REDUCING SUGAR-BASED SULFIDE SCAVENGERS AND METHODS OF USE IN SUBTERRANEAN OPERATIONS
Improved methods and additives for eliminating or reducing concentrations of hydrogen sulfide or soluble sulfide ions for use in subterranean formations and fluids are provided. In one embodiment, the methods comprise: providing a treatment fluid comprising a base liquid and a sulfide scavenging additive comprising one or more reducing sugars; introducing the treatment fluid into at least a portion of a subterranean formation; and allowing at least a portion of the sulfide scavenging additive to interact with hydrogen sulfide or sulfide ions present in the treatment fluid to produce a precipitate comprising one or more sulfur species.
The present disclosure relates to fluids, additives, and methods for use in subterranean operations, and more specifically, to improved methods and additives for eliminating or reducing concentrations of hydrogen sulfide or soluble sulfide ions for use in subterranean formations and fluids.
Hydrocarbon producing wells may contain many different formation liquids and gases such as methane, ethane, and other higher hydrocarbons, as well as hydrogen sulfide, water, and other compounds. In order to evaluate the commercial value of a hydrocarbon producing well, or as an aid in operations and well planning, it is often useful to obtain information by analyzing the component concentrations of the produced fluid from a formation or an individual well. Numerous systems have been developed to evaluate a downhole fluid composition and the relative component concentrations in the downhole fluid.
Hydrogen sulfide (H2S) is a very toxic, flammable, and pungent gas that causes numerous problems in various aspects of the oil and gas industry. H2S is extremely corrosive to metal, which may damage or destroy tubing, casings, or other types of well bore equipment. H2S also presents health risks to operations personnel that may be exposed to H2S gas at a well site or in processing of well bore fluids. Severe iron sulfide scaling may also choke production, either in the production piping, perforations or within the producing formation itself. Thus, it is typically desirable to reduce or eliminate sulfides from subterranean formations and well bores, among other reasons, to control corrosion rates and to plan for safe development and production of the hydrocarbons.
The release of H25 gas can sometimes be controlled by maintaining the pH of the fluid containing H25 above 10. However, in many cases, it is not practical or possible to maintain this level pH in a fluid for extended periods of time. Sulfide scavengers are often used to react with H25 and convert it to a more inert form. Conventional H2S scavengers include certain aldehydes, certain amine-based chemicals, triazines, copper compounds, hydrogen peroxide, zinc compounds, and iron compounds. However, the reaction products of many of these compounds with H25 are poorly soluble in treatment fluids and/or fluids in the well bore, or may decompose, thereby releasing H2S. Moreover, many conventional sulfide scavengers themselves may have undesirable environmental and/or toxicity problems, and as such may be impractical to use or prohibited altogether in certain circumstances and/or jurisdictions.
SUMMARYThe present disclosure relates to fluids, additives, and methods for use in subterranean operations, and more specifically, to improved methods and additives for eliminating or reducing concentrations of hydrogen sulfide or soluble sulfide ions for use in subterranean formations and fluids.
In one embodiment, the present disclosure provides a method comprising: providing a treatment fluid comprising a base liquid and a sulfide scavenging additive comprising one or more reducing sugars; introducing the treatment fluid into at least a portion of a subterranean formation; and allowing at least a portion of the sulfide scavenging additive to interact with hydrogen sulfide or sulfide ions present in the treatment fluid to produce a precipitate comprising one or more sulfur species.
In another embodiment, the present disclosure provides a method comprising: providing a treatment fluid comprising a base liquid and a sulfide scavenging additive comprising one or more reducing sugars chelated with one or more metal ions; introducing the treatment fluid into at least a portion of a subterranean formation; allowing at least one of the metal ions to interact with hydrogen sulfide or sulfide ions present in the treatment fluid to produce a first product comprising one or more sulfur species; and allowing the reducing sugar to interact with hydrogen sulfide or sulfide ions present in the treatment fluid to produce a second product comprising one or more sulfur species.
In another embodiment, the present disclosure provides a method of treating a fluid comprising a first concentration of hydrogen sulfide or sulfide ions, the method comprising: adding a sulfide scavenging additive comprising one or more reducing sugars to the fluid; and allowing at least a portion of the sulfide scavenging additive to interact with at least a portion of the hydrogen sulfide or sulfide ions in the fluid to reduce the concentration of hydrogen sulfide or sulfide ions to a second concentration that is lower than the first concentration.
