CN104812868A - Methods for determining reactive index for cement kiln dust, associated compositions, and methods of use - Google Patents

Abstract

A variety of methods and compositions are disclosed, including, in one embodiment, a method of treating a well comprising: providing a treatment fluid comprising a base fluid and a blended cementitious component, wherein the blended cementitious component comprises kiln dust from two or more different sources; and introducing the treatment fluid into a well bore.

Description

Method for determining the reactivity index of cement kiln dust, related compositions and methods of use

technical field

The present invention relates to cementitious components, and more particularly, in certain embodiments, to methods of determining the Reactivity Index of cementitious components.

Background technique

In general, well treatment includes a variety of methods that may be performed in oil, gas, geothermal, and/or water wells, such as drilling, completion, and workover methods. Drilling, completion, and workover methods may include, but are not limited to, drilling, fracturing, acidizing, logging, cementing, gravel packing, perforating, and compliance methods. Many of these well treatments are designed to increase and/or facilitate recovery of desired fluids from subterranean wells. These fluids may include hydrocarbons, such as oil and/or gas.

In cementing methods such as well construction and re-cementing, settable compositions are commonly used. As used herein, the term "settable composition" refers to a composition that hydraulically sets or otherwise develops compressive strength. The settable composition can be used in a cementing operation whereby a tubular string (eg casing and liner) is cemented in the wellbore. During a cement injection, the settable composition may be pumped into the annulus between the formation and a pipe string disposed in the formation or between the pipe string and a larger conduit disposed in the formation. The settable composition should set in the annulus, thus forming an annular sheath of hardened cement (e.g., a cement sheath), which should support and position the tubular string in the wellbore and bond the outer surface of the tubular string to the wellbore walls or larger ducts. The settable composition may also be used in recementing methods, such as placing cement plugs; and squeezing cement to seal voids in pipe strings, cement jackets, gravel packs, formations, and the like. The settable compositions can also be used in surface applications, such as building cementing.

Settable compositions for formations typically may include cementitious components that hydraulically set or otherwise harden to develop compressive strength. Examples of cementitious components that may be included in the settable composition include Portland cement, calcium aluminate cement, cement kiln dust, lime kiln dust, fly ash, slag, pumice and rice hull ash, among others. The properties of these different cementitious components in a settable composition can vary and can even vary for a particular cementitious component depending, for example, on the particular type or source of the component. For example, some of these cementitious components may have undesirable properties that may render them unsuitable for well treatment. In addition, variations in the properties of cementitious components can lead to a lack of predictability and consistency of cementitious components when used in treatment fluids. This lack of predictability, consistency can be evident even for the same cement-based component eg when sourced from different locations.

Contents of the invention

The present invention relates to cementitious components, and more particularly, in certain embodiments, to methods of determining the Reactivity Index of cementitious components.

One embodiment discloses a method of treating a well comprising: providing a treatment fluid comprising a base fluid and a blended cement-based component, wherein the blended cement-based component comprises kiln dust; and introducing the treatment fluid into the wellbore.

Another embodiment discloses a method of cementing comprising: providing a settable composition comprising water and an admixed cementitious component, wherein the admixed cementitious component comprises kiln dust of various origins; and coagulating said settable composition to form a hardened mass.

Another embodiment discloses a method of cementing comprising: providing a settable composition comprising water and an admixed cementitious component, wherein the admixed cementitious component comprises kiln dust and an additional cement a base component, the kiln dust and the additional cement-based component each have a defined reactivity index; and set the settable composition to form a hardened mass.

Another embodiment discloses a method of preparing a blended cementitious component comprising: providing a first kiln dust from a first source; providing a second kiln dust, the second kiln dust from a second source; and blending at least said first kiln dust with said second kiln dust to form said blended cementitious component.

Another embodiment discloses a method of measuring reactivity of kiln dust, comprising: measuring a parameter of said kiln dust, said kiln dust having a specific surface area; and dividing said measured parameter by said kiln dust The above specific surface area is used to obtain the reactivity index of the kiln dust.

Another embodiment discloses a well treatment fluid comprising: a base fluid; and a blended cementitious component comprising kiln dust from two or more different sources.

The features and advantages of the present invention 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 invention.

Description of drawings

These figures illustrate certain aspects of some embodiments of the invention and should not be used to limit or define the invention.

Figure 1 is a graph showing measured response indices for cement kiln dust from various sources.

Figure 2 is a graph comparing actual versus predicted compressive strength of dry blends of cement kiln dust.

Figure 3 is a graph comparing actual versus predicted volume average apparent viscosity at 511 sec ^-1 for dry blends of cement kiln dust.

Figure 4 is a graph comparing actual versus predicted volume average apparent viscosity of dry blends of cement kiln dust at 51 sec ⁻¹ .

detailed description

The present invention relates to cementitious components, and more particularly, in certain embodiments, to methods of determining the Reactivity Index of cementitious components. By determining the Reactivity Index of cement-based components, blends of cement-based components can be used in well treatment, which, according to certain embodiments, can provide more predictable and consistent performance. Additionally, additional embodiments may include the use of a defined response index to provide admixtures of cementitious components in which one or more parameters have been optimized, including, for example, compressive strength, Young's modulus (Young's Modulus), Fluid loss and/or thickening time.

Without being bound by theory, the reactivity index of a cementitious component may be referred to as a measure of the reactivity of the cementitious component, as adjusted for differences in surface area. An exemplary technique for determining the response index may include measuring a parameter of the cement-based component, and then dividing the measured parameter by the specific surface area of the cement-based component. In some embodiments, the Reactivity Index of the cementitious component can be calculated according to the following equation:

RI=MP/SSA

where RI is the Reactivity Index, MP is the measured parameter of the cementitious component, and SSA is the specific surface area of the cementitious component. In general, specific surface area is a property of particulate solids and, as used herein, is defined as the total surface area of the cementitious component divided by the mass of the cementitious component or the total surface area divided by the gross volume of the cementitious component.

