ADAPTATION OF THE TEMPERATURE SENSITIVITY OF THE CEMENT GROUT THICKENING TIME

Abstract

A method for designing a cement slurry comprising: (a) selecting at least one cement and a concentration thereof, water and a concentration thereof, and one or more chemical additives and a concentration thereof, such that a cement slurry is formed from the cement, the one or more chemical additives, and the water, meeting a density requirement; (b) calculating a thickening time of the cement slurry at wellbore temperature using a thickening-time model;(c) comparing the thickening time of the cement slurry with a thickening time requirement and performing steps (a)-(c) if the thickening time of the cement slurry does not meet or exceeds the thickening time requirement, wherein the selection step comprises selecting different concentrations and / or different chemical identities for the cement and / or one or more chemical admixtures than those previously selected, or performing step (d) if the thickening time of the cement slurry meets or exceeds the thickening time requirement; and (d) preparing the cement slurry.

Description

ADAPTATION OF TEMPERATURE SENSITIVITY OVER TIME THICKENING OF THE CEMENT GROUT BACKGROUND OF THE INVENTION Cement compositions are commonly used in well cementing, as well as in well construction and remedial cementing. Cement slurries can be used in a variety of underground applications. For example, in underground well construction, a pipe string (e.g., casing, short casing, expandable tubulars, etc.) can be run into a well and cemented in place. The process of cementing the pipe string in place is commonly called primary cementing. In a typical primary cementing method, a cement slurry can be pumped into an annulus between the well walls and the outer surface of the pipe string inside.Cement slurry can set in the annular space, forming a substantially impermeable, hardened cement annular sheath (i.e., a cement sleeve) that can support and position the pipe string in the well and bond the pipe string's outer surface to the underground formation. Among other things, the cement sleeve surrounding the pipe string prevents fluid migration in the annulus and protects the pipe string from corrosion. Cement slurries can also be used in corrective cementing methods, for example, to seal cracks or holes in pipe strings or cement sleeves, to seal highly permeable formation zones or fractures, to place a cement plug, and for similar applications. A particular challenge in well cementing is achieving a satisfactory thickening time in a cement slurry within a reasonable timeframe after placement in the underground formation. Often, several cement slurries with various additives are evaluated to determine if they meet the material engineering requirements for a specific well. The process of selecting cement slurry components is typically a best-estimate approach, using previous slurries and modifying them until a satisfactory solution is reached. This process can be time-consuming, and the resulting slurry can be complex. Furthermore, the cement components available in any given region may vary from those in another region, further complicating the selection process. BRIEF DESCRIPTION OF THE DRAWINGS These drawings illustrate certain aspects of some of the ways in which this disclosure is made and should not be used to limit or define the disclosure. Fig. 1 illustrates a method for designing a thickening time. Fig. 2 illustrates the introduction of a cement slurry into a well. DETAILED DESCRIPTION OF THE INVENTION This disclosure may generally refer to cementing methods and systems. More specifically, the embodiments may refer to the design of cement slurries at least partially based on a thickening time model. Cement slurries may contain cement, complementary cementitious admixtures, inert materials, and chemical additives. A cement slurry for use in well cementing is typically mixed in the well drilling zone with cement mixing equipment and pumped into the well using cement pumps. After mixing, there is a time lag between when the cement is in a liquid state and when it begins to set. As the cement slurry begins to set, it gradually becomes more viscous until it is fully set. There may be an upper viscosity limit beyond which the cement slurry becomes too viscous to pump. Generally, the upper viscosity limit is defined as the point at which the fluid has a consistency greater than 70 Bearden Consistency Units (Be).However, there may be other considerations where the cement slurry would be considered unpumpable, and therefore a Be value of 30, 50, 70, 100, or any other value may be selected as unpumpable. To determine the consistency or Be value of a cement slurry, a pressurized consistometer may be used in accordance with the procedure for determining cement thickening times established in API Practice RP 10B-2, Recommended Practice for Testing Well Cements, First Edition, July 2005. The time to reach the selected Bearden consistency units is reported as the thickening time.It is often a design criterion for a cement slurry to have a sufficiently long thickening time so that there is enough time to pump the required volume of cement into the well, but without having an excessively long thickening time that results in undue downtime while waiting for the cement to set. The thickening time of a cement slurry can be a function of pressure, temperature, cement slurry density, and cement slurry composition. Thickening time is an important characteristic of well cement designs and can influence the success of the cementing job or the need for remedial cementing operations. One factor that influences thickening time is temperature, which is not usually a constant value when cementing in wells. Often, a well's temperature profile varies with the downhole position; however, the current practice for determining thickening times is to use a high-pressure, high-temperature (HPHT) consistometer and apply a linear ascending temperature profile starting at ambient temperature and progressing to the circulating bottomhole temperature (BHCT). Using the consistometer method for thickening time yields a single thickening time value. However, in reality, the cement slurry will exhibit a range of thickening times.For example, the first barrel of cement pumped into the well may have a different thickening time compared to the last barrel pumped, depending on the temperature profile experienced by each barrel. This uncertainty in thickening time results in cement slurries with relatively high safety margins, and the thickening time may exceed the expected placement time. A second aspect of thickening time design is that downhole temperature can vary. This variation can be due to limitations in downhole measurement, mud circulation before the cementing job, losses, or the complete absence of measurement. In such situations, it is