The features and advantages of the present disclosure will be readily apparent to those skilled in the art. While numerous changes may be made by those skilled in the art, such changes are within the spirit of the disclosure.
Some specific example embodiments of the disclosure may be understood by referring, in part, to the following description and the accompanying drawings.
While the present disclosure is susceptible to various modifications and alternative forms, specific example embodiments have been shown in the figures and are herein described in more detail. It should be understood, however, that the description of specific example embodiments is not intended to limit the invention to the particular forms disclosed. On the contrary, this disclosure is to cover all modifications and equivalents as illustrated, in part, by the appended claims.
DESCRIPTION OF PREFERRED EMBODIMENTSThe present disclosure relates to fluids, additives, and methods for use in subterranean operations, and more specifically, to improved methods and additives for eliminating or reducing concentrations of hydrogen sulfide or soluble sulfide ions for use in subterranean formations and fluids.
The fluids and sulfide scavenging additives of the present disclosure generally comprise one or more reducing sugars. The term “reducing sugar” is defined herein to include any saccharide that includes an aldehyde functional group or can isomerize to form an aldehyde functional group in basic solution. In certain embodiments, the fluids and sulfide scavenging additives of the present disclosure may be substantially free of compounds having aldehyde functional group prior to placement in basic solution. In certain embodiments, the reducing sugar may be chelated with a metal ion, such as iron. When added to a fluid comprising a liquid, a chelated reducing sugar may interact with H2S and/or sulfide ions present in the fluid to produce one or more sulfur species (e.g., metal sulfides (such as Fe2S3 and FeS) and elemental sulfur), inter alia, in the form of a precipitate that can be removed from the liquid. In certain embodiments, this may be accomplished without further oxidization of the metal ions.
Among the many potential advantages of the present disclosure, the methods and compositions of the present disclosure may, among other things, provide a means of reducing or eliminating concentrations of hydrogen sulfide or soluble sulfide ions in fluids found and/or used in subterranean formations with significantly less risk of environmental damage and/or health and safety hazards. Such methods and compositions may be more compatible with regulatory requirements in various jurisdictions. The sulfide scavenging additives of the present disclosure comprising one or more reducing sugars may be effective at a wider range of pH levels (e.g., pH ranges above about 8) than other sulfide scavenging additives known in the art, and may reduce or eliminate concentrations of hydrogen sulfide or soluble sulfide ions in fluids more effectively. The methods and compositions of the present disclosure also may be more cost effective than other sulfide scavenging methods and additives known in the art.
The reducing sugars used in the methods, fluids, and sulfide scavenging additives of the present disclosure may comprise any reducing sugar (or combination thereof) known in the art. Such reducing sugars may comprise monosaccharides, disaccharides, polysaccharides, and/or combinations thereof. Examples of reducing sugars that may be suitable for use in certain embodiments of the present disclosure include, but are not limited to, glucose, glucosamine, acetyl glucosamine, fructose, sucrose, lactose, maltose, cellobiose, galactose, mannose, ribose, ribulose, xylose, lyxose, rhamnose, arabinose, erythrose, and/or combinations thereof. In certain embodiments, the reducing sugars used in the methods, fluids, and sulfide scavenging additives of the present disclosure may have a molecular weight of from about 180 daltons to about 360 daltons. The reducing sugar optionally may be chelated with any metal ion known in the art, including but not limited to iron, zinc, copper, nickel, manganese, and the like. Chelated reducing sugars that may be suitable for use in certain embodiments of the present disclosure include, but are not limited to, ferric fructose, ferrous sucrose, and the like.
