Patent Publication Number: US-2012034313-A1

Title: Microbiocide/Sulfide Control Blends

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of U.S. Provisional Patent Application No. 61/371,261 filed Aug. 6, 2010, which is incorporated herein in its entirety by reference. 
    
    
     TECHNICAL FIELD 
     The present invention relates to methods and compositions for killing bacteria and/or suppressing the production of hydrogen sulfide, and more particularly relates, in one non-limiting embodiment, to chemical blends that simultaneously kill bacteria and suppress the production of hydrogen sulfide. 
     BACKGROUND 
     Hydrocarbon fluids, such as crude oil, crude oil emulsions, oilfield condensate, petroleum residua and sometimes even refined fuels often contain hydrogen sulfide (H 2 S). H 2 S is often generated downhole and in hydrocarbon-bearing subterranean formations by sulfate-reducing bacteria (SRB) that are naturally present. In the drilling, production, transport, storage, and processing of hydrocarbon stocks, the H 2 S encountered may cause many problems ranging from malodors to metal corrosion. Because of the volatility of H 2 S, which is of low molecular weight, it tends to evolve into vapor spaces, where its offensive odors create problems in and around storage areas and throughout pipelines and shipping systems used for transporting the hydrocarbon. 
     Bacterial contamination of drilling fluids themselves may contribute to a number of problems in the oil field. First, many of the muds contain sugar based polymers in their formulation that provide an effective food source to bacterial populations. This can lead to direct degradation of the mud. In addition, as noted, bacterial metabolism can generate deleterious products, particularly hydrogen sulfide which is not only a toxic gas, but may lead to decomposition of mud polymers, formation of problematic solids, such as iron sulfide, and/or corrosive action on drilling tubes and drilling hardware. 
     Various additives have been employed in efforts to alleviate these problems. Glutaraldehyde and alkyl dimethyl benzyl ammonium chloride are known biocides used for killing bacteria in these environments. Certain quinones are also known to inhibit sulfide production from sulfate-reducing bacteria in the oilfield. 
     Other additives are known to inhibit or remove H 2 S and/or mercaptans after they are formed. For example, oil-soluble quaternary ammonium compounds have been known to scavenge H 2 S and various sulfur compounds, including mercaptans, from certain oils, especially high boiling, heavy residual fuels. Other chemistries and methods for removing H 2 S and mercaptans from hydrocarbons include caustic (NaOH solutions) and cobalt with caustic (Merox™ process of UOP, Merichem processes), as well as hexahydrotriazines. 
     It would be desirable to develop compositions and methods that would simultaneously kill bacteria and suppress the production of hydrogen sulfide in a fluid that is treated, for instance a drilling fluid or crude oil. 
     SUMMARY 
     There is provided, in one non-limiting version, a chemical blend that is a microbiocide and also suppresses hydrogen sulfide when the blend is added to a fluid. The blend includes at least one first chemical, at least one second chemical, and a solvent that includes MEG. The at least one first chemical includes, but is not necessarily limited to, glutaraldehyde, tetrakishydroxymethyl phosphonium sulfate (THPS), a quaternary amine compound, a thiocyanate, a carbamate, a cinnamaldehyde, an alkyl dimethyl benzyl ammonium chloride, and/or a diamine diacetate. The at least one second chemical is a quinone, including but not necessarily limited to 9,10-anthrahydroquinone; 1,4-benzoquinone; and/or 1,8-dihydroxyanthraquinone. A required solvent is monoethylene glycol MEG, or a solvent package including monoethylene glycol. 
     In another non-restrictive embodiment, there is provided a method for simultaneously killing bacteria and suppressing the production of hydrogen sulfide in a fluid which involves adding to the fluid an effective amount of a chemical blend to simultaneously kill bacteria and suppress the production of hydrogen sulfide, where the chemical blend is as described above. 
    