In general, cement-based components are particulate solids that hydraulically set or otherwise harden in the presence of water to develop compressive strength. Non-limiting examples of cementitious components that may be suitable for use in embodiments of the present invention include Portland cement, calcium aluminate, gypsum, pozzolan materials, and kiln dust. Mixtures of one or more different cementitious components may also be used. In some embodiments, cementitious components may be combined with lime.

In some embodiments, the cementitious component may comprise Portland cement. Portland cement is a common cement-based component that hydraulically reacts with water to develop compressive strength. Examples of suitable Portland cements may include those classified as Classes A, C, G, and Hcements according to the American Petroleum Institute, API Specification for Materials and Testing for Well Cements, API Specification 10, Fifth Edition, July 1, 1990. Additionally, Portland cements suitable for use in embodiments of the present invention may also include those classified as ASTM Type I, I/II, II, III, IV, or V. In some embodiments, admixtures of cementitious components comprising Portland cement may be used.

In some embodiments, the cementitious component may comprise calcium aluminate. Calcium aluminate can react hydraulically with water to develop compressive strength. Calcium aluminate may be included in cements commonly referred to as calcium aluminate cements or high alumina content cements. Calcium aluminate cement can be prepared in a manufacturing process that includes mixing calcium-containing material (eg, limestone) and aluminum-containing material (eg, bauxite).

In some embodiments, the cementitious component may comprise gypsum. Gypsum is a material that sets in the presence of water to develop compressive strength. Gypsum may be included in cement commonly referred to as gypsum cement. For use in cement, in some cases gypsum can be burned at extremely high temperatures and then ground. In certain embodiments, gypsum may be added to Portland cement.

In some embodiments, the cementitious component may include pozzolanic materials. Pozzolanic materials that may be suitable include a variety of natural or man-made materials that exhibit cementitious properties in the presence of calcium hydroxide. Examples of suitable pozzolan materials that may be suitable for use in embodiments of the present invention include natural and man-made pozzolans such as fly ash, silica fume, slag, burnt shale, burnt clay, metakaolin, pumice, diatomaceous earth, pozzolans, opalescent Shale, tuff; and burned organic materials such as agricultural waste ash, municipal waste ash (e.g., municipal solid waste ash), wastewater treatment waste ash, animal waste ash, non-human non-animal industrial waste ash and their combinations. Specific examples of agricultural waste ash include, for example, rice hull ash, wood (e.g., sawdust, bark, twigs, twigs, other waste wood) ash, leaf ash, corn cob ash, sugar cane (e.g., sugar cane) ash, Bagasse ash, grain (e.g., amaranth, barley, corn, linseed, millet, oats, quinoa, rye, wheat, etc.) and related by-product (e.g., hulls, hulls, etc.) ash, orchard ash, vine shears Chip ash, grass (eg, Korai, Tifton, native shiba, etc.) ash, straw ash, ground nut shell ash, legume (eg, soybean) ash, and combinations thereof.

In some embodiments, the cementitious component may comprise kiln dust. An example of kiln dust includes cement kiln dust. Cement kiln dust, as the term is used herein, refers to partially calcined kiln feed that is removed from the gas stream during cement production and collected, for example, in a dust collector. Cement kiln dust can generally exhibit cementitious properties because it can set and harden in the presence of water. Typically, large quantities of cement kiln dust are collected during cement production and are usually disposed of as waste. Disposal of cement kiln dust can add unwanted costs to cement manufacturing and environmental concerns associated with its disposal. Chemical analysis of cement kiln dust from various cement manufacturers varies depending on many factors, including the specific kiln feed, the efficiency of the cement production operation, and the associated dust collection system. Cement kiln dust can typically contain various oxides such as _SiO2 , _Al2O3 , _Fe2O3 , _CaO , _MgO , _SO3 , _Na2O and _K2O . Another example of kiln dust includes lime kiln dust. Lime kiln dust, as the term is used herein, refers to the product produced during the manufacture of lime. Lime kiln dust may be collected during the calcination of limestone, for example by a dust control system.

In some embodiments, one or more parameters of the cementitious component can be measured and then used to determine the response index. Parameters can include many different parameters that can be measured using standard laboratory testing techniques for settable compositions comprising cementitious components and water. Additional components may also be included in the settable composition, for example, to alter one or more properties of the treatment fluid. Parameters that can be measured of cementitious components or settable compositions contained therein include, for example, compressive strength, Young's modulus, fluid loss, thickening time, rheological values (e.g., volume average apparent viscosity, plastic viscosity, yield point, etc.) and/or free water.

Compressive strength is generally the ability of a material or structure to withstand an axially oriented thrust. The compressive strength of the cement-based component can be measured for a specified time after the cement-based component has been mixed with water and the resulting treatment fluid maintained under specified temperature and pressure conditions. For example, compressive strength can be measured at times ranging from about 24 to about 48 hours after the fluids are mixed and the fluids are maintained at a temperature of 170°F and atmospheric pressure. Compressive strength can be measured by destructive or non-destructive methods. Destructive Method The strength of the treatment fluid samples was physically tested at various time points by crushing the samples in a compression testing machine. Compressive strength is calculated by dividing the load to failure by the cross-sectional area resisting the load and is reported in pounds force per square inch (psi). Nondestructive methods typically use an Ultrasonic Cement Analyzer ("UCA") available from FannInstrument Company, Houston, TX. Compressive strength can be determined according to API RP 10B-2, Recommended Practice for Testing Well Cements, First Edition, July 2005.