The sulfide scavenging additives used in the present disclosure may exhibit, among other features, an enhanced ability to scavenge sulfides as compared to conventional sulfide scavengers due, at least in part, to the manner in which they react with sulfides and other components of the fluid. In particular, sulfide scavenging additives of the present disclosure that comprise one or more metal ions chelated with reducing sugars may exhibit a dual sulfide scavenging mechanism wherein the metal ion and the reducing sugar each interact with hydrogen sulfide or sulfide ions to produce different products that may be precipitated or otherwise removed from of the fluid. The interaction of the metal ions with hydrogen sulfide or sulfide ions may proceed according to one or more reactions similar those discussed in paragraph [0015] below. The interaction of the reducing sugar with hydrogen sulfide or sulfide ions may involve the degradation of the reducing sugar and the reaction of those degradation products with hydrogen sulfide or sulfide ions. Alternatively, the reducing sugar may interact with hydrogen sulfide or sulfide ions to form an intermediate sulfur-containing compound, the sugar moiety in which may fragment to form other sulfur containing species. The chelation of the reducing sugar with the metal ion also may inhibit the conversion of the metal ion to a metal hydroxide, leaving the metal ion free to interact with and/or scavenge hydrogen sulfide or sulfide ions present in the fluid. However, the reaction mechanisms disclosed herein are provided only as non-limiting illustrations of how the sulfide scavenging additives of the present disclosure may react in certain embodiments, and are not intended to limit the scope of the claims.
One example of a sulfide scavenging additive that may be suitable for use in the present disclosure comprises ferric fructose. In those embodiments, the iron (III) ions in the ferric fructose may react with hydrogen sulfide to produce iron (III) sulfide (Fe2S3). Additionally, the iron (III) ions may be reduced by hydrogen sulfide to their iron (II) oxidation state, producing elemental sulfur (S0) (see Equation (1) below). The reduced iron (II) ion may react with additional hydrogen sulfides to produce iron (II) sulfide (FeS) (see Equation (2) below).
H2S+2Fe3+→S0+2Fe2++2H+ (1)
H2S+Fe2+→FeS+2H+ (2)
In this process, the overall result for the ferric ion in this embodiment of the present disclosure may be expressed according to Equation (3) below:
2H2S+2Fe3+→S0+2FeS+4H+ (3)
The elemental sulfur and iron (II) sulfide may form a precipitate in the fluid being treated, which may be removed from the fluid. Similar reactions may occur using metallic ions other than iron. In embodiments where divalent metallic ions are used, elemental sulfur may not be formed. In addition to the reactions above, the fructose may interact with hydrogen sulfide or sulfide ions to produce various sulfur species that may precipitate or be removed from the fluid being treated.
The reducing sugar (or chelated reducing sugar) may be added to or included in a fluid in any concentration that effectively eliminates or reduces by the desired amount concentrations of H2S or sulfide ions that are present or expected to be present in the fluid. For example, the reducing sugar may be added in a stoichiometric amount relative to the estimated amount of H25 or sulfide ions in the fluid. In certain embodiments, the reducing sugar may be present a fluid in a concentration of about 0.1 to 5 pounds per barrel. As discussed below, an initial amount of the sulfide scavenging additives of the present disclosure comprising one or more reducing sugars may be added to a fluid, and subsequently, additional amounts of the sulfide scavenging additives of the present disclosure may be added to the same fluid. This technique may be used, among other purposes, to increase and/or maintain a concentration of the reducing sugar that is sufficient to effectively eliminate or reduce by the desired amount concentrations of H2S or sulfide ions in the fluid throughout the course of a given operation.
The additives of the present disclosure may be used in conjunction with any fluid, which may include, but are not limited to, treatment fluids introduced into a subterranean formation as well as fluids found in a subterranean formation (e.g., formation water, hydrocarbon fluids, etc.) and/or any combination thereof. The treatment fluids and formation fluids in the present disclosure generally comprise a base liquid, which may comprise any liquid known in the art, such as aqueous liquids, non-aqueous liquids, or any mixture thereof. Where the base liquid comprises an aqueous liquid, it may comprise fresh water, salt water (e.g., water containing one or more salts dissolved therein), brine (e.g., saturated salt water), or seawater. Generally, the water can be from any source, provided that it does not contain compounds that adversely affect other components of the fluid. Where the base liquid comprises a non-aqueous liquid, it may comprise any number of organic liquids. Examples of suitable organic liquids include, but are not limited to, mineral oils, synthetic oils, esters, and the like. In certain embodiments, the treatment fluids and/or formation fluids in the present disclosure may comprise emulsions (including invert emulsions), suspensions, gels, foams, or other mixtures of liquids with solids and/or gases.