    
     DETAILED DESCRIPTION 
     The inventors have discovered that certain blends of at least a first chemical, at least a second quinone chemical, and a solvent that includes monoethylene glycol give synergistically better results at killing bacteria and/or suppressing the production of hydrogen sulfide as compared with the simple addition of the results of each of the components of the blend used separately or in blends having less than one of the three components. 
     The at least one first chemical may be a glutaraldehyde, a tetrakishydroxymethyl phosphonium sulfate (THPS), a quaternary amine compound, a thiocyanate, a carbamate, a cinnamaldehyde, an alkyl dimethyl benzyl ammonium chloride, a diamine diacetate, and combinations thereof. A suitable diamine diacetate includes, but is not necessarily limited to, cocodiamine diacetate. As previously noted, some of these are known biocides, including glutaraldehyde and alkyl dimethyl benzyl ammonium chloride (also known as ADBAC or benzalkonium chloride). Alkyl dimethyl benzyl ammonium chloride may have the following structure: 
     
       
         
         
             
             
         
       
     
     where n is from 8 to 18. THPS is known for iron sulfide scale removal. 
     The at least one second chemical may be a quinone. Suitable quinones include, but are not necessarily limited to, hydroquinones, benzoquinones, anthraquinones, and mixtures thereof. Suitable, more specific quinones include, but are not necessarily limited to, 9,10-anthrahydroquinone; 1,4-benzoquinone; and/or 1,8-dihydroxyanthraquinone. 
     In a non-limiting embodiment, at least one third chemical may be added to the chemical blend. The third chemical may be a phosphate compound. Suitable phosphate compounds include, but are not necessarily limited to, an ortho-phosphate, an ethoxylated phosphate, monosodium phosphate (NaH 2 PO 4 ), a phosphate ester, a thio-phosphate ester, and mixtures thereof, and/or a scale inhibitor, such as a phosphate ester or phosphate salt. NaH 2 PO 4  is known as a buffer. A suitable scale inhibitor may include, but is not necessarily limited to, AQUARITE ESL available from Rhodia. A suitable phosphate compound includes, but is not necessarily limited to, RHODAFAC PL6 available from Rhodia. 
     These blends are novel and unusual because it was previously thought that the first chemical, and the second chemical could not be combined into a single product without loss of activity or loss of stability. By ‘loss of stability’, it is meant that the components of the blended product would separate over time. Stability is achieved by a required solvent, which may include monoethylene glycol (MEG). The solvent may be a solvent package which includes MEG and may include other relatively low molecular weight alcohols and glycols, defined as those having six carbon atoms or less. 
     The proportions of the various components in the chemical blend may be as shown in the ranges of Table I. One non-limiting proportion range is given in the second column (First Range), whereas an alternative non-restrictive proportion range is given in the third column (Second Range). It will be appreciated that any lower threshold for a chemical may be combined with any upper threshold between the second column and the third column to give further alternative proportion ranges. 
     
       
         
           
               
             
               
                 TABLE I 
               
             
            
               
                   
               
               
                 Proportion Ranges of Chemicals of Components 
               
               
                 for the Blends, Vol % 
               
            
           
           
               
               
               
            
               
                 Component 
                 First Ranges 
                 Second Ranges 
               
               
                   
               
            
           
           
               
            
               
                 FIRST CHEMICAL 
               
            
           
           
               
               
               
            
               
                 glutaraldehyde 
                 about 10 to about 70, 
                 about 20 to about 35, 
               
               
                   
                 alternatively 
                 alternatively 
               
               
                   
                 about 10 to about 40 
                 about 10 to about 20 
               
               
                 THPS 
                 about 10 to about 70 
                 about 20 to about 35 
               
               
                 quaternary amine 
                 about 10 to about 70 
                 about 20 to about 35 
               
               
                 compound 
               
               
                 thiocyanate 
                 about 10 to about 70 
                 about 20 to about 35 
               
               
                 carbamate 
                 about 10 to about 70 
                 about 20 to about 35 
               
               
                 cinnamaldehyde 
                 about 10 to about 70 
                 about 20 to about 35 
               
               
                 alkyl dimethyl benzyl 
                 about 10 to about 70 
                 about 20 to about 35, 
               
               
                 ammonium chloride 
                 alternatively 
                 alternatively 
               