Young's modulus, also known as modulus of elasticity, is a measure of the relationship of applied stress to resulting strain. In general, highly deformable (plastic) materials will exhibit lower modulus as the confinement stress increases. Thus, Young's modulus is the elastic constant that demonstrates the ability of the tested material to withstand an applied load. A number of different laboratory techniques can be used to measure the Young's modulus of a treatment fluid comprising a cementitious component after the treatment fluid has been allowed to set under defined temperature and pressure conditions for a period of time.

Fluid loss typically refers to the loss of fluids, such as treatment fluids, into the formation. A number of different laboratory techniques can be used to measure the fluid loss of the treatment fluid to give an indication of the properties of the treatment fluid in the well. Fluid loss can be measured using a static fluid loss test, with a static or agitated fluid loss cell, according to the previously mentioned API RP Practice 10B-2.

Viscosification time typically refers to the time a fluid, such as a treatment fluid comprising a cement-based component, remains in a fluid state capable of being pumped. A number of different laboratory techniques can be used to measure thickening time to give an indication of the amount of time the treatment fluid will remain pumpable in the well. An exemplary technique for determining whether a treatment fluid is in a pumpable fluid state may use high temperature under specified pressure and temperature conditions according to the procedure for determining cement thickening time set forth in the previously mentioned API RP Practice 10B-2. high pressure consistency meter. The thickening time may be the time for the treatment fluid to reach a consistency ("Bc") of 70 Bearden units and may be reported as the time to reach 70 Bc.

The rheological value of a fluid can be determined to characterize the rheological properties of the fluid. Rheological values that can be determined include, inter alia, volume-average apparent viscosity, yield point and plastic viscosity. Plastic viscosity is typically a measure of a fluid's resistance to flow. In some embodiments, the yield point can be a parameter of the Bingham plastic model, the yield point being the slope of the shear stress/shear rate line above the yield point. Yield point is typically a measure of the point at which a material can no longer be elastically deformed. In some embodiments, the yield point can be a parameter of the Bingham plasticity model, the yield point being the yield stress extrapolated to a shear rate of zero. A number of different laboratory techniques can be used to measure the rheological values of the treatment fluid to give an indication of the properties of the treatment fluid in the well. Rheological values can be determined according to the procedure set forth in API RP Practice 10B-2.

Free water typically refers to any water in a fluid in excess necessary to fully hydrate the components of the fluid. Free water may be undesirable because it may physically separate from the cementitious composition as it sets. Free water may also be referred to as free fluid. A number of different laboratory techniques can be used to measure the free water of a treatment fluid to give an indication of the properties of the treatment fluid in the well. Free water can be determined according to the procedure set forth in APIRP Practice 10B-2.

As previously mentioned, the reactivity of cementitious components can vary between different types of cementitious components or even between different sources for a particular type of cementitious component. For example, Portland cement may differ in reactivity with another cement-based component, such as a pozzolan material. By way of further example, the reactivity of cement-based components for cement-based components can vary between different sources. In some embodiments, the response index of the cementitious component can vary by a factor of at least about 2:1 between two or more different sources. For example, the response index of the cementitious component can vary between different sources between and/or include any of the following amounts: about 2:1, about 10:1, about 50: 1. About 100:1, about 250:1, about 500:1 or about 1000:1. Because reactivity varies between different cement-based components and even between different sources for cement-based components, the performance of different cement-based components can be unpredictable and can also lead to Lack of consistency when in a liquid (such as a settable composition). In some cases, the properties of a particular cementitious component may have undesirable properties, which may render it unsuitable for use. For example, cement-based components from certain sources may have properties that render them undesirable for use.

In some embodiments, a blend of two or more different cementitious components can be used to provide a blended cementitious component that can have properties suitable for a particular application. This may be particularly applicable, for example, where one of the cementitious components in the admixture may have properties that make it unsuitable for a particular application. For example, a cement-based component such as cement kiln dust from a first source may be blended with a cement-based component such as cement kiln dust from a second source. In some embodiments, one or both of the cementitious components may have a reactivity that is unsuitable for a particular application. For example, the reactivity of each cementitious component may individually be too slow or too fast for a particular application. A blend of cementitious components from two different sources can form a blended cementitious component with compressive strength properties suitable for the application. In some embodiments, the relative proportions (eg, weight fractions) of each cementitious component in the blended cementitious component can then be adjusted to adjust the compressive strength properties of the blended cementitious component.

The two or more cement-based components of the blended cement-based components may include, for example, two or more different types of cement-based components, such as Portland cement and cement kiln dust. Alternatively, the two or more cement-based components of the blended cement-based components may include, for example, cement-based components from two or more different sources. For example, the first cement-based component may comprise cement kiln dust from a first source, and the second cement-based component may comprise cement kiln dust from a second source. It should be understood that embodiments are not limited to only two different sources, but may include cementitious components, such as cement kiln dust, from three, four, five or even more different sources. The two or more different sources of cement-based components may include different manufacturers, different cement manufacturing plants, and the like. Cement-based components such as cement kiln dust that are by-products from cement manufacturing plants can have many different sources available throughout the world. For example, different sources of cement kiln dust may include different manufacturing plants throughout the world that may generate cement kiln dust.

Two or more cementitious components may be blended, for example, prior to combination with water and/or other components of the treatment fluid to form a blended cementitious component. In certain embodiments, two or more cementitious components may be dry blended to form a dry blend comprising two or more cementitious components. The dry blend can then be combined with water and/or other components in any order to form a treatment fluid. However, use of the term "blend" is not intended to imply that the two or more cementitious components have been dry blended prior to combination with water. For example, a blend of two or more cement-based components may not be combined until after one or even both of the cement-based components have been blended with water.