The fluids used in the present disclosure optionally may comprise any number of additional additives, including, but not limited to, salts, surfactants, acids, fluid loss control additives, gas, nitrogen, carbon dioxide, surface modifying agents, tackifying agents, foamers, corrosion inhibitors, scale inhibitors, catalysts, clay control agents, biocides, friction reducers, antifoam agents, bridging agents, dispersants, flocculants, additional H2S scavengers, CO2 scavengers, oxygen scavengers, lubricants, viscosifiers, breakers, weighting agents, relative permeability modifiers, resins, particulate materials (e.g., proppant particulates), wetting agents, coating enhancement agents, and the like. A person skilled in the art, with the benefit of this disclosure, will recognize the types of additives that may be included in the fluids of the present disclosure for a particular application.
The methods, fluids, and/or additives of the present disclosure may be used during or in conjunction with any subterranean operation wherein a fluid is used or treated. In certain embodiments, the methods, fluids, and/or additives of the present disclosure may be used in the course of drilling operations. In these embodiments, the methods, fluids, and/or additives of the present disclosure may be used to reduce or eliminate concentrations of H2S from a drilling fluid used in drilling a well or borehole, for example, in a hydrocarbon-bearing subterranean formation where H2S is often encountered. Other suitable subterranean operations may include, but are not limited to, preflush treatments, afterflush treatments, hydraulic fracturing treatments, sand control treatments (e.g., gravel packing), acidizing treatments (e.g., matrix acidizing or fracture acidizing), “frac-pack” treatments, well bore clean-out treatments, and other operations where a treatment fluid may be useful. Such treatment fluids may include, but are not limited to, drilling fluids, preflush fluids, afterflush fluids, fracturing fluids, acidizing fluids, gravel packing fluids, packer fluids, spacer fluids, and the like.
The reducing sugar may be provided in an additive in a solid form, liquid form (e.g., in solution of water or another solvent), or a combination thereof. The sulfide scavenging additives of the present disclosure may be added to a fluid by any means known in the art. The additive may be added to the fluid, for example, in the mud pit before the fluid has circulated or before the fluid contains any detectable amount of sulphur or H2S, as a prophylactic measure against any H2S the fluid may encounter downhole. In certain embodiments, the additive may be added after the fluid has been circulating downhole and has already encountered sulphur or H2S and contains same. In certain embodiments, the amount of the additive added to the fluid may be controlled and/or varied during the course of an operation based on, among other things, the amount of sulfur or H2S detected in fluids exiting the well bore. In these embodiments, any system or technique capable of monitoring or detecting sulfur or H2S content in fluids exiting the well bore may be used. Moreover, the sulfide scavenging additives of the present disclosure may be added to a fluid in multiple portions that are added to the fluid at separate intervals over a period of time. For example, a first amount of a scavenging additive of the present disclosure may be added to a fluid at one point in time in the course of a particular operation. At a subsequent point during that operation, an elevated amount of sulfur or H2S may be detected exiting the well bore, at which point a second amount of a scavenging additive of the present disclosure may be added to the fluid based at least in part on the amount of sulfur or H25 detected.
The exemplary fluids and additives disclosed herein may directly or indirectly affect one or more components or pieces of equipment associated with the preparation, delivery, recapture, recycling, reuse, and/or disposal of the disclosed fluids and additives. For example, and with reference to
As illustrated, the drilling assembly 100 may include a drilling platform 102 that supports a derrick 104 having a traveling block 106 for raising and lowering a drill string 108. The drill string 108 may include, but is not limited to, drill pipe and coiled tubing, as generally known to those skilled in the art. A kelly 110 supports the drill string 108 as it is lowered through a rotary table 112. A drill bit 114 is attached to the distal end of the drill string 108 and is driven either by a downhole motor and/or via rotation of the drill string 108 from the well surface. As the bit 114 rotates, it creates a borehole 116 that penetrates various subterranean formations 118.
A pump 120 (e.g., a mud pump) circulates drilling fluid 122 through a feed pipe 124 and to the kelly 110, which conveys the drilling fluid 122 downhole through the interior of the drill string 108 and through one or more orifices in the drill bit 114. The drilling fluid 122 is then circulated back to the surface via an annulus 126 defined between the drill string 108 and the walls of the borehole 116. At the surface, the recirculated or spent drilling fluid 122 exits the annulus 126 and may be conveyed to one or more fluid processing unit(s) 128 via an interconnecting flow line 130. After passing through the fluid processing unit(s) 128, a “cleaned” drilling fluid 122 is deposited into a nearby retention pit 132 (i.e., a mud pit). While illustrated as being arranged at the outlet of the wellbore 116 via the annulus 126, those skilled in the art will readily appreciate that the fluid processing unit(s) 128 may be arranged at any other location in the drilling assembly 100 to facilitate its proper function, without departing from the scope of the scope of the disclosure.
