WO2009088316A1

WO2009088316A1 - Biocide for liquid media used in production of hydrocarbons and transportation of oil and oil products

Info

Publication number: WO2009088316A1
Application number: PCT/RU2007/000752
Authority: WO
Inventors: Evgeny Borisovich Barmatov; Anatoly Vladimirovich Medvedev; Marina Vyacheslavovna Barmatova
Original assignee: Schlumberger Canada Limited; Services Petroliers Schlumberger; Schlumberger Holdings Limited; Schlumberger Technology B.V.; Prad Research And Development N.V.
Priority date: 2007-12-29
Filing date: 2007-12-29
Publication date: 2009-07-16

Abstract

The invention relates to protection of liquid media from microorganisms, mainly to oil and gas production industry, as well as to the needs of oil product transportation and storage. The biocide can be used for antimicrobial protection of media used in well stimulation methods, preferably, for protection of fracturing fluid or drill mud, for prevention of bacteria-induced corrosion of hardware, and also in process of storage and transportation of fuels and lubricants on base of alkane hydrocarbons.

Description

Biocide for liquid media used in production of hydrocarbons and transportation of oil and oil products.

This invention is related to protection of liquid media from microorganisms, preferably in the oil and gas industry, in the stages of transportation and storage of oil products, and can be used for antimicrobial protection of fluids used in oil production stimulation, more preferably, for protection of a liquid medium used for reservoir fracturing treatment, for antimicrobial protection of drilling mud, for preventing of a formation from microbial pollution, preventing of equipment corrosion, caused by microbial activity, and for the operations of storage and transportation of oil and fuel and lubrication materials produced from saturated hydrocarbons.

One of the basic methods of intensification of hydrocarbons production is the hydraulic fracturing technique which is based on the generation of a high- permeability channel in an oil-bearing formation for transportation of oil and gas from the reservoir into the borehole.

The hydraulic fracturing process implies the generation of a fracture in oil-bearing rock due to injection of a fracturing fluid containing propping particles, under great pressure. Generally, natural polymer solutions, such as guar gum, cellulose derivatives, etc., are used as fracturing fluids. One of the severe problems associated with the hydraulic fracturing process is the fracturing fluid degradation caused by bacteria. The fracturing fluid degradation is accompanied by a considerable reduction in the fracturing fluid viscosity, which results in poor performance of this fracturing fluid, as well as in costly shutdown of the equipment.

Another serious problem actual for operation with oil and oil products is accelerated physical deterioration of main assets of oil industry: wells, pipelines, tanks, pumps and other facilities; this deterioration is caused by corrosion due to biogenic sulfur hydrogen (the result of sulfate-reduction in hydrocarbon fluids).

The third serious problem in operation with oil and oil derivatives is pollution with microorganisms directly in the oil reservoir, as well as during transportation in tanks and petroleum infrastructure. The problem of oil aging in industrial tanks for durable storage is very topical, especially in the strategic- storage facilities. In particularly, deterioration of oil quality was noticed during long-run production in oil deposits with multiple flooding. Very intensive process of biodegradation takes place while water pumping into formation, when the anaerobic conditions are not guaranteed.

Here the concept of biodegradation is conversion of oil at the oil-water interface by microorganisms. The primary targets of bacterial digestion are normal alkanes of middle and light fractions of oil. Sciences identified about 30 genus and 100 species of bacteria, fungi, and molds developing in oil. The hydrocarbon-reducing bacteria can live at high temperature (up to 80 - 90⁰C) and with formation fluids with salinity up to 200 g/1.

These numerous processes are accompanied by increase in oil the fraction of pitch and asphaltenes, sulphide and nitrous compounds, growth in density and viscosity, declined in content of alkanes. This changes the oil property and transforms it into maltha and other asphalt bitumens (asphalts and asphaltetes), that fill the cracks and porous space of the formation. This reduced permeability of the near-wellbore zone and formation near the fracture (due to mudding). Other detrimental impacts of bitumen deposition are malfunction of submersible pumps, clogging of production tubing and transportation pipelines.

These problem scan be handles by using of biocides. Biocide (bactericide) is any substance that kills germs. The common disadvantage of most biocides known in oil industry is high toxicity and detrimental impact on fracturing fluids or oil fluids due to chemical interaction. In particularly, high toxicity of most biocides put serious restrictions for use in countries with high environmental criteria for operations with oil and oil products.