In some embodiments, the response index can be used to optimize a blended cementitious component, where the blended cementitious component comprises two or more cementitious components. For example, the response index can be used to optimize one or more parameters of the blended cementitious components, including compressive strength, Young's modulus, fluid loss, and/or thickening time. Optimizing the blended cementitious components may include determining the reactivity index of each cementitious component in the blended cementitious components. The reactivity index of the cementitious component can then be used to predict the performance of the blended cementitious component. The ratio of each cementitious component can be adjusted to optimize the properties of the blended cementitious component. The properties of the blended cementitious components can be optimized with the properties of the blended cementitious components estimated using the following equation:

where EP _blending is an estimated parameter of the cementitious component to be blended, i is an individual cementitious component from a set of cementitious components 1 to n, n is an integer, and RI _i is the response of cementitious component i index, SSA _i is the specific surface area of cement-based component _i , fi is the mass fraction of cement-based component i, and m is a number from 1 to 10. The set of cementitious components may comprise 2 or more different cementitious components. The two or more different cement-based components may be different types of cement-based components, such as Portland cement and slag, or may be from different sources, such as cement kiln dust from a first source and cement kiln dust from a second source. Cement kiln dust. In some embodiments, m can be 1. In an alternative embodiment, m may be 7/3.

In some embodiments, the average particle size of the cementitious component may vary from its original particle size. The response index can then be measured for the altered cementitious components. Altered cementitious components may be included in the blended cementitious components. According to embodiments of the present invention, the average particle size of the cementitious component may be altered using any suitable technique, including but not limited to grinding or separation to provide a material having an altered particle size. Separating the cement-based component may include screening or any other suitable technique for separating the cement-based component to provide an average particle size that has been altered from its original size. For example, screening can be used to produce cementitious components with increased or decreased average particle sizes as desired for a particular application. As a further example, grinding can be used to reduce the average particle size of the cementitious component. A combination of grinding and separation may be used in some embodiments. As used herein, the term "ground/grinding" means the use of a grinder (eg, ball mill, rod mill, etc.) to reduce the particle size of a specified component. An example of a suitable grinder is the 8000 Mixer/Mixer available from SPEX Sample Prep ball mill. In some embodiments, the cementitious component may be ground for a period of time ranging from about 30 minutes to about 1 hour.

The average particle size of the cementitious components can vary to any size suitable for use in cementitious operations. In some embodiments, the average particle size of the cementitious component can be varied from its original particle size to have an average particle size in the range of about 1 micron to about 350 microns. The average particle size corresponds to the d50 value as measured by a particle size analyzer such as those manufactured by Malvern Instruments, Worcestershire, United Kingdom.

In some embodiments, the average particle size of the cementitious component may increase from its original size. For example, the average particle size of the cementitious component can be at least 5% larger than its original size. In some embodiments, at least a portion of the cement-based component may increase to a size ranging from about 5% to about 500% larger than its original size. In some embodiments, the average particle size may increase to a size within a range between and/or including any of the following: about 5%, about 10%, about 20% larger than its original size , about 30%, about 40%, about 50%, about 60%, about 70%, about 80%, about 90%, about 100%, about 200%, about 300%, about 400%, or about 500%.

In some embodiments, the average particle size of the cementitious component can be reduced from its original size. For example, the average particle size can be reduced by an amount sufficient to increase the compressive strength of the cementitious component. In some embodiments, the cementitious component can have an average particle size that is at least 5% smaller than its original size. In some embodiments, at least a portion of the cement-based component can be reduced to have an average particle size in the range of about 5% to about 95% of its original size. For example, the average particle size can be reduced to a size within a range between and/or including any of the following: about 5%, about 10%, about 15%, about 20%, about 25% %, about 30%, about 35%, about 40%, about 45%, about 50%, about 55%, about 60%, about 6%, about 70%, about 75%, about 80%, about 90%, or About 95% of its original size. For example, the reduced particle size cementitious component can have an average particle size of less than about 15 microns. In some embodiments, the reduced particle size cementitious component may have an average particle size of less than about 10 microns, less than about 5 microns, less than about 4 microns, less than about 3 microns, less than about 2 microns, or less than about 1 micron. In particular embodiments, the reduced particle size cementitious component can have an average particle size ranging from about 0.1 micron to about 15 microns, from about 0.1 micron to about 10 microns, or from about 1 micron to about 10 microns. Those of ordinary skill in the art, having the benefit of this disclosure, should be able to select the cementitious component particle size suitable for a particular application.

In some embodiments, the average particle size of the cement kiln dust can be reduced by an amount sufficient to provide an increase in compressive strength to the settable composition. For example, the average particle size can be reduced to provide an increase in compressive strength of at least about 5%, about 25%, about 50%, about 75%, or about 100%.

According to embodiments of the present invention, cementitious components may be included in treatment fluids that may be used in a variety of operations that may be performed in a formation. Cementitious components may have a Reactivity Index calculated according to the disclosed embodiments. In some embodiments, blended cementitious components may be used. In some embodiments, the Response Index can be used to determine the cementitious component of a particular blend of cementitious components. As referred to herein, the term "treatment fluid" shall be understood to mean any fluid that may be used in subterranean applications in conjunction with a desired function and/or for a desired purpose. The term "treatment fluid" is not intended to imply any specific function of the fluid. Treatment fluids are commonly used, for example, in drilling, completion and stimulation operations. Examples of the treatment fluid include drilling fluid, well washing fluid, workover fluid, compliance fluid, gravel packing fluid, acidizing fluid, fracturing fluid, cement composition, spacer fluid, and the like.

