In-situ microbial oxygen generation and hydrocarbon conversion in a hydrocarbon containing formation

Abstract

A method for in-situ microbial oxygen generation in an underground hydrocarbon containing formation comprises: injecting into the formation an oxygen generating composition comprising thermophilic chlorate reducing micro-organisms, such as bacteria of the genus Archaeoglobus, Geobacillus and / or Thermus, which multiply at a temperature of at least 60° C.; and inducing the multiplied micro-organisms to convert the hydrocarbons and / or other pore fluid components in-situ into transportable or disposable products

Description

BACKGROUND OF THE INVENTION[0001]The invention relates to a method for in-situ oxygen generation in a hydrocarbon containing formation.[0002]Such a method is known from U.S. Pat. No. 5,163,510.The method known from this prior art reference comprises:[0003]injecting into the formation a fluid comprising a source of oxygen that chemically releases oxygen into the formation;[0004]inducing micro-organisms present in the formation to multiply using the oil as their carbon source and the chemically produced oxygen in the injection water as their oxygen source; and[0005]allowing the multiplied micro-organisms to convert oil from the environment.[0006]In this known method the source of oxygen is provided by injecting water comprising an oxidizing compound selected from the group consisting of H2O2, NaClO3, KClO4, NaNO3 and combinations thereof, which are assumed to be chemically converted to result in oxygen. This assumption is based on the fact that oxygen generation from Microbial Chlorat...

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Benefits of technology

[0033]The method according to the invention may be used to improve bioavailability and biodegradability of hydrocarbons at thermophilic (60-120° C.) & anaerobic conditions in underground formations containing hydrocarbons, volatile fatty acids and other pore fluid components and micro-organisms, by the process of Thermophilic Microbial Chlorate Reduction. The process will generate oxygen in-situ that will enhance bioavailability and biodegradability, which subsequently will enables enhanced recovery of hydrocarbons (of improved quality) via other process like Microbial Enhanced Oil Recovery (MEOR), Microbial Enhanced Coalbed Methane (MECBM) or pretreatment of heavy hydrocarbon crudes (heavy oil, bitumen) prior to processes as Steam Assisted Gravity Drainage (SAGD).

[0041]The thermophilic microbial chlorate-reducing and oxygen-releasing method according to the invention enhances bioavailability and biodegradability of hydrocarbons, which subsequently enables enhanced recovery of upgraded hydrocarbons from hydrocarbon containing formations optionally by:a) enhanced oil recovery from oil bearing formations (MEOR),b) enhanced methane production of coal reservoirs (ECBM),c) pretreatment of heavy oil deposits before SAGD operation; andd) in-situ conversion of oil and natural gas contaminants; H2S, thiophenes and mercaptanes, which conversion involves decontamination of hydrocarbons and is therefore different from US patent 2004 / 0014196A1, which aims to bioremediate hydrocarbons in a shallow low temperature environment or U.S. Pat. No. 5,163,510, which aims to stimulate MEOR only.

[0042]The method according to the invention generates oxygen in-situ that will enhance bioavailability and biodegradability, which subsequently will enable enhanced recovery of hydrocarbons (of improved quality) via other process like Microbial Enhanced Oil Recovery (MEOR), Microbial Enhanced Coalbed Methane (MECBM) or pretreatment of heavy hydrocarbon crudes (heavy oil, bitumen) prior to processes as Steam Assisted Gravity Drainage (SAGD). The process can also enable in-situ natural gas contaminant removal resulting in upgraded hydrocarbons. The invention should therefore be considered as a strong enabling process for other subsurface thermophilic microbial processes.

Problems solved by technology

Utilization of microbes to enhance hydrocarbon recovery is hampered by the limited bioavailability and biodegradability of the hydrocarbons under hot reservoir conditions.

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