High-molecular salts of polyhexamethyleneguanidine (PHMG) show considerable promise in different arts as biocides (refer to I.I. Vointseva, O.N. Skorokhodova, LV. Kazannov, P.M. Valitsky. Varnish for Biocide Coatings. "Paintwork Materials", 1999, pages 3-12.). PHMG preparations meet many requirements imposed on biocides. They are efficient against different microorganisms, low-toxic to homeotherms, non-volatile, readily soluble in water, odorless, colorless and storage-stable and retain their bactericidal properties when applied.

However, the addition of PHMG salts to the borehole fluid, including fracturing fluids, causes problems because these salts are only soluble in water in lower alcohols, but are insoluble in non-polar organic compounds, which hampers the protection of the underground formation and metal equipment against the bacterial corrosion under borehole conditions.

It is known (RU2147487) that some metal nanoparticles show a remarkable biological (antimicrobial) activity and can be used for environmental and medical purposes. For example, silver nanoparticles are used in filtering devices for the purpose of cleaning drinking water. There is also a known promising method of production of such metal particles.

There is a known method (RU2216543) of bactericide production by interaction between l,3,5-trimethylhexahydro-l,3,5-triazine and chloride- containing wastes resulting from epichlorohydrin production. The disadvantage of this bactericide consists in its high toxicity, which has a negative effect on the working conditions during its production and application. There is a known method (US4778654) of production of a bactericidal corrosion inhibitor by mixing an aniline-containing compound, hydrochloric acid, formaldehyde and water. The disadvantages of this bactericide include high labor expenditures required for its production, and low biocide activity.

There is a known method (RU20116380) of production of a bactericidal corrosion inhibitor by interaction between a fatty acid containing 5 to 16 carbon atoms and amino-paraffin containing 10 to 16 carbon atoms, with subsequent dissolution of this bactericide in an aliphatic alcohol, or in an aromatic solvent, or in their mixture. The disadvantage of this bactericide consists in its low water-solubility, which hampers its practical use.

There exists a method (RU2125539) for water enrichment with silver ions in an electrolytic cell with silver electrodes. The electrolytic cell is equipped with automatic regulator of the current and water flowrate meter. The described device is designed for disinfection and conservation of drink water in water, air, and ground vehicles, in the water supply facilities, swimming pools, and also in production of beverages.

There is known an apparatus (US4680114) for purification of drinking water based on water pumping through a electrolytic cell with metal electrodes; the ions of this metal enrich the water flow. The voltage of 34-36 V is applied to electrodes, and this creates saturation of water with ions of metals, preferably silver and copper in proportion of 97 % of cupper and 3 % of silver. The total concentration of copper ions in the outlet water is in the range from 500 to 800 ppb, and the silver ion concentration is about 10 ppb.

However, previous applications of metal ions were focused on purification of drinking water and for other household needs. For example, silver-copper ionization of water is widely used preparation of water in swimming pools. The application of ion solutions for oil producing or oil refinery industries is unknown, as well as potential efficiency.

The technical problem to be solved by the proposed invention consists in the development of a high-performance biocide.

The technical result pursued by the new biocide is a higher efficiency of its use in oil production industry with a simultaneous decline in toxicity, as well as a conservation agent for oil products in the stages of storage and transportation.

The said technical result is achieved by using of ions and/or clusters of the metal from the secondary subgroup of the first group of the Periodic System (copper, silver, and gold) as a biocide for protection of liquid media in the oil and gas production industry and in the oil refining industry. The ions and/or clusters of said metals can be used individually or in combinations.

Herein, the definition of a cluster is a complex agglomerate of several atoms with the size below 1 nm.

The biocide in the stock is presented in the liquid form, including solutions, emulsions, suspension, varnish or paint.

The biocide in the stock is presented in the solid form, including powder, granules, films, fibers.

The biocide is any composition of corresponding metal/metals that is aqua medium (or other fluid) releases ions and/or clusters with partial or complete dissolving of the biocide material.

The biocide in the stock is a chemical composition of the listed metals, including salts, oxides, peroxides, and bases, dispersed metals in zero-valence state, the alloys of metals and their minerals.

The biocide can take the form of metal nanoparticles. The biocide can be water saturated with ions and/or clusters of metals produced by electrolysis.

The biocide can be a solution of clusters and/or ions of appropriate metals produced by mechanical grinding and by chemical or radiation-chemical reducing of metal ions.

The known method (see above) that produces bactericidal ions of silver through creating electric current through silver electrodes dipped into water. However, the ions of silver produced by this method are not stable enough and have a tendency to aggregation with formation of charged clusters and microparticle of zero-valence silver. For example, in the paper (see B. G Ershov, Metal nanoparticles in aquatic solutions: electronic, optical, and catalytic properties. Rossijskij Khimichekij Zhurnal (Zhurnal Rissijskogo Khimichaskogo Obshchestva im. D.I. Mendeleeva), 2001, Vol. XLV, No. 3, pp.20-30) the formation of different clusters (silver, cobalt, nickel, platinum, palladium) was studied. They were produced under conditions of radiation- chemical reduction of water solutions of metal salts. The radiation-chemical reduction of metal ions occurs in reactions of single-electron transfer:

Ag⁺ + e _aq (or CO₂ ^') → Ag° (or CO₂).