While embodiments of the compositions and methods may be used in a variety of applications, they may be particularly useful in subterranean well completion and reinjection operations, such as primary cementing of casings and linings in wellbores. It may also be suitable for surface cementing operations, including construction cementing operations. Accordingly, embodiments of the present invention disclose settable compositions comprising cementitious components and water.

Cementitious components may be included in embodiments of the settable composition in amounts suitable for a particular application. In some embodiments, the cementitious component may comprise cement kiln dust. Cement kiln dust may be present in an amount ranging from about 0.01% to 100% by weight of cement-based component ("bwoc"). For example, cement kiln dust may be present in an amount ranging between and/or including any of the following: about 0.01%, about 5%, about 10%, about 20%, about 30% %, 40%, about 50%, about 60%, about 70%, about 80%, about 90%, or about 100%. The cement-based component may be free or substantially free (eg, not exceeding 1% by weight of the cement-based component) of any additional cement-based component other than said cement-based component. In some embodiments, the cement-based component may be substantially free of Portland cement. One of ordinary skill in the art, having the benefit of this disclosure, should be able to determine the proper inclusion of cementitious components for a particular application.

Water used in embodiments of the settable compositions of the present invention may include, for example, fresh water, brine (e.g., water containing one or more salts dissolved therein), brine (e.g., saturated brine produced from a formation), Sea water or any combination thereof. In general, the water can be from any source provided, for example, it does not contain excessive amounts of compounds that might undesirably affect other components of the settable composition. In some embodiments, water may be included in an amount sufficient to form a pumpable slurry. In some embodiments, water may be included in the settable compositions of the present invention in an amount ranging from about 40% to about 200% bwoc. For example, water may be present in an amount ranging between and/or including any of the following by weight of the cement: about 50%, about 75%, about 100%, about 125%, About 150% or about 175%. In particular embodiments, water may be included in an amount ranging from about 40% to about 150% bwoc. Those of ordinary skill in the art having the benefit of this disclosure will recognize the appropriate inclusion of water for a chosen application.

Other additives suitable for use in subterranean cementing operations may also be added to embodiments of the settable composition according to embodiments of the present invention. Examples of such additives include, but are not limited to, fluid loss control additives, set retarders, strength decay additives, set accelerators, weighting agents, lightweight additives, gas generating additives, mechanical property enhancing additives, lost circulation materials, filtration Control additives, blowing additives, thixotropic additives and any combination thereof. Specific examples of these and other additives include crystalline silica, amorphous silica, fumed silica, salts, fibers, hydratable clays, calcined shale, vitrified shale, microspheres, hollow glass spheres, Fly ash, diatomaceous earth, metakaolin, ground perlite, rice hull ash, natural pozzolans, zeolites, cement kiln dust, resins, any combination thereof, etc. Those of ordinary skill in the art, having the benefit of this disclosure, will readily be able to determine the type and amount of additive suitable for a particular application and desired result.

Those of ordinary skill in the art will appreciate that embodiments of settable compositions should generally have a density suitable for a particular application. For example, embodiments of the settable composition can have a density of about 4 pounds per gallon ("lb/gal") to about 20 lb/gal. In certain embodiments, the settable composition may have a density of about 8 lb/gal to about 17 lb/gal. Embodiments of the settable composition may be foamed or non-foamed, or may contain other means to reduce their density, such as hollow microspheres, low density elastic beads, or other density reducing means known in the art additive. Additionally, the settable composition may contain weighting agents or other means to increase its density. One of ordinary skill in the art with the benefit of this disclosure will recognize the appropriate density for a particular application.

In some embodiments, the settable composition may have a temperature of greater than about 1 hour at 3,000 psi and a temperature ranging from about 50°F to about 400°F, or from about 80°F to about 250°F, and alternatively at a temperature of about 140°F. , or a thickening time greater than about 2 hours, or greater than about 5 hours. In some embodiments, the settable composition may have a pressure of about 100 psi to about 10,000 psi and alternatively a 24 hour compressive strength in the range of about 350 psi to about 3,000 psi.

The components of the settable composition may be combined in any order desired to form a settable composition that can be placed into the formation. Additionally, the components of the settable composition may be combined using any mixing device compatible with the composition, including, for example, a batch mixer. In some embodiments, a dry blend may first be formed from a cementitious component or a mixture of cementitious components. The dry blend can then be combined with water to form a settable composition. Other suitable techniques may be used to prepare settable compositions, as will be apparent to those of ordinary skill in the art in light of embodiments of the present invention.

As will be appreciated by those of ordinary skill in the art, embodiments of the cementitious compositions of the present invention may be used in a variety of cementing operations, including surface and subterranean operations, such as primary cementing and re-cementing. In some embodiments, a cement composition comprising a cement-based component and water may be provided and allowed to set. In certain embodiments, cementitious compositions may be introduced into the formation and allowed to set therein. As used herein, introducing a cement composition into a formation includes introducing into any portion of a formation, including, but not limited to, into a wellbore drilled into the formation, into a near-wellbore region surrounding the wellbore, or into both.

In one-time cementing embodiments, for example, embodiments may include providing a cement composition, introducing the cement composition into the wellbore annulus; and allowing the cement composition to set in the annulus to form a hardened mass. The wellbore annulus may include, for example, the annular gap between the conduit (eg, tubing string, liner, etc.) and the wellbore wall or between the conduit and a larger conduit in the wellbore. In general, the hardened substance should hold the catheter in the wellbore in most cases.

In recementing embodiments, the cement composition may be used, for example, in squeeze cementing operations or to place cement plugs. For example, the cement composition can be placed in the wellbore to plug openings, such as voids or cracks in formations, gravel packs, conduits, cement casings, and/or microannulus between cement casings and conduits or formations . An example of such a method may include placing a cement composition in the void, and allowing the cement composition to set in the void.

