This is the first article in a series reviewing 2014 patents focused on Enhanced Oil Recovery (EOR). The initial article relates to the technology area of Microbial Enhanced Oil Recovery (MEOR), which concerns the use of microbes to extract oil from oil-containing formations.

Although only five MEOR-related patents issued in 2014, patent activity generally in the EOR area was robust, with 50+ patents having issued. In the upcoming articles, these remaining patents will be similarly reviewed according to their particular subject matter. While this article covers patents in MEOR, which is a biological method of oil recovery, other recovery methods such as chemicals: polymer flooding, chemical flooding, liquid carbon dioxide flooding, and hydrocarbon displacement; physical methods: thermal recovery, steam flooding, gas drive oil; and technical methods: hydraulic fracturing, hydraulic jet drilling, etc. will be covered in upcoming articles to the extent patents in these areas have issued.

The development of MEOR processes accompanies a renaissance in U.S. oil and gas production that has vaulted the U.S. into the number one position in gas production, with the same expectation for oil production in the next few years. This is a remarkable achievement when one considers that it is has been accomplished primarily through the use of wells on privately-owned lands. Vast additional reserves are held in government-owned lands. The expansion in production has been enabled by advances in drilling techniques, processes, equipment and materials, and such advances represent value to the companies who have developed them. Companies often attempt to protect this type of valuable intellectual property through patents. In this article and the next several to follow, 2014 patents related to enhanced oil recovery (EOR) will be summarized.

MEOR generally involves injecting microbes and nutrients into a well followed by closure of the well for a period of time to allow the microbes to do their work. The microbes are designed to produce various gases, organic acids, solvents, polymers and surfactants. Typical microbes includeBacillusClostridiumPseudomonasEurobacteriumFusobacteriumBacteroidesLeuconostoc mesenteroidesDesulfovibrioMycobacterium, and Peptococcus. Typical nutrients include materials such as molasses, corn syrup, and sucrose. MEOR increases well production in a number of ways. The production of gas and biomass by the microbes displaces oil, pushing it toward the surface. The surfactants and polymers lower the surface interfacial tension between the oil and the rock/water surface, which causes emulsification and a more comprehensive oil/water split. The solvent, acids and surfactants remove heavy long chain hydrocarbons from the pores of the formation to enhance permeability.

Review of patents in the MEOR area indicates that substantial research efforts are ongoing, at least of the type for which patent protection is sought. Moreover, the area of research within MEOR appears to be broad-based. One of the patents, (U.S. 8,753,865), is directed to particular types of microbe systems. Two of the patents relate to the microbe-containing injection fluid (U.S. 8,826,975 and U.S. 8,889,601). One patent, (U.S. 8,746,334), relates to an MEOR process for wells that have undergone a CHOPS process, and a final patent, (U.S. 8,783,345), relates to a process of delivering oxygen to the microbes in the well bore. In view of the relatively low cost of components for the MEOR process (microbes and nutrients), and the environmentally friendly aspect of the technology, research is likely to continue.

MEOR patents are summarized below. Attached Table 1 lists relevant information on the MEOR patents reviewed. Table 2 contains a representative independent claim from each.

Microbials

U.S. Patent No. 8,746,334 generally relates to an MEOR treatment of wells having completed primary CHOPS production. CHOPS stands for Cold Heavy Oil Production with Sand. This method is a non-thermal recovery method utilizing a progressing cavity pump which pulls to the surface a mixture of oil, water and sand. The production of sand from the oil reservoirs in this manner results in pathways of high permeability, known as wormholes. The patent covers selecting a well in communication with a reservoir having at least one wormhole, and determining whether sufficient gas-producing microbes are present to re-pressure a drainage portion of the well. If there isn’t a sufficient amount of microbes, an injectant is prepared containing gas-producing microbes, nutrients and a fluid base. If there is sufficient microbes, then an injectant is prepared containing only the nutrient and fluid base. The injectant is then injected into the wormhole and the well is shut until the well pressure reaches a target point.

U.S. Patent No. 8,753,865 generally relates to a microbe system for enhanced oil recovery or in situ bioremediation. The system contains microbes from three different classes: at least one species of the genus Thauera having a 16S rDNA nucleic acid molecule that has at least 95% identity to SEQ ID NO:15; at least one species having a 16S rDNA nucleic acid molecule that has at least 95% identity to SEQ ID NO: 16; and at least one species having a 16S rDNA nucleic acid molecule that has at least 95% identity to SEQ ID NO: 17, where the Thauera species is at least 60% of the system.

U.S. Patent No. 8,783,345 generally relates to an MEOR process where the microbes consume oxygen. Water is stored and delivered to a wellbore. The water is injected into the oil formation with a tubing string in the well bore. Oxygen is introduced into the oil-bearing formation for consumption by the microbes.   The oxygen is delivered in a gas phase in such a way that it does not contact the wall of the tubing string or the water when it is within the tubing string. The method is intended to avoid corrosion of metallic equipment processing the water and precipitation and scaling in the water resulting from the oxygen.

Click here to view image.

U.S. Patent No. 8,826,975 generally relates to an MEOR process where the water used for injection into an oil-bearing formation is treated. Specifications including biochemical oxygen demand (BOD) and total organic carbon (TOC) are established for the water to be introduced into the oil bearing formation. Microbes are then injected into the oil formation. The water is treated outside of the oil formation prior to injection to reduce their BOD and TOC so as to meet the specifications, in order to facilitate the microbial growth. The water is next injected into the oil formation. Finally, oxygen is introduced into the oil bearing formation for consumption by the microbes.

Click here to view image.

U.S. Patent No. 8,889,601 generally relates to an injection site formulation for use in an oil well containing an inhibited nutrient composition. The inhibited nutrient composition contains at least one nutrient at concentrations greater than 10% w/v, which are sufficient to inhibit microbial growth during transit to a target well site. At the target well site the nutrients activate and enhance the microbial population.

Table 1

EOR Patents — MEOR

Click here to view table.

Table 2

Enhanced Oil Recovery — MEOR

Click here to view table.