One or more of the disclosed additives may be added to the drilling fluid 122 via a mixing hopper 134 communicably coupled to or otherwise in fluid communication with the retention pit 132. The mixing hopper 134 may include, but is not limited to, mixers and related mixing equipment known to those skilled in the art. In other embodiments, however, the disclosed additives may be added to the drilling fluid 122 at any other location in the drilling assembly 100. In at least one embodiment, for example, there could be more than one retention pit 132, such as multiple retention pits 132 in series. Moreover, the retention pit 132 may be representative of one or more fluid storage facilities and/or units where the disclosed additives may be stored, reconditioned, and/or regulated until added to the drilling fluid 122.
As mentioned above, the disclosed fluids and additives may directly or indirectly affect the components and equipment of the drilling assembly 100. For example, the disclosed fluids and additives may directly or indirectly affect the fluid processing unit(s) 128 which may include, but is not limited to, one or more of a shaker (e.g., shale shaker), a centrifuge, a hydrocyclone, a separator (including magnetic and electrical separators), a desilter, a desander, a separator, a filter (e.g., diatomaceous earth filters), a heat exchanger, any fluid reclamation equipment, The fluid processing unit(s) 128 may further include one or more sensors, gauges, pumps, compressors, and the like used store, monitor, regulate, and/or recondition the exemplary fluids and additives.
The disclosed fluids and additives may directly or indirectly affect the pump 120, which representatively includes any conduits, pipelines, trucks, tubulars, and/or pipes used to fluidically convey the fluids and additives downhole, any pumps, compressors, or motors (e.g., topside or downhole) used to drive the fluids and additives into motion, any valves or related joints used to regulate the pressure or flow rate of the fluids and additives, and any sensors (i.e., pressure, temperature, flow rate, etc.), gauges, and/or combinations thereof, and the like. The disclosed fluids and additives may also directly or indirectly affect the mixing hopper 134 and the retention pit 132 and their assorted variations.
The disclosed fluids and additives may also directly or indirectly affect the various downhole equipment and tools that may come into contact with the fluids and additives such as, but not limited to, the drill string 108, any floats, drill collars, mud motors, downhole motors and/or pumps associated with the drill string 108, and any MWD/LWD tools and related telemetry equipment, sensors or distributed sensors associated with the drill string 108. The disclosed fluids and additives may also directly or indirectly affect any downhole heat exchangers, valves and corresponding actuation devices, tool seals, packers and other wellbore isolation devices or components, and the like associated with the wellbore 116. The disclosed fluids and additives may also directly or indirectly affect the drill bit 114, which may include, but is not limited to, roller cone bits, PDC bits, natural diamond bits, any hole openers, reamers, coring bits, etc.
While not specifically illustrated herein, the disclosed fluids and additives may also directly or indirectly affect any transport or delivery equipment used to convey the fluids and additives to the drilling assembly 100 such as, for example, any transport vessels, conduits, pipelines, trucks, tubulars, and/or pipes used to fluidically move the fluids and additives from one location to another, any pumps, compressors, or motors used to drive the fluids and additives into motion, any valves or related joints used to regulate the pressure or flow rate of the fluids and additives, and any sensors (i.e., pressure and temperature), gauges, and/or combinations thereof, and the like.