While the above description refers to the use of cementitious components in cementing methods, it should be understood that embodiments of the present technology also encompass the use of cementitious components in any of a variety of different subterranean treatments. Cementitious components may have a Reactivity Index determined according to disclosed embodiments. In some embodiments, blended cementitious components may be used. In some embodiments, the Response Index can be used to determine the amount of cement-based component in a particular blend of cement-based components. An exemplary method may include a subterranean treatment method comprising providing a treatment fluid comprising a cement-based component and introducing the treatment fluid into the formation. For example, a drilling fluid may contain a cement-based component, wherein the drilling fluid may be circulated down through the drill pipe and drill bit and then up through the wellbore to the surface. The drilling fluid used can be a variety of fluids (gas or liquid) and mixtures of fluids and solids (such as solid suspensions, mixtures and emulsions).

In some embodiments, the spacer fluid may comprise a cementitious component, which may have a reactivity index determined according to the disclosed embodiments. The spacer fluid can be used, for example, to displace fluid from the wellbore. In one embodiment, the fluid displaced by the spacer fluid comprises drilling fluid. For example, spacer fluids may be used to displace drilling fluid from the wellbore. Drilling fluids may include, for example, various fluids such as solid suspensions, mixtures, and emulsions. Additional steps in embodiments of the method may include introducing the tubing string into the wellbore, introducing the cement composition into the wellbore, the spacer fluid separating the cement composition from the first fluid. In one embodiment, the cement composition can be allowed to set in the wellbore. A cement composition may include, for example, cement and water. In some embodiments, at least a portion of the spacer fluid may remain in the wellbore where the spacer fluid congeals to form a hardened mass.

Example

In order to facilitate a better understanding of the invention, the following examples of certain aspects of some embodiments are given. The following examples should in no way be construed as limiting or defining the full scope of the invention.

Example 1

The response index for the compressive strength of thirty three different cement kiln dust samples (designated samples A to GG) was determined and presented in FIG. 1 . The CKD samples were each from a different supply source. The response indices of the thirty three CKD samples were determined by dividing the measured 24 hour compressive strength of the settable composition by the specific surface area of the CKD sample. The specific surface area of each CKD sample was determined by dividing the total surface area of a particular CKD sample by the sample mass. Surface area was determined using a Malvern particle size analyzer. The 24 hour compressive strength of each CKD sample was determined by first preparing a settable composition comprising the CKD sample in an amount of 100% bwoc and water in an amount sufficient to provide a density of about 13 lb/gal. After preparation, the settable composition was allowed to cure for 24 hours in a 2"x4" metal cylinder, which was placed in a water bath at 170°F to form a set cement cylinder. Immediately after removal from the water bath, the destructive compressive strength was determined using a mechanical press according to API RP 10B-2.

Example 2

Blended cementitious components were prepared comprising a mixture of CKD samples from Example 1 as indicated in the table below. The determined response indices for the CKD samples were then used in the following equations to predict the performance of each blended cementitious component.

CS _Blend = (RI _Z )(SSA _Z )(f _Z ) ^m ₊ (RI _F )(SSA _F )(f _F ) ^m + (RI _E )(SSA _E )(f _E ) ^m

where CS _Blend is the estimated compressive strength of the blended cement-based component, RI _Z is the response index of the compressive strength of CKD sample Z and is 6.9, m is 1, SSA _Z is the specific surface area of CKD sample Z and is 2.32 , f _Z is the mass fraction of CKD sample Z, RI _F is the response index of compressive strength of CKD sample F and is 105, SSA _F is the specific surface area of CKD sample F and is 2.33, f _F is the mass fraction of CKD sample F, RI _E is the response index of the compressive strength of CKD sample E and is 107, SSA _E is the specific surface area of CKD sample E and is 3.6, and f _E is the mass fraction of CKD sample E.

The estimated compressive strength values of the blended cementitious components were then compared to the actual 24 hour compressive strength values of the blended cementitious components. The 24-hour compressive strength of each blended cementitious component was determined by first preparing a settable composite containing the blended cementitious component in an amount of 100% bwoc and water in an amount sufficient to provide a density of 13 lb/gal. combination. Cement dispersant (CFR-3® cement friction reducer, from Halliburton Energy Services, Inc.) in an amount of 0.5% bwoc to 1.0% bwoc was added to some samples and should not affect the measured compressive strength values. After preparation, the settable composition was allowed to cure for 24 hours in a 2"x4" metal cylinder, which was placed in a water bath at 140°F to form a set cement cylinder. Immediately after removal from the water bath, the destructive compressive strength was determined using a mechanical press according to API RP 10B-2.

A plot of actual compressive strength values versus estimated compressive strength values is provided on FIG. 2 . As shown on Figure ² , the plotted values have an R value of 0.952 and a slope of 0.9253. Estimated and actual compressive strength values for the blended cementitious components are also provided in Table 1 below.

Table 1

Example 3

The Response Index for volume average apparent viscosity at 511 sec ⁻¹ and 51 sec ⁻¹ was determined for CKD samples Z, F and E from Example 1 and is provided in Table 2 below. The reactivity index for these samples was determined by dividing the measured volume average apparent viscosity of the settable composition by the specific surface area of the CKD samples. The specific surface area of each CKD sample was determined by dividing the total surface area of a particular CKD sample by the sample mass. Surface area was determined using a Malvern particle size analyzer. The 24 hour volume average apparent viscosity ("VAV") of each CKD sample was determined by first preparing a condensable combination comprising the CKD sample in an amount of 100% bwoc and water in an amount sufficient to provide a density of about 12 lb/gal thing. The volume average apparent viscosity at 511 sec ^-1 and 51 sec ^-1 was measured according to API RP 10B-2.