It was found that atoms Ag° can convert in to a family of positive and short-living Ag₂ ⁺, Ag₃ ²⁺, Ag₄ ²⁺, Ag₈ ²⁺, as well as neutral clusters. Without stbilizing additives, the lifetime of clusters is about millisecons, and then a rapid aggeration creates micro- and/or nano-particles of the metal.

The use of stabilizers, e.g., surfactants or polymers prolongs the cluster lifetime. The typical example is so-called "blue silver", that absorbs light in the range 600-800 nm. This is a product of reaction between silver clusters and polyarylate anions (see B. M. Sergeev, L. I. Lopatina, A. N. Prusov, and G. B. Sergeev, Formation of silver clusters by borohydride reduction of AgNO₃ in polyacrylate aqueous solutions, Colloid Journal, 2005, Vol. 67, No. 1, P. 72-78). The accurate composition and structure of these forms is not established. It is assumed that they are mainly the complexes of clusters Ag_m ⁿ⁺ (m ^; n <4) and silver cations Ag⁺ with polyacrylate and they are produced as a result of ordering, and, perhaps, dimerization of Ag₄ ²⁺ particles on the polymer chain.

This invention offers to use a new biocide for the needs of oil production, oil processing industries and to use the compounds of metals, predominately, ions and/or clusters of silver, copper, and gold.

Silver has the strongest bactericidal effect, while copper and gold have a bit lower bactericidal properties. For instance, the diphtheria bacillus dies in three days on a silver strip, in six days on a copper strip and in eight days on a gold strip. The typhoid bacillus dies in 18 hours on silver and copper, and it takes one week on gold.

The antibacterial properties of silver and copper are well known, but silver-containing, copper-containing and gold-containing biocides have not been used in the oil and gas industry until now.

The bactericidal properties of silver and its derivatives have been known for thousands of years. For example, the protective properties of copper were known in ancient Egypt where copper vessels were used for storing clean water.

By now, the antimicrobial properties of silver have had a wide use in medicine and in water treatment devices. Silver is a natural antibiotic capable of destroying more than 650 species of bacteria.

The mechanism of the impact of silver on unicellular bacteria is thought to consist in the reaction between silver ions and the cell membrane of the bacterium, resulting in the termination of oxygen delivery into the cell of the bacterium, asphyxia of the microorganism and its death. Some researchers δ attribute special importance to the physicochemical processes, namely, to oxidation of the bacteria protoplasm and its destruction with oxygen dissolved in water, while silver acts as a catalyst. There are data confirming the development of complexes of nucleic acids and heavy metals, resulting in the disturbance of the DNA stability and, consequently, of the viability of the bacteria.

So, according to the current data, the mechanism of the impact of silver on a microbial cell is as follows: silver ions are sorbed by the cell membrane which performs a protective function. The cell remains viable but some of its functions, such as its division, get disturbed (a so-called bacteriostatic effect). As soon as silver is sorbed on the surface of the microbial cell, it penetrates into the cell, inhibits the respiratory chain enzymes and disturbs the oxidation and oxidative phosphorylation processes, resulting in the death of the cell.

The silver ions, even in very low concentrations, are able to destroy the mechanism of sodium ion permeability through membranes of bacterial cells (A.L. Semeykina, V.P. Skulachev, Submicromolar Ag+ increases Na+ permeability and inhibits the respiration-supported formation of Na+ gradient in Bacillus FTU vesicles, FEBS Letters, 1990, V. 269, N. 1, P. 69-72.). The co-existence of ions of different metals in solution may bring synergism in their biocide activity (Wat. Res. 1996. V. 30, N. 8, P. 1905-1913).

The developed biocide can be used for long-term storage of dry and liquid components applied in the oil and gas industry, and especially for the preparation of fracturing fluids, drilling muds and water-shutoff fluids which are used in case of waterflooding and thermal-steam treatment.

The developed biocide can be used for protection of underground formation against bacterial pollution, for which purpose it is added to the fluids used for reservoir pressure maintenance. The developed biocide can be used for prevention of microbial pollution of operating elements in the surface and subsurface equipment; this is achieved by paining of this biocide coating.

The developed biocide can be used for protection of oil and oil products from microbial pollution on the stages of storage and transportation.