Therefore, the present disclosure is well adapted to attain the ends and advantages mentioned as well as those that are inherent therein. The particular embodiments disclosed above are illustrative only, as the present disclosure may be modified and practiced in different but equivalent manners apparent to those skilled in the art having the benefit of the teachings herein. Furthermore, no limitations are intended to the details of construction or design herein shown, other than as described in the claims below. It is therefore evident that the particular illustrative embodiments disclosed above may be altered or modified and all such variations are considered within the scope and spirit of the present disclosure. While compositions and methods are described in terms of “comprising,” “containing,” or “including” various components or steps, the compositions and methods can also “consist essentially of” or “consist of” the various components and steps. All numbers and ranges disclosed above may vary by some amount. Whenever a numerical range with a lower limit and an upper limit is disclosed, any number and any included range falling within the range is specifically disclosed. In particular, every range of values (of the form, “from about a to about b,” or, equivalently, “from approximately a to b,” or, equivalently, “from approximately a-b”) disclosed herein is to be understood to set forth every number and range encompassed within the broader range of values. Also, the terms in the claims have their plain, ordinary meaning unless otherwise explicitly and clearly defined by the patentee. Moreover, the indefinite articles “a” or “an”, as used in the claims, are defined herein to mean one or more than one of the element that it introduces. If there is any conflict in the usages of a word or term in this specification and one or more patent or other documents that may be incorporated herein by reference, the definitions that are consistent with this specification should be adopted.
Claims
1. A method comprising:
- providing a treatment fluid comprising a base liquid and a sulfide scavenging additive comprising one or more reducing sugars;
- introducing the treatment fluid into at least a portion of a subterranean formation; and
- allowing at least a portion of the sulfide scavenging additive to interact with hydrogen sulfide or sulfide ions present in the treatment fluid to produce a precipitate comprising one or more sulfur species.
2. The method of claim 1 wherein the base liquid comprises an aqueous liquid.
3. The method of claim 1 wherein the treatment fluid comprises a basic solution.
4. The method of claim 1 wherein the treatment fluid is substantially free of aldehydes other than aldehydes formed by the reducing sugars dissolved in the basic solution.
5. The method of claim 1 wherein the pH of the treatment fluid is above 8.
6. The method of claim 1 wherein one or more metal ions is chelated with the one or more reducing sugars.
7. The method of claim 6 wherein the one or more metal ions interact with the hydrogen sulfide or sulfide ions to produce a precipitate comprising one or more metal sulfides.
8. The method of claim 1 wherein the sulfide scavenging additive comprises ferric fructose.
9. The method of claim 1 further comprising adding an additional amount of a sulfide scavenging additive comprising one or more reducing sugars to the treatment fluid after the treatment fluid has been introduced into at least a portion of a subterranean formation.
10. The method of claim 1 wherein:
- the treatment fluid comprises a drilling fluid; and
- the method further comprises using the drilling fluid to drill at least a portion of a well bore penetrating at least a portion of the subterranean formation.
11. A method comprising:
- providing a treatment fluid comprising a base liquid and a sulfide scavenging additive comprising one or more reducing sugars chelated with one or more metal ions;
- introducing the treatment fluid into at least a portion of a subterranean formation;
- allowing at least one of the metal ions to interact with hydrogen sulfide or sulfide ions present in the treatment fluid to produce a first product comprising one or more metal sulfides; and
- allowing the reducing sugar to interact with hydrogen sulfide or sulfide ions present in the treatment fluid to produce a second product comprising one or more sulfur species.
12. The method of claim 11 wherein the base liquid comprises an aqueous liquid.
13. The method of claim 11 wherein the pH of the treatment fluid is above 8.
14. The method of claim 11 wherein the sulfur species in the second product are different from the metal sulfides in the first product.
15. The method of claim 11 further comprising removing the first or second products from the treatment fluid in the form of a precipitate.
16. The method of claim 11 further comprising adding an additional amount of a sulfide scavenging additive comprising one or more reducing sugars to the treatment fluid after the treatment fluid has been introduced into at least a portion of a subterranean formation.
17. A method of treating a fluid comprising a first concentration of hydrogen sulfide or sulfide ions, the method comprising:
- adding a sulfide scavenging additive comprising one or more reducing sugars to the fluid; and
- allowing at least a portion of the sulfide scavenging additive to interact with at least a portion of the hydrogen sulfide or sulfide ions in the fluid to reduce the concentration of hydrogen sulfide or sulfide ions to a second concentration that is lower than the first concentration.
18. The method of claim 17 wherein the fluid comprises an aqueous liquid.
19. The method of claim 17 wherein the pH of the fluid is above 8.
20. The method of claim 17 wherein the fluid is present in at least a portion of a subterranean formation.
Type: Application
Filed: Jun 26, 2013
Publication Date: Jan 1, 2015
Inventor: Cato Russell McDaniel (Montgomery, TX)
Application Number: 13/927,714
International Classification: E21B 21/00 (20060101);