safe to select a cement composition that is less sensitive to changes in downhole temperature. A thermally robust composition is even more crucial in high-temperature wells. Such a robust composition will minimize the need for last-minute adjustments to additives or the risk of large variations in thickening time due to disturbances in quantity measurement. Designing a cement slurry to have a desired thickening time is an inefficient trial-and-error process that often requires multiple iterations of selecting slurry components and their mass fractions, and evaluating a thickening time for a slurry formed from those components. Small changes in composition can result in highly variable thickening times, caused by the fact that cementitious materials vary across different geographical areas. Therefore, a cement recipe prepared in one region may have a different thickening time than the same recipe prepared in a different region due to differences in the mineralogy and manufacturing processes of the cement components.Differences in thickening times can be difficult to predict, as the thickening time of a cement slurry is a complex function of several interacting factors. Cements are typically mixed in bulk plants, where cement and complementary cementitious materials and / or inert materials are blended in predetermined proportions to form a cement slurry. This cement slurry can then be transported to a well site and mixed with water to form cement grout, which can then be placed in a desired location to set and harden. Chemical additives may also be included in the bulk mix to form the cement slurry. These chemicals may include accelerators, retarders, fluid loss control additives, lost circulation control additives, rheology modifiers, and other chemical additives to impart desirable properties to the cement grout, such as fluid loss control, rheology, stability, and thickening time.The additive package that can meet all these properties is typically determined through an iterative process. This is because an additive used to meet one property can affect another. For example, a fluid loss control additive can retard cement slurry. Therefore, when designing the thickening time, the effects of each additive on the thickening time must be considered. The thickening time of a cement slurry can be written as a mathematical function of various factors, as shown in equation 1. Equation 1 Where TT is the thickening time, Tdh is a bottomhole temperature profile, is a pressure in the well, is the density of the cement slurry, is the composition of the cement slurry, and [A] is a concentration of the additive such as retarder / accelerator required. The model in equation 1 can be generalized to represent different temperature-time behaviors as shown in equation 2. Equation 2 'fdtcω. ω. w Where the thickening time is a function of time (t), Tk(t) is a bottomhole temperature as a function of time, is a well pressure as a function of time, p3(t) is the density of the cement slurry as a function of time, is the composition of the cement slurry as a function of time, and [A](t) is the concentration of the required retarder / accelerator as a function of time. The thickening time of the cement slurry can be found as a solution to the integral equation. Equation 2 allows the evaluation of the time-dependent effect of temperature on the thickening time. DOoU Equation 2 can also be generalized by assuming that the density and composition, including additives, of the cement slurry remain constant over time, which produces equation 3. Equation 3 ooou1Jedt As mentioned earlier, thickening time can depend on temperature. A relationship between temperature and thickening time can be described by the activation energy of the materials included in the cement slurry. This relationship can be generalized as shown in Equation 4. Equation 4 f-Ei1 1 TT — TTÍ exp ----lb H\ ñ Γ Where TTo is the characteristic thickening time of the cement mixture at a reference temperature Tref, E is the effective activation energy, R is the universal gas constant, and T is the bottomhole temperature. In some examples, T may be a function of time as T(t). TTo of the cement mixture is the thickening time of a cement mixture that includes cement, supplementary cementitious materials, if present, and additives, mixed with water to form a cement slurry at a reference density, and measured at a reference temperature. The effective activation energy in Equation 4 can determine the sensitivity of the cement design to temperature changes. For cements, E is a positive number indicating an increase in the reaction rate as the temperature increases. A relatively larger value of E indicates a relatively greater sensitivity to temperature changes. E is a material property that depends on the components of the cement slurry. A model of E is shown in Equation 5, where Ei(T) is the activation energy of the i-th individual component of the dry mix as a function of temperature, m is the mass, volume, or mole fraction of the i-th individual component of the dry mix, w is the water content of the cement slurry per mass of dry mix, and Ew is the activation energy associated with the amount of water in the slurry.In some cement slurries, the activation energy associated with the slurry can depend on the amount of water in the slurry. For example, the activation energy of a 14 ppg (pounds per gallon) (1677 kg / m³) slurry may be different from that of a 12 ppg (1438 kg / m³) slurry. One way to determine Ew is to measure the thickening time of the two slurries at different temperatures, comparing the activation energy of the 14 ppg (1677 kg / m³) and 12 ppg (1438 kg / m³) slurries. Ew can then be determined using Equation 6, if the water content of the mix materials is known. In equation 6, the dry mix referred to includes all components of a cement slurry other than water, such as cement, complementary cementitious admixtures, inert materials, and chemical additives. In some examples, the effective activation energy may have the form of equation 6.In equation 6, E¡(T) is the activation energy of the i-th individual component of the dry mix as a function of temperature, m¡ is the mass, volume or mole fraction of the i-th individual component of the dry mix, w is the water content of the cement slurry per mass of dry mix and Ewes is an activation energy associated with water. Equation 5 Equation 6Γ_Σ:Γτμ!:-Ε;:τ;Γ Σ; JR·;—W In general, the activation energy of component i can be a function of temperature, as shown in Equation 7. In Equation 7, f can be any polynomial or transcendental function, such as a power law, exponential, logarithmic, trigonometric, or any combination thereof. Equation 8 is a form of Equation 7 with a polynomial function where Eo, Ei, E2, etc., are constants and T is temperature. Equation 7 Et- / !