Table 2

Subsequently, a blended cementitious component was prepared comprising a mixture of CKD samples Z, F, E as indicated in the table below. The determined response indices at 511 sec ⁻¹ and 51 sec ⁻¹ for the CKD samples were then used in the following equations to predict the performance of each blended cementitious component.

VAV _Blend = (RI _Z )(SSA _Z )(f _Z ) ^m ₊ (RI _F )(SSA _F )(f _F ) ^m + (RI _E )(SSA _E )(f _E ) ^m

where VAV _blend is the estimated volume-average apparent viscosity of the blended cement-based component, RI _Z is the response index for the volume-average apparent viscosity of CKD sample Z, SSA _Z is the specific surface area of CKD sample Z, and f _Z is The mass fraction of CKD sample Z, m is 7/3, RI _F is the reaction index of the volume average apparent viscosity of CKD sample F, SSA _F is the specific surface area of CKD sample F, f _F is the mass fraction of CKD sample F, RI _E is the response index of the volume-average apparent viscosity of CKD sample E, SSA _E is the specific surface area of CKD sample E, and _fE is the mass fraction of CKD sample E.

The estimated volume average apparent viscosities at 511 sec ^-1 and 51 sec ^-1 of the blended cement-based components were then compared to the actual volume average apparent viscosities at 511 sec ^-1 and 51 sec ^-1 of the blended cement-based components . The volume average apparent viscosity of each blended cementitious component was determined by first preparing a commercially available viscoelastic containing the blended cementitious component in an amount of 100% bwoc and water in an amount sufficient to provide a density of 12 lb/gal. Congeal the composition. After preparation, the volume average apparent viscosity at 511 sec ^-1 and 51 sec ^-1 was determined according to API RP 10B-2.

Graphs of actual volume average viscosity values versus estimated volume average viscosity values are provided on FIGS. 3 and 4 . As shown on Figure 3, the plotted values at 511 sec ^-1 have an R2 value of ^0.9894 and a slope of 0.9975. As shown on Figure ⁴ , the plotted values at 51 sec ^-1 have an R2 value of 0.9931 and a slope of 0.9814. Estimated and actual volume average viscosity values for the blended cementitious components are also provided in Table 2 below.

table 3

It should be understood that the compositions and methods may be described in terms of "comprising", "containing" or "comprising" various components or steps, and that the compositions and methods may also "consist essentially of" or "consist of" each of the components and steps. Components and steps "consist of". Furthermore, the indefinite article "a/an" as used in the claims is defined herein to mean one or more than one element to which it introduces.

For the sake of brevity, only certain ranges are explicitly disclosed herein. However, a range from any lower limit may be combined with any upper limit to recite a range not expressly recited, and a range from any lower limit may be combined with any other lower limit to recite a range not expressly recited, in the same way a range from any upper limit may be Combined with any other upper limit to recite a range not expressly recited. Additionally, whenever a numerical range having a lower limit and an upper limit is disclosed, any number and any included range falling within that range is specifically disclosed. In particular, each range of values disclosed herein (of the form "about a to about b" or equivalently "about a to b" or equivalently "about a-b") is to be understood as setting forth the broader range of values Every number and range covered within a range (even if not expressly recited). Thus, each point or individual value may serve as its own lower or upper limit, in combination with any other point or individual value or any other lower or upper limit, to recite a range not expressly recited.

Accordingly, the present invention is well adapted to attain the ends and advantages mentioned as well as those inherent therein. The particular embodiments disclosed above are illustrative only, as the invention may be modified and practiced in different but equivalent manners apparent to those skilled in the art having the benefit of the teachings herein. While individual embodiments are discussed, this invention encompasses all combinations of all those embodiments. Furthermore, no limitations are intended to the details of construction or design herein presented, other than as described in the claims below. Also, the terms in the claims have their plain, ordinary meaning unless otherwise explicitly and clearly defined by the patentee. 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 invention. In the event of any conflict in the usage of a word or term in this specification and one or more patents or other documents that may be incorporated herein by reference, the definition consistent with this specification shall prevail.

Claims (38)