               
                   
                 about 10 to about 40 
                 about 10 to about 20 
               
               
                 diamine diacetate 
                 about 10 to about 70 
                 about 20 to about 35 
               
            
           
           
               
            
               
                 SECOND CHEMICAL 
               
            
           
           
               
               
               
            
               
                 Quinone 
                 about 0.1 to about 10 
                 about 0.1 to about 5 
               
            
           
           
               
            
               
                 Required SOLVENT 
               
            
           
           
               
               
               
            
               
                 MEG 
                 about 20 to about 80 
                 about 40 to about 75 
               
            
           
           
               
            
               
                 THIRD CHEMICAL 
               
            
           
           
               
               
               
            
               
                 NaH 2 PO 4   
                 about 0.1 to about 80 
                 about 5 to about 60, 
               
               
                   
                   
                 alternatively about 5 
               
               
                   
                   
                 to about 40 
               
               
                 ortho-phosphate 
                 about 1 to about 25 
                 about 1 to about 10 
               
               
                 ethoxylated 
                 about 1 to about 25 
                 about 1 to about 10 
               
               
                 phosphate 
               
               
                 scale inhibitor 
                 about 0.1 to about 20 
                 about 0.1 to about 7.5 
               
               
                 phosphate ester 
                 about 1 to about 25 
                 about 1 to about 10 
               
               
                 thio-phosphate ester 
                 from about 1 to about 25 
                 about 1 to about 10 
               
               
                   
               
            
           
         
       
     
     Any combination using a first chemical, a second chemical, and a solvent may be used to practice this invention. However, particularly suitable combinations of first chemicals with second chemicals are expected to be the following: 
     a. glutaraldehyde,
         NaH 2 PO 4 , and   a quinone selected from the group consisting of 9,10-anthrahydroquinone; 1,8-dihydroxyanthraquinone; 1,4-benzoquinone; and mixtures thereof, and   a solvent comprising MEG.       

     b. THPS,
         NaH 2 PO 4 , and   a quinone selected from the group consisting of 9,10-anthrahydroquinone; 1,8-dihydroxyanthraquinone; 1,4-benzoquinone; and mixtures thereof, and   a solvent comprising MEG.       

     c. a quaternary amine compound,
         a quinone selected from the group consisting of 9,10-anthrahydroquinone; 1,8-dihydroxyanthraquinone; 1,4-benzoquinone; and mixtures thereof,   an ortho-phosphate, and   a solvent comprising MEG.       

     d. alkyl dimethyl benzyl ammonium chloride,
         a quinone selected from the group consisting of 9,10-anthrahydroquinone; 1,8-dihydroxyanthraquinone; 1,4-benzoquinone; and mixtures thereof, and   a solvent comprising MEG.       

     e. a diamine diacetate,
         a quinone selected from the group consisting of 9,10-anthrahydroquinone; 1,8-dihydroxyanthraquinone; 1,4-benzoquinone; and mixtures thereof, and   a solvent comprising MEG.       

     f. a thiocyanate,
         a quinone selected from the group consisting of 9,10-anthrahydroquinone; 1,8-dihydroxyanthraquinone; 1,4-benzoquinone; and mixtures thereof;   an ethoxylated phosphate; and   a solvent comprising MEG.       

     g. THPS,
         a scale inhibitor,   NaH 2 PO 4 , and   a quinone selected from the group consisting of 9,10-anthrahydroquinone; 1,8-dihydroxyanthraquinone; 1,4-benzoquinone; and mixtures thereof, and   a solvent comprising MEG.       

     h. THPS, NaH 2 PO 4 , and
         a quinone selected from the group consisting of 9,10-anthrahydroquinone; 1,8-dihydroxyanthraquinone; 1,4-benzoquinone; and mixtures thereof, and   a solvent comprising MEG.       

     i. THPS,
         a phosphate ester, and   a quinone selected from the group consisting of 9,10-anthrahydroquinone; 1,8-dihydroxyanthraquinone; 1,4-benzoquinone; and mixtures thereof, and   a solvent comprising MEG.       

     j. THPS,
         a scale inhibitor,   a phosphate ester, and   a quinone selected from the group consisting of 9,10-anthrahydroquinone; 1,8-dihydroxyanthraquinone; 1,4-benzoquinone; and mixtures thereof, and   a solvent comprising MEG.       

     k. cinnamaldehyde,
         a quinone selected from the group consisting of 9,10-anthrahydroquinone; 1,8-dihydroxyanthraquinone; 1,4-benzoquinone; and mixtures thereof, and   a solvent comprising MEG.       