(T) Equation 8 E; = Ec~Eit ~ E2T~---Some cement components can be relatively more sensitive to temperature changes. Table 1 illustrates E / R values ​​for selected cement components. Table 2 illustrates two cement compositions, and Table 3 illustrates thickening times for the cement compositions in Table 2 as measured on a consistometer. It can be observed that the inclusion of CKD makes the cement composition more sensitive to temperature changes. Table 1 Class / category E material mixture a / R (J / Mol-K) Portland 7 7 Cement Class H 95 Portland Cement Class G 359 1 fly ash Class F 378 1 fly ash Class C 837 1 volcanic ash N / A 316 2 CKD N / A 706 5 Table 2 IVIA / a / ZUZZ / UI ooou Material 1 2 Classes H .333 .333 Class C fly ash .333 .333 Volcanic ash .334 CKD .334 Table 3 Design temperature Thickening time at 210°F Thickening time at 120°F 146 290 126 402 In this example, CKD designs can be used in wells with varying temperatures without significantly changing the additives. Alternatively, CKD designs can lead to excessive cement waiting time or premature setting due to uncertainty regarding downhole temperatures. Therefore, knowledge of the temperature sensitivity of materials can be used for effective design at any temperature. Figure 1 illustrates a method 100 for using the thickening time models discussed earlier. Method 100 can begin at stage 102, where the availability of bulk materials, such as cement, complementary cementitious materials, and available cementitious admixtures, can be defined. The availability of bulk materials is generally location-dependent, with some geographic locations having access to bulk materials that others do not. Furthermore, bulk materials, such as mined materials and cement, can vary across geographic locations due to differences in raw materials and manufacturing methods, as well as natural variations among the deposits of extractable minerals in different geographic locations.In step 102, engineering parameters such as fluid loss control requirements, rheology requirements, stability requirements, and thickening time requirements, as well as density and temperature, are defined. After defining the available materials and engineering parameters, Method 100 can proceed to step 104. In step 104, a proposed cement composition can be selected, which may include cement components and their mass fractions, water and its mass fraction, and chemical admixtures and their mass fractions. The selection of chemical admixtures and their mass fractions may be, at least partially, based on fluid loss control, rheology, and stability. The cement components may include any of a cement, a complementary cementitious admixture, an inert material, and / or a chemical admixture that is available as defined in step 102.In step 106, the thickening time of the proposed cement composition can be calculated using any of the thickening time models mentioned above. For example, equations 22-24 or any other model derived from the equations disclosed herein can be used. In examples where cement components are selected in step 104 for which a power or other model variable is unknown, the unknown value can be calculated in step 108 using any of the methods mentioned above. From step 106, method 100 can proceed to step 10, where the thickening time calculated in step 106 can be compared with the required thickening time defined in step 102.If the calculated thickening time is not within the tolerance of the required thickening time, method 100 can return to step 104, where a second proposed cement composition can be selected which may include various cement components and / or various mass fractions of these and / or. IVIA / a / ZUZZ / UI ooou chemical additives and components thereof. If the calculated thickening time is within the tolerance of the required thickening time, method 100 may proceed to step 112. In step 112, the proposed cement composition may be prepared and the thickening time measured to verify that the cement composition has the required thickening time. The cement compositions described herein may generally include a hydraulic cement and water. A variety of hydraulic cements may be used in accordance with this disclosure, including, but not limited to, those comprising calcium, aluminum, silicon, oxygen, iron, and / or sulfur, which set and harden by reaction with water. Suitable hydraulic cements may include, but are not limited to, Portland cements, pozzolan cements, gypsum cements, high-alumina cements, silica cements, and any combination thereof. In certain examples, the hydraulic cement may include a Portland cement. In some examples, the Portland cements may include Portland cements that are classified as Class A, C, H, and G cements according to the American Petroleum Institute (API) Specification for Materials and Testing for Well Cements, API Specification 10, 5th ed., July 1, 1990.In addition, hydraulic cements may include cements classified by the American Society for Testing and Materials (ASTM) in C150 (Standard Specification for Portland Cement), C595 (Standard Specification for Blended Hydraulic Cements), or C1157 (Standard Specification for Hydraulic Cements), such as cements classified as ASTM Type I, II, or III. Hydraulic cement may be included in cement compositions in any amount suitable for a particular mix design. Among others, hydraulic cement may be included in cement compositions in an amount ranging from approximately 10% to approximately 80% by weight of the dry mix.For example, hydraulic cement may be present in an amount that varies between and / or includes any of about 10%, about 15%, about 20%, about 25%, about 30%, about 35%, about 40%, about 45%, about 50%, about 55%, about 60%, about 65%, about 70%, about 75% or about 80% by weight of cement compositions. Water can come from any source as long as it does not contain an excess of compounds that could adversely affect other components of the cement composition. For example, a cement composition may include fresh water or salt water. Salt water typically contains one or more dissolved salts and can be saturated or unsaturated as required for a particular application. Seawater or brines may be suitable for use in some applications. Furthermore, water may be present in a sufficient quantity to form a pumpable slurry. In certain cases, water may be present in the cement composition in an amount ranging from approximately 33% to approximately 200% by weight of the cementitious materials.For example, water cement may be present in an amount that varies between and / or includes any of approximately 33%, approximately 50%, approximately 75%, approximately 100%, approximately 125%, approximately 150%, approximately 175%, or approximately 200% by weight of the cementitious materials. The cementitious materials referred to may include all components that contribute to the compressive strength of the cement composition, such as hydraulic cement and complementary cementitious