Two-step process for microbial enhanced oil recovery
The subject invention relates to methods for post-primary oil recovery that utilize multiple mechanisms of action, wherein biochemical-producing microbes are injected into an oil well in a certain predetermined order, based on, for example, the metabolites and by-products they are capable of producing. Preferably, gas-, acid- and/or solvent-producing microbe such as a Clostridium bacterium, is injected into the well first, followed by a biosurfactant and/or biopolymer-producing microbe, such as Bacillus subtilis, Bacillus licheniformis and/or a combination thereof.
1. A method for enhanced oil recovery from an oil-bearing formation, said method comprising:
A) injecting a first microbe-based product into an oil well; followed by
B) injecting a second microbe-based product and a third microbe-based product into the oil well,
wherein the first microbe-based product comprises one or more microorganisms selected from the group consisting of Clostridium butyricum, Clostridium tyrobutyricum, Clostridium acetobutyricum, Clostridium NIPER 7, and growth by-products thereof selected from the group consisting of butyric acid and acetic acid;
wherein the second microbe-based product comprises a surfactin over-producing strain of Bacillus subtilis and/or growth by-products thereof; and
wherein the third microbe-based product comprises Bacillus licheniformis and/or growth by-products thereof, wherein the growth by-products are selected from the group consisting of levan and lichenysin.
2. The method of claim 1 , wherein the microorganisms of the first, second and third microbe-based products are injected into the oil well in spore form.
3. The method of claim 1 , wherein the microorganisms of the first microbe-based product produce carbon dioxide gas.
4. The method of claim 1 , wherein A) further comprises adding an aqueous solution of one or more proteolytic enzymes to the first microbe-based product at a concentration of at least 1 g/L of the first microbe-based product.
5. The method of claim 1 , wherein A) further comprises injecting water or filtered brine into the oil well after injection of the first microbe-based product.
6. The method of claim 1 , wherein B) comprises injecting the second and third microbe-based products into the oil well simultaneously.
7. The method of claim 1 , wherein B) comprises injecting the second microbe-based product prior to injecting the third microbe-based product.
8. The method of claim 1 , wherein A) and/or B) further comprise injecting nutrients for microbial growth and/or germination enhancers.
9. The method of claim 1 , wherein B) occurs 24 hours or less after A).
10. The method of claim 1 , further comprising the step of shutting the oil well for about 1 week to about 2 weeks after B).
11. The method of claim 1 , used for improved selecting plugging in the oil well.