     In practicing the method using these chemical blends, an effective amount of a chemical blend to simultaneously kill bacteria and suppress the production of hydrogen sulfide will be added to the fluid. The exact amount of the chemical blend or range of effective amounts will be difficult to determine in advance and may require empirical methods to determine an optimal range or amount. For instance, an optimum range or amount may be affected by one or more factors including, but not necessarily limited to, the amount and type(s) of sulfate-reducing bacteria in the fluid, the temperature and pressure of the fluid, the chemical composition of the fluid and combinations of these effects. However, to give an idea of one representative effective proportion range, the chemical blend may be added to the fluid in an amount ranging from about 5 ppm to about 2000 ppm, alternatively from about 25 ppm to about 1000 ppm. 
     The fluids that may be treated with the chemical blends may be aqueous fluids, hydrocarbon fluids and combinations thereof, whether in a liquid state, gaseous state, or a combination thereof. Suitable fluids include, but are not necessarily limited to, crude oil, natural gas, condensate, oil-in-water emulsions, water-in-oil emulsions, drilling fluids, drill-in fluids, completion fluids, and the like. 
     It will be appreciated that it is not necessary for the chemical blend to kill all bacteria and/or completely suppress the production of H 2 S for the methods described herein to be considered successful or effective, although such excellent results are desired and encompassed herein. The methods are considered successful and/or effective if more bacteria is killed and/or more H 2 S production is suppressed, inhibited or controlled than would occur in the absence of the chemical blend. 
     It is expected that many of the chemical blends described herein will have synergistic efficacy at simultaneously killing bacteria and/or suppressing the production of H 2 S as compared with simply the additive results of using the components of the blends used separately. 
     In the foregoing specification, the invention has been described with reference to specific embodiments thereof, and it is expected to be effective in simultaneously killing bacteria and suppressing the production of H 2 S, as non-limiting examples. However, it will be evident that various modifications and changes can be made thereto without departing from the broader spirit or scope of the invention as set forth in the appended claims. 
     Accordingly, the specification is to be regarded in an illustrative rather than a restrictive sense. For example, specific first, second, and third chemicals, other than those specifically exemplified or mentioned, and/or in different proportions, falling within the claimed parameters, but not specifically identified or tried in a particular application to kill bacteria and/or suppress the production of H 2 S, are within the scope of this invention. The terms “first chemical”, “second chemical”, and “third chemical” are used herein for the purpose of simplifying the categories of chemicals that may be added to the chemical blend and are not intended to limit the order by which the chemicals may be added to the chemical blend. The arrangement as listed within each combination is also not intended to limit the order by which the chemicals may be added to the chemical blend. More than one chemical may be used from the first chemical group and/or from the second chemical group. The third chemical is not necessary to practice the invention, but may be added to the chemical blend to enhance the efficacy of the chemical blend for killing and/or suppressing the production of H 2 S. Similarly, it is expected that the inventive compositions will find utility in killing bacteria and/or for suppressing the production of H 2 S for other fluids besides crude oil. 
     The terms “comprises” and “comprising” in the claims should be interpreted to mean including, but not limited to, the recited elements. 
     The present invention may suitably comprise, consist or consist essentially of the elements disclosed and may be practiced in the absence of an element not disclosed. For instance, a chemical blend may consist of or consist essentially of at least one first chemical, at least one second, quinone chemical, at least one third, phosphate chemical and optionally a solvent, as defined in the claims. Similarly, methods for simultaneously killing bacteria and suppressing production of H 2 S may use a chemical blend that consists of or consists essentially of at least one first chemical, at least one second chemical that is a quinone, and a solvent, as defined in the claims.