materials, for example. As mentioned previously, cement compositions may include supplementary cementitious materials. A supplementary cementitious material can be any material that contributes to the compressive strength of the cement composition. Some examples of supplementary cementitious materials include, but are not limited to, fly ash, blast furnace slag, silica fume, pozzolans, kiln dust, and clays. Although only some supplementary cementitious materials are disclosed herein, a person of average skill, with the benefit of this disclosure, should be able to readily recognize whether a material might be suitable for inclusion in a cement composition as a supplementary cementitious material. The composition of cement may include kiln dust as a supplementary cementitious material. Kiln dust, as that term is used herein, refers to a solid material generated as a byproduct of heating certain materials in kilns. The term kiln dust, as used herein, is intended to include kiln dust produced as described herein and equivalent forms of kiln dust. Depending on its source, kiln dust may exhibit cementitious properties, as it can set and harden in the presence of water. Examples of suitable kiln dust include cement kiln dust, lime kiln dust, and combinations thereof. Cement kiln dust may be generated as a byproduct of cement production that is removed from the gas stream and collected, for example, in a dust collector.Large quantities of cement kiln dust are typically collected during cement production and are commonly discarded as waste. The chemical analysis of cement kiln dust from various cement manufacturers varies depending on several factors, including the specific kiln feed, the efficiency of the cement production operation, and the associated dust collection systems. Cement kiln dust can generally include a variety of oxides, such as SiO₂, Al₂O₃, P₂O₃, CaO, MgO, SO₃, Na₂O, and K₂O. The chemical analysis of lime kiln dust from various lime manufacturers also varies depending on several factors, including the specific limestone or dolomitic limestone feed, the type of kiln, the kiln operating mode, the efficiency of the lime production operation, and the associated dust collection systems.Lime kiln dust typically includes varying amounts of free lime and magnesium, free limestone and / or dolomitic limestone, and a variety of oxides, such as SiC, Al₂O₃, Fe₂U₃, CaO, MgO, SO₃, Na₂U, and K₂O, as well as other components, such as chlorides. Cement kiln dust may be added to the cement composition before, concurrently with, or after activation. Cement kiln dust may also include partially calcined kiln feed that is removed from the gas stream and collected in a dust collector during cement manufacturing. The chemical analysis of CKD from various cement manufacturers varies depending on numerous factors, including the specific kiln feed, the efficiency of the cement production operation, and the associated dust collection systems. CKD can generally comprise a variety of oxides, such as SiC2, Al2O3, Fe2Os, CaO, MgO, SO3, Na2O and K2O.CKD and / or lime kiln dust may be included in examples of cement composition in an amount suitable for a particular application. In some examples, the cement composition may also include one or more of slag, natural glass, shale, amorphous silica, or metakaolin as a supplementary cementitious material. Slag is generally a granulated blast furnace byproduct of pig iron production, containing the oxidized impurities found in iron ore. Cement may also include shale. A variety of shales may be suitable, including those containing silicon, aluminum, calcium, and / or magnesium. Examples of suitable shales include vitrified shale and / or calcined shale. In some examples, the cement composition may also include amorphous silica as a supplementary cementitious material. Amorphous silica is a powder that may be included in the cement embodiment to increase its compressive strength.Amorphous silica is generally a byproduct of a ferrosilicon production process, where amorphous silica can be formed by the oxidation and condensation of gaseous silicon suboxide, SiO, which is formed as an intermediate during the process. In some examples, the cement composition may also include a variety of fly ash as a supplementary cementitious material, which may include fly ash classified as Class C, Class F, or Class N according to the American Petroleum Institute (API) Specification for Materials and Testing for Well Cements, API Specification 10, 5th ed., July 1, 1990. In some examples, the cement composition may also include zeolites as supplementary cementitious materials. Zeolites are generally porous aluminosilicate minerals that can be natural or synthetic. Synthetic zeolites are based on the same type of structural cell as natural zeolites and may comprise DOOU aluminosilicate hydrates. As used herein, the term zeolite refers to all natural and synthetic forms of zeolite. When used, one or more of the supplementary cementitious materials mentioned above may be present in the cement composition. For example, among others, one or more supplementary cementitious materials may be present in an amount ranging from approximately 0.1% to approximately 80% by weight of the cement composition. Specifically, the supplementary cementitious materials may be present in an amount that varies between and / or includes any of approximately 0.1%, approximately 10%, approximately 20%, approximately 30%, approximately 40%, approximately 50%, approximately 60%, approximately 70%, or approximately 80% by weight of the cement. In some examples, the cement composition may also include hydrated lime. As used herein, the term hydrated lime shall be understood to mean calcium hydroxide. In some embodiments, hydrated lime may be provided as quicklime (calcium oxide) which hydrates when mixed with water to form hydrated lime. Hydrated lime may be included in the cement composition examples, for instance, to form a hydraulic composition with the complementary cementitious components. For example, hydrated lime may be included in a weight ratio of complementary cementitious material to hydrated lime of approximately 10:1 to approximately 1:1 or from 3:1 to approximately 5:1. When present, hydrated lime may be included in the set cement composition in an amount in the range of approximately 10% to approximately 100% by weight of the cement composition, for example.In some examples, hydrated lime may be present in an amount that varies between and / or includes any of approximately 10%, approximately 20%, approximately 40%, approximately 60%, approximately 80%, or approximately 100% by weight of the cement composition. In some examples, the cementitious components present in the cement composition may consist essentially of one or more complementary cementitious materials and hydrated lime. For example, the cementitious components may