system for AOR. The surfactant-polymer system will utilize bacteria that are capable of both bio-surfactant and bipolymer production. Change in the microbial feeding nutrients was expected to produce the change from surfactant to biopolymer production. It was found, however, that two separate microorganisms are needed to produce surfactant and polymer.
Laboratory experiments were done using different carbon sources in order to determine if the microorganisms respond differently to different nutrients. Microbial samples grown for two months were transferred to flasks with different carbon sources. Weekly samples were withdrawn and colonies counted. Surface tension and viscosity was measured.
Experiments in multi-layer sandpacks were performed. The different layers were injected with one pore volume of different broths inoculated with the appropriate microorganisms. This injection was done at a low flow rate (1 foot per day). The sandpack was closed for 6 days to allow growth and chemical production (surfactant/polymer). After the shut-in period, the sandpack was opened and waterflooded. The fluids were collected, and the final oil saturation determined from mass balance.
The project is in the final stages of completion.