CLAIMS 1. A method of treating a well comprising: providing a treatment fluid comprising a base fluid and a blended cementitious component, wherein the blended cementitious component comprises kiln dust from two or more different sources; and The treatment fluid is introduced into the wellbore. 2. The method of claim 1, wherein the base fluid comprises water selected from the group consisting of fresh water, salt water, brine, and any combination thereof. 3. The method of claim 1, wherein the kiln dust is selected from the group consisting of lime kiln dust, cement kiln dust and combinations thereof. 4. The method of claim 1, wherein the kiln dust comprises cement kiln dust in the range of about 0.01% to 100% by weight based on the weight of the blended cement-based component amount present in the treatment solution. 5. The method of claim 1, wherein the treatment fluid is substantially free of any additional cementitious components other than the blended cementitious components. 6. The method of claim 1, wherein the treatment fluid is used in the wellbore during drilling. 7. The method of claim 1, wherein the treatment fluid is used in the wellbore in a well completion. 8. The method of claim 1, wherein the treatment fluid is used in the well bore in well stimulation. 9. The method of claim 1, wherein the amount of kiln dust from each of the two sources of the blended cement-based component is adjusted based on a parameter selected from the group consisting of: compressive strength, Young's modulus volume, fluid loss, thickening time, rheological values, free water and any combination thereof. 10. The method of claim 1, wherein the kiln dust comprises first kiln dust from a first source and second kiln dust from a second source, and wherein the method further comprises determining the first kiln dust Dust Reaction Index and Determination of the Second Kiln Dust Reaction Index. 11. The method of claim 10: wherein the step of determining said reactivity index of said first kiln dust uses the following equation: RI ₁ =MP ₁ /SSA ₁ wherein RI ₁ is said Reactivity Index of said first kiln dust, MP ₁ is a measured parameter of said first kiln dust, and SSA ₁ is the specific surface area of said first kiln dust; and wherein the step of determining said reactivity index of said second kiln dust uses the following equation: RI ₂ =MP ₂ /SSA ₂ Where RI ₂ is the Reactivity Index of the second kiln dust, MP ₂ is a measured parameter of the second kiln dust, and SSA ₂ is the specific surface area of the second kiln dust. 12. The method of claim 11, wherein the measured parameter is compressive strength, Young's modulus, fluid loss, thickening time, rheological value, free water, or any combination thereof. 13. The method of claim 12, wherein the properties of the blended cementitious components are optimized using the following equation: EP _Blend = (RI ₁ )(SSA ₁ )(f ₁ ) ^m + (RI ₂ )(SSA ₂ )(f ₂ ) ^m wherein EP is an estimated parameter of said blended cement-based component, f is the mass fraction of _first kiln dust, _f is the mass fraction of said second kiln dust, and m is a number from 1 to 10, And wherein said optimizing comprises adjusting f ₁ and/or f ₂ . 14. A method of cementing, comprising: providing a settable composition comprising water and a blended cementitious component, wherein the blended cementitious component comprises kiln dust from two or more different sources; and The settable composition is allowed to set to form a hardened mass. 15. The method of claim 14, wherein the kiln dust is selected from the group consisting of lime kiln dust, cement kiln dust and combinations thereof. 16. The method of claim 14, wherein the kiln dust comprises cement kiln dust in the range of about 0.01% to 100% by weight based on the weight of the blended cement-based component present in the settable composition. 17. The method of claim 14, wherein the settable composition is substantially free of any additional cementitious components other than the blended cementitious components. 18. The method of claim 14, wherein the amount of kiln dust from each of the two sources in the blended cementitious component is adjusted based on a parameter selected from the group consisting of: compression Strength, Young's modulus, fluid loss, thickening time, rheological values, free water and any combination thereof. 19. The method of claim 14, wherein the amount of kiln dust from each of the two sources in the blended cement-based component is adjusted to adjust the compressive strength. 20. The method of claim 14, wherein the kiln dust comprises first kiln dust from a first source and second kiln dust from a second source. 21. The method of claim 20, further comprising adjusting the particle size of the first kiln dust and/or the second kiln dust to adjust the compressive strength of the settable composition. 22. A method according to claim 20, wherein the particle size of the first kiln dust and/or the second kiln dust has been reduced by means of grinding to adjust the compressive strength of the settable composition. 23. The method of claim 20, wherein the reactivity index of the first kiln dust varies from the reactivity index of the second kiln dust by a factor of at least about 2:1. 24. The method of claim 20, wherein the reactivity index of the first kiln dust varies with the reactivity index of the second kiln dust by a factor of at least about 100:1. 25. The method of claim 20, wherein the first kiln dust has a different reactivity index than the second kiln dust. 26. The method of claim 20, further comprising determining a reactivity index of the first kiln dust and determining a reactivity index of the second kiln dust. 27. The method of claim 26: wherein the step of determining said reactivity index of said first kiln dust uses the following equation: RI ₁ =MP ₁ /SSA ₁ wherein RI is the Reactivity Index of the _first kiln dust, MP is _a measured parameter of the _first kiln dust, and SSA is the specific surface area of the first kiln dust, and wherein the step of determining said reactivity index of said second kiln dust uses the following equation: RI ₂ =MP ₂ /SSA ₂ Where RI ₂ is the Reactivity Index of the second kiln dust, MP ₂ is a measured parameter of the second kiln dust, and SSA ₂ is the specific surface area of the second kiln dust. 28. The method of claim 27, wherein the measured parameter is compressive strength, Young's modulus, fluid loss, thickening time, rheological value, free water, or any combination thereof. 29. The method of claim 27, wherein the properties of the blended cementitious components are optimized using the following equation: EP _Blend = (RI ₁ )(SSA ₁ )(f ₁ ) ^m + (RI ₂ )(SSA ₂ )(f ₂ ) ^m where EP is an estimated parameter of the blended cement-based component, f is the mass fraction of the _first kiln dust, _f is the mass fraction of the second kiln dust, and m is a value from 1 to 10, And wherein said optimizing comprises adjusting f ₁ and/or f ₂ . 30. The method of claim 14, further comprising placing the settable composition into a formation penetrated by a wellbore. 31. The method of claim 30, wherein the settable composition is applied in the wellbore in one cementing. 32. The method of claim 30, wherein the settable composition is used in the wellbore in refill cementing. 33. A method of cementing, comprising: There is provided a settable composition comprising water and an admixed cement-based component, wherein the admixed cement-based component comprises kiln dust and an additional cement-based component, the kiln dust and the additional cement-based component each with a defined response index; and The settable composition is allowed to set to form a hardened mass. 34. A method according to claim 33, wherein the settable composition comprises one or more of the features defined in claim 15 or claim 16. 35. A method of preparing a blended cementitious component comprising: providing a first kiln dust from a first source; providing a second kiln dust from a second source; and Blending at least the first kiln dust and the second kiln dust to form the blended cementitious component. 36. A method of measuring the reactivity of kiln dust comprising: measuring a parameter of the kiln dust, the kiln dust having a specific surface area; and The measured parameter is divided by the specific surface area of the kiln dust to obtain a reactivity index of the kiln dust. 37. A well treatment fluid comprising: base fluid; and A blended cementitious component comprising kiln dust from two or more different sources. 38. A well treatment fluid according to claim 37 comprising one or more of the features defined in any one of claims 1 to 5.