comprise primarily the complementary cementitious materials and hydrated lime without any additional components (e.g., Portland cement, fly ash, slag cement) that set hydraulically in the presence of water. Lime can be present in cement compositions in various ways, including as calcium oxide and / or calcium hydroxide, or as a reaction product, such as when Portland cement reacts with water. Alternatively, lime can be included in the cement composition based on the amount of silica in the cement composition. A cement composition can be designed to have a target weight ratio of lime to silica. The target lime-to-silica ratio can be a IVIA / a / ZUZZ / UI ODOU molar ratio, molal ratio, or any other equivalent form for expressing a relative amount of silica with respect to lime. Any suitable target weight ratio of lime to silica may be selected, including from about 10 / 90 lime to silica by weight to about 40 / 60 lime to silica by weight. Alternatively, from about 10 / 90 lime to silica by weight to about 20 / 80 lime to silica by weight, from about 20 / 80 lime to silica by weight to about 30 / 70 lime to silica by weight, or from about 30 / 70 lime to silica by weight to about 40 / 63 lime to silica by weight. Other additives suitable for use in underground cementing operations may also be included in embodiments of the cement composition. Examples of such additives include, but are not limited to: weighting agents, lightweight additives, gas-generating additives, mechanical property enhancers, lost circulation materials, seepage control additives, fluid loss control additives, antifoaming agents, foaming agents, thixotropic additives, and combinations thereof. In some embodiments, one or more of these additives may be added to the cement composition after storage but before placement in an underground formation. In some examples, the cement composition may also include a dispersant.Examples of suitable dispersants include, but are not limited to, sulfonated formaldehyde-based dispersants (e.g., sulfonated acetone formaldehyde condensate) or polycarboxylated ether dispersants. In some examples, the dispersant may be included in the cement composition in an amount ranging from approximately 0.01% to approximately 5% by weight of the cementitious materials. In specific examples, the dispersant may be present in an amount that varies between and / or includes any of approximately 0.01%, approximately 0.1%, approximately 0.5%, approximately 1%, approximately 2%, approximately 3%, approximately 4%, or approximately 5% by weight of the cementitious materials. In some examples, the cement composition may also include a setting retarder. A wide variety of setting retarders may be suitable for use in cement compositions. For example, the setting retarder may comprise phosphonic acids, such as ethylenediaminetetra(methylenephosphonic acid), diethylenetriaminepenta(methylenephosphonic acid), etc.; lignosulfonates, such as sodium lignosulfonate, calcium lignosulfonate, etc.; salts such as stannous sulfate, lead acetate, monobasic calcium phosphate; organic acids, such as citric acid, tartaric acid, etc.; cellulose derivatives such as hydroxyethylcellulose (HEC) and carboxymethylhydroxyethylcellulose (CMHEC); synthetic copolymers or terpolymers comprising sulfonate and carboxylic acid groups, such as sulfonate-functionalized acrylamide-acrylic acid copolymers; and borate compounds. IVIA / a / ZUZZ / UI DOoU such as alkali borates, sodium metaborate, sodium tetraborate, potassium pentaborate; derivatives thereof, or mixtures thereof. Examples of suitable setting retarders include, but are not limited to, phosphonic acid derivatives. Generally, the setting retarder may be present in the cement composition in a quantity sufficient to delay setting for a desired time. In some examples, the setting retarder may be present in the cement composition in an amount ranging from about 0.01% to about 10% by weight of the cementitious materials. In specific examples, the setting retarder may be present in an amount that varies between and / or includes any of about 0.01%, about 0.1%, about 1%, about 2%, about 4%, about 6%, about 8%, or about 10% by weight of the cementitious materials. In some examples, the cement composition may also include an accelerator. A wide variety of accelerators may be suitable for use in cement compositions. For example, the accelerator may include, but is not limited to, aluminum sulfate, alum, calcium chloride, calcium nitrate, calcium nitrite, calcium formate, calcium sulfoaluminate, calcium sulfate, gypsum hemihydrate, sodium aluminal, sodium carbonate, sodium chloride, sodium silicate, sodium sulfate, ferric chloride, or a combination thereof. In some examples, the accelerator may be present in the cement composition in an amount ranging from approximately 0.01% to approximately 10% by weight of the cementitious materials. In specific examples, the accelerator may be present in an amount that varies between approximately 0.01% and / or includes approximately 0.01%.1%, about 1%, about 2%, about 4%, about 6%, about 8% or about 10% by weight of cementitious materials. Cement compositions generally need to have a density suitable for a particular application. For example, a cement composition might have a density in the range of about 8 pounds per gallon (ppg) (959 kg / m³) to about 20 ppg (2397 kg / m³), or from about 8 ppg to about 12 ppg (1437 kg / m³), or from about 12 ppg to about 16 ppg (1917.22 kg / m³), or from about 16 ppg to about 20 ppg, or any range in between. Examples of cement compositions may be foamed or unfoamed, or may include other means of reducing their density, such as hollow microspheres, low-density elastic microspheres, or other density-reducing admixtures known in the art. The cement slurries disclosed herein can be used in a variety of underground applications, including corrective and primary cementing. The cement slurries can be introduced into an underground formation and allowed to set. In primary cementing applications, for example, the cement slurries can be introduced into the annular space between a pipe located in a well and the DOoU (Double Outer Hole) cement compositions are placed in the wellbore walls (and / or a larger conduit in the wellbore) where the well penetrates the underground formation. The cement slurry can be allowed to set in the annular space to form a hardened cement annular sleeve. The cement slurry can form a barrier that prevents fluid migration in the wellbore. The cement composition can also, for example, support the conduit in the wellbore. In corrective cementing applications, cement compositions can be used, for example, in compression cementing operations or in the placement of cement plugs. For example, cement compositions can be placed in a wellbore to plug an opening (e.g., a void or crack) in the formation, in a gravel pack, in the conduit, in