The biocide concentration in the media for protection varies in the range from about 10^"9 mol/1 to about 1 mol/1.

The proposed technical solution will be further considered, using the examples of implementation.

EXAMPLE 1

The efficiency of biocide on the base of silver compounds was tested at the example of a fracturing fluid. The sample of fracturing fluid was prepared, that contains a guar gum (5 g/1), potassium chloride (2 g/1), and the samples of biocide 2-8.

Sample 1. Fracturing fluid without biocide (a reference sample). Sample 2. Fracturing fluid with a market-available biocide on the base of isotiazolyne.

Sample 3. Fracturing fluid with silver nitrate. Sample 4. Fracturing fluid with a fine powder of copper oxide. Sample 5. Fracturing fluid with a mixture of copper acetate (II) (60 wt. %) and gold chloride (III) (40 wt. %).

Sample 6. Fracturing fluid with water-soluble nanoparticles of silver with surfactant stabilization. The average size of nanoparticles (X-ray scattering analysis) is 2.6 nm.

Sample 7. Fracturing fluid with silver in cluster form and stabilized with polyvinylpyrrolidone. This solution absorbs light in the range 620-750 nm. Sample 8. Fracturing fluid, with nanoparticles of silver and copper, deposited on a solid substrate (silica gel). The content of nanoparticles of silver and copper is 3.2 and 6.4 wt. %, correspondingly. By data of transmission electron microscopy, the size of nanoparticles ranges from 5 to 53 run.

The fracturing fluid was intentionally infected with sanitary-standard microorganisms Salmonella holerasuis, Lactobacillus reuterri, Shigella sonnery, Geobacillus (10), E. colli (JM 109), E. colli (lOkt), Pseudomonas aerugenosa (7SE) with the total population of 2x10⁵ colony/ml. These samples were stored at the temperature of 37°C during 3 days. The control parameter of the fracturing fluid was viscosity, measured with a viscosimeter Chandler 3500 by a standard procedure at room temperature.

Table 1 show that the sample 3-8 (with the new biocide) and sample 2 (with market-available biocide on the base of isotiasolyne) demonstrate a high viscosity. This is confirmed also by a good safety of the gel during, at least, seven days. On the contrary, the control sample 1 exhibited decomposition of the gel in few hours of experiment.

EXAMPLE 2

The next example demonstrates efficiency of biocide towards bacteria involved in oil biodegradation. The biocide with water-soluble nanoparticles of silver has been tested. To prevent coagulation, silver nanoparticles were stabilized with polymers. By X-ray data, the average size of nanoparticles was 5.2 nm.

A sample of 1 liter of crude oil (density 0.89 g/cm³) was charged with 1 ml of bactericide solution and 50 ml of bacteria-enriched water (bacteria of genus Burkholderia Acidovorax, Pseudomonas, Bacillus, and Serratia). The liquid semination was 6xlO⁵ colony/ml. The composition was mixed by a magnetic stirrer at the temperature of 28°C for 10 days. After this period, the oil viscosity was tested and the concentration of living bacteria was determined. It was revealed that the oil viscosity remained constant and the medium was absolutely sterile (no living bacteria or spores).

Table 1.

Claims

What we claim:

1. A biocide for protection of liquid media used in hydrocarbon production, for protection of drill mud, oil and oil products while production, handling, and transportation, for protection of subterranean reservoir, for preventing of pollution of a pay zone and eliminating the corrosion of well basic assets due to activity of microorganisms, wherein the ions and/or clusters of the metals of the secondary subgroup of the first group of the Periodic System and the ions and/or clusters of said metals can be used separately or in combinations thereof.

2. The biocide as in claim 1 wherein the stock amount of the biocide is available in liquid form, including solutions, emulsions, suspension, varnish or paint.

3. The biocide as in claim 1 wherein the stock amount of the biocide is available in solid phase, including powders, granules, films, fibers.

4. The biocide as in claim 1 wherein the stock amount of the biocide is a compound of, at least, one of said metals, what can be solved in water or other fluids, partially or completely, with production in liquid media of ions and/or clusters.

5. The biocide as in claim 1 wherein the stock amount of the biocide is a compound of said metals, fine dispersion of metals and their alloys or minerals.

6. The biocide as in claim 1 wherein the stock amount is nanoparticles of said metals.

7. The biocide as in claim 1 wherein the stock amount of biocide is water saturated with ions and/or clusters of metals and produced by electrolysis.

8. The biocide as in claim 1 wherein the stock amount of biocide is a solution of clusters and/or ions of said metals produced by mechanical methods, and also by chemical or radiation-chemical methods by reducing of metal ions.