the cement sleeve, and / or between the cement sleeve and the conduit (e.g., a micro-annulus). Reference is now made to Fig. 2, which illustrates the use of a cement slurry 200. The cement slurry 200 may comprise any of the components described herein. The cement slurry 200 may be designed, for example, using the thickening-time models described herein. The cement slurry 200 may be placed in a subsurface formation 205 according to example systems, methods, and cement slurries. As illustrated, a well 210 may be drilled into the subsurface formation 205. While the well 210 is shown as generally extending vertically into the subsurface formation 205, the principles described herein may also be applied to wells that extend at an angle through the subsurface formation 205, such as horizontal and inclined wells. As illustrated, the well 210 comprises walls 215.In the illustration, casing 230 can be cemented to the walls 215 of well 210 using a cement sleeve 220. In the illustration, one or more additional conduits (e.g., an intermediate casing, a production casing, short casings, etc.) shown here as casing 230 can also be arranged in well 210. As illustrated, a wellbore ring 235 is formed between casing 230 and the walls 215 of well 210. One or more centralizers 240 can be attached to casing 230, for example, to centralize casing 230 in well 210 before and during the cementing operation. Cement slurry 200 can be pumped into casing 230.Cement slurry 200 may be allowed to flow down the inside of casing 230 through the casing shoe 245 at the bottom of casing 230 and up around casing 230 in well ring 235. Cement slurry 200 may be allowed to set in well ring 235, for example, to form a cement sheath that supports and positions casing 230 in well 210. While not specified, other techniques may also be used for introducing cement slurry 200. For example, reverse circulation techniques may be used, which include introducing cement slurry 200 into the underground formation 205 through well ring 235 instead of through casing 230.As it is introduced, the cement slurry 200 may displace other fluids 250, such as drilling fluids and / or spacer fluids, that may be present inside the casing 230 and / or the wellbore ring 235. Although not illustrated, at least a portion of the displaced fluids 250 may escape from the wellbore ring 235 through a flow line and be deposited, for example, in one or more holding wells. A bottom plug 255 may be run into the well 210 before the cement slurry 200, for example, to separate the cement slurry 200 from any fluids 250 that may be inside the casing 230 before cementing. After the lower plug 255 reaches the coupling collar 280, a diaphragm or other suitable device must be broken to allow the cement grout 200 to pass through the lower plug 255. The lower plug 255 is shown in the coupling collar 280.In the illustration, a top plug 285 can be inserted into well 210 behind the cement slurry 200. The top plug 260 can separate the cement slurry 200 from a displacement fluid 265 and also push the cement slurry 200 through the bottom plug 255. The following statements may describe certain forms of disclosure, but should not be considered limiting to any particular form of disclosure. Declaration 1. A method for designing a cement slurry comprising: (a) selecting at least one cement and a concentration thereof, water and a concentration thereof, and one or more chemical additives and a concentration thereof, such that a cement slurry is formed from the cement, the one or more chemical additives, and the water, meeting a density requirement; (b) calculating a thickening time of the cement slurry at wellbore temperature using a thickening-time model;(c) comparing the thickening time of the cement slurry with a thickening time requirement and performing steps (a)-(c) if the thickening time of the cement slurry does not meet or exceeds the thickening time requirement, wherein the selection step comprises selecting different concentrations and / or different chemical identities for the cement and / or one or more chemical admixtures than those previously selected, or performing step (d) if the thickening time of the cement slurry meets or exceeds the thickening time requirement; and (d) preparing the cement slurry. Claim 2. The method according to claim 1, wherein the cement is selected from the group consisting of Portland cements, pozzolan cements, gypsum cements, high alumina cements, silica cements and combinations thereof. IVIA / a / ZUZZ / UI DOOU Declaration 3. The method according to claim 1, wherein the one or more chemical additives are selected from the group consisting of cement setting retarders, cement accelerators, and combinations thereof. Declaration 4. The method according to claim 1, wherein the thickening time model comprises the following equation: K ΓΓ - ΓΓΰexp 7) j where TT is the thickening time, TT0 is the characteristic thickening time, Tref is a reference temperature, E is the effective activation energy, R is the universal gas constant, and T is the temperature. Claim 5. The method according to claim 4, wherein T is a well temperature profile. Declaration 6. The method according to claim 4, wherein the activation energy comprises the following equation: E =u where E¡ is the activation energy of the i-th component of the cement grout with concentration m¡, w is the water content, and Ews is the activation energy associated with respect to water. Declaration 7. A method comprising: preparing a grout comprising a cement, a complementary cementitious material, water, and a chemical additive; measuring a thickening time of the grout; and calculating an activation energy of the chemical additive or the complementary cementitious material by using a thickening time model and the thickening time of the grout. Claim 8. The method according to claim 7, wherein the cement is selected from the group consisting of Portland cements, pozzolan cements, gypsum cements, high alumina cements, silica cements and combinations thereof. Claim 9. The method according to claim 7, wherein the supplementary cementitious material is selected from the group consisting of fly ash, blast furnace slag, silica fume, pozzolans, kiln dust, clays and combinations thereof, and the chemical additive is selected from the group consisting of cement setting retarders, cement accelerators and combinations thereof. Declaration 10. The method according to claim 7, wherein the thickening time model comprises the following equation TT — TTDexp --7) ) where TT is the thickening time, TTo is the characteristic thickening time, Tref is a reference temperature, E is the effective activation energy, R is the universal gas constant, and T is the temperature. Claim 11. The method according to claim 7, wherein T is a well temperature profile. Declaration 12. The method according to claim 7, wherein the effective activation energy comprises the following equation: E — where E¡ is the activation energy of the i-th component of the cement grout with concentration m¡, w is the water content, and Ewes is the activation energy associated with respect to water. Claim 13. The method according to claim 7 further comprising: (a) selecting at least one cement and a concentration thereof, water and a concentration thereof, and one or more chemical additives and a concentration thereof, such that a second cement slurry is formed from the cement, the one or more chemical additives, and the water, meeting a density requirement; (b) calculating a thickening time of the second cement slurry at well temperature using a thickening time model;(c) compare the thickening time of the second cement slurry with a thickening time requirement and perform steps (a)-(c) if the thickening time of the cement slurry does not meet or exceeds the thickening time requirement, wherein the selection step comprises selecting different concentrations and / or different chemical identities for the cement and / or one or more chemical admixtures than those previously selected, or perform step (d) if the thickening time of the cement slurry meets or exceeds the thickening time requirement; and (d) prepare the second cement slurry. Claim 14. The method according to claim 13, wherein the thickening time model comprises the following equation: (-E\fii \ \ —L·--- I (where TT is the thickening time, TTq is the characteristic thickening time, Tref is a reference temperature, E is the effective activation energy, R is the universal gas constant, and T is the temperature. Claim 15. The method according to claim 13, wherein T is a well temperature profile. Declaration 16. The method according to claim 13, wherein the activation energy comprises the following equation: E = where Ei is the —XV IVIA / a / ZUZZ / UI ooou activation energy of the i-th component of the cement grout with concentration mw is the water content, and Ewes is the activation energy associated with respect to water. DOoU Declaration 17. A method comprising: selecting, by use of a thickening time model, at least one cement and a concentration thereof, at least one complementary cementitious material and a concentration thereof, water and a concentration thereof, and a chemical admixture and a concentration thereof, such that a slurry is formed from the cement and a concentration thereof, the at least one complementary cementitious material and a concentration thereof, the water and a concentration thereof, and the chemical admixture and a concentration thereof, that meets or exceeds a thickening time requirement; and preparing the cement slurry. Claim 18. The method according to claim 17, wherein the thickening time model comprises the following equation: TT = TTeexp I -7-í-r--“II where TT is the thickening time, TTo is the characteristic thickening time, Tref is a reference temperature, E is the effective activation energy, R is the universal gas constant, and T is the temperature. Claim 19. The method according to claim 17, wherein T is a well temperature profile. Declaration 20. The method according to claim 17, wherein the activation energy comprises the following equation: E = £.es|aactivation energy of the i-th component of the cement grout with concentration m¡, w is the water content, and Ev. is the activation energy associated with respect to water. The cement compositions and associated methods disclosed may directly or indirectly affect any pumping system, including, but not limited to, any conduits, pipes, trucks, tubing, and / or tubing that may be coupled to the pump and / or any pumping systems and that may be used to fluidly transport the cement compositions to the bottom of the well; any pumps, compressors, or motors (e.g., at the top or bottom of the well) used to set the cement compositions in motion; any related valves or fittings used to regulate the pressure or flow rate of the cement compositions; and any sensors (i.e., pressure, temperature, flow rate, etc.), gauges, and / or combinations thereof, and the like. The cement compositions may also directly or indirectly affect any mixing hopper and holding pit and their variations. It should be understood that, while the compositions and methods are described in terms of comprising, containing, or including various components or steps, the compositions and methods may also essentially consist of or be composed of the various components and steps. Furthermore, the indefinite article "a" or "an," as used in the claims, means, according to its definition herein, one or more of the elements it introduces. For the sake of brevity, only certain ranges are explicitly disclosed herein. However, ranges from any lower bound may be combined with any upper bound to refer to a range not explicitly stated, and ranges from any lower bound may be combined with any other lower bound to refer to a range not explicitly stated; likewise, ranges from any upper bound may be combined with any other upper bound to refer to a range not explicitly stated. Furthermore, whenever a numerical range with a lower and upper bound is disclosed, any number and any included range within that range are specifically disclosed.In particular, it should be understood that each range of values ​​(of the form of approximately aa to approximately b, or equivalently, approximately aab, or equivalently, approximately ab) disclosed herein establishes each number and range encompassed within the broader range of values, even if not explicitly stated. Therefore, each individual point or value may serve as its own lower or upper bound, combined with any other individual point or value or any other lower or upper bound, to enumerate a range not explicitly stated. Therefore, this disclosure is tailored to achieve the stated purposes and advantages, as well as those inherent herein. The specific examples disclosed above are merely illustrative, as this disclosure may be modified and implemented in different but equivalent ways that are obvious to persons of a mid-level skill who benefit from its teachings. While individual examples are discussed, the disclosure covers all combinations thereof. Furthermore, it is not intended to limit the details of construction or design shown herein, except as described in the following claims. Additionally, the terms in the claims have their plain and ordinary meanings unless explicitly and clearly defined otherwise by the patent holder.Therefore, it is evident that the specific illustrative examples disclosed above may be altered or modified, and that all such variations are considered within the scope and spirit of this disclosure. If any conflict arises between the uses of a word or term in this specification and one or more patents or other documents that may be incorporated herein by reference, the definitions consistent with this specification shall be adopted.

Claims

1. A method for designing a cement slurry comprising: (a) selecting at least one cement and a concentration thereof, water and a concentration thereof, and one or more chemical additives and a concentration thereof, such that a cement slurry is formed from the cement, the one or more chemical additives, and the water, meeting a density requirement; (b) calculating a thickening time of the cement slurry at wellbore temperature using a thickening-time model;(c) comparing the thickening time of the cement slurry with a thickening time requirement and performing steps (a)-(c) if the thickening time of the cement slurry does not meet or exceeds the thickening time requirement, wherein the selection step comprises selecting different concentrations and / or different chemical identities for the cement and / or one or more chemical admixtures than those previously selected, or performing step (d) if the thickening time of the cement slurry meets or exceeds the thickening time requirement; and (d) preparing the cement slurry.

2. The method according to claim 1, wherein the cement is selected from the group consisting of Portland cements, pozzolan cements, gypsum cements, high alumina cements, silica cements and combinations thereof, and wherein one or more chemical additives are selected from the group consisting of cement setting retarders, cement accelerators and combinations thereof.

3. The method according to any of claims 1-2, wherein the thickening time model comprises the following equation: t - IXesp —---: \ fi \T..£ / · Tj where t is the thickening time, TTo is the characteristic thickening time, Tret is a reference temperature, E is the effective activation energy, R is the universal gas constant, and T is the temperature.

4. The method according to claim 3, wherein T is a well temperature profile.

5. The method according to claim 3, wherein the activation energy comprises the following equation: DOOU Σ-- ΕρΠ; ~Ev.W ¿,. m. — w where E¡ is the activation energy of the i-th component of the cement grout with concentration m¡, w is the water content, and is the activation energy associated with respect to water.

6. A method comprising: preparing a grout comprising a cement, a complementary cementitious material, water, and a chemical additive; measuring a thickening time of the grout; and calculating an activation energy of the chemical additive or the complementary cementitious material by using a thickening time model and the thickening time of the grout.

7. The method according to claim 6, wherein the cement is selected from the group consisting of Portland cements, pozzolan cements, gypsum cements, high alumina cements, silica cements and combinations thereof, and wherein the complementary cementitious material is selected from the group consisting of fly ash, blast furnace slag, silica fume, pozzolans, kiln dust, clays and combinations thereof, and the chemical additive is selected from the group consisting of cement setting retarders, cement accelerators and combinations thereof.

8. The method according to claim 6 further comprising: (a) selecting at least one cement and a concentration thereof, water and a concentration thereof, and one or more chemical additives and a concentration thereof, such that a second cement slurry is formed from the cement, the one or more chemical additives, and the water, meeting a density requirement; (b) calculating a thickening time of the second cement slurry at well temperature using a thickening time model;(c) comparing the thickening time of the second cement slurry with a thickening time requirement and performing steps (a)-(c) if the thickening time of the cement slurry does not meet or exceeds the thickening time requirement, wherein the selection step comprises selecting different concentrations and / or different chemical identities for the cement and / or one or more chemical admixtures than those previously selected if the thickening time of the cement slurry meets or exceeds the thickening time requirement; and (d) preparing the second cement slurry.

9. The method according to any of claims 6-8, wherein the thickening time model comprises the following equation: / —£7 1 TT = TTcexp ----0 T·) where TT is the thickening time, TT0 is the characteristic thickening time, Tret is a reference temperature, E is the effective activation energy, R is the universal gas constant, and T is the temperature.

10. The method according to claim 6, wherein T is a well temperature profile.

11. The method according to any of claims 6-8, wherein the activation energy comprises the following equation: K Fun.· E = :— where E¡ is the activation energy of the i-th component of the cement grout with concentration m¡, w is the water content, and £7 is the activation energy associated with respect to water.

12. A method comprising: selecting, by means of a thickening time model, at least one cement and a concentration thereof, at least one complementary cementitious material and a concentration thereof, water and a concentration thereof, and a chemical additive and a concentration thereof, such that a slurry is formed from the cement and a concentration thereof, the at least one complementary cementitious material and a concentration thereof, the water and a concentration thereof, and the chemical additive and a concentration thereof, that meets or exceeds a thickening time requirement; and preparing the cement slurry.

13. The method according to claim 12, wherein the thickening time model comprises the following equation: / —£7 1 TT = TILesp ----iβ Π R Tj) where TT is the thickening time, TTo is the characteristic thickening time, Tret is a reference temperature, E is the effective activation energy, R is the universal gas constant, and T is the temperature.

14. The method according to claim 12, wherein T is a well temperature profile. DOOU 15. The method according to claim 12, wherein the activation energy comprises the following equation: where Ei is the activation energy of the i-th component of the cement grout with concentration mi, w is the water content, and Ev is the activation energy associated with respect to water.

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