Method for backfilling and sealing a borehole with compositions containing cement kiln dust and pumicite

Description

BACKGROUND

[0001] The present invention relates to cementing operations and, more particularly, in certain embodiments, to plug-and-abandon operations using plugging compositions comprising cement kiln dust ("CKD"), pumicite, and / or lime.

[0002] In cementing methods, such as well construction and remedial cementing, sealant compositions are commonly utilized. As used herein, the term "sealant composition" refers to a composition(s) that hydraulically sets or otherwise develops compressive strength suitable for use in subterranean applications. One type of a sealant composition is a plugging composition that can be used in plug-and-abandon operations whereby a plug is formed in a well bore to seal off the well bore for abandonment. In performing plug-and-abandon operations, a plugging composition may be placed in the well bore at a desired depth. The plugging composition should set in the wellbore, forming a hardened mass (e.g., a plug) that seals off selected intervals of the well bore. The plug should prevent and / or reduce zonal communication and migration of fluids that may contaminate water-containing formations. It may be desirable in certain instances to form one or more plugs in the well bore adjacent to hydrocarbon-producing formations and water-containing formations.

[0003] Sealant compositions used heretofore may comprise Portland cement. Portland cement generally is a major component of the cost for the sealant compositions. To reduce the cost of such sealant compositions, other components may be included in the sealant composition to replace some of the Portland cement. Such components may include cement kiln dust ("CKD"), fly ash, slag cement, shale, metakaolin, zeolite, and the like. CKD is a partially calcined kiln feed which is removed from the gas stream and collected, for example, in a dust collector during the manufacture of cement. The term "CKD" is used herein to mean cement kiln dust made as described above and equivalent forms of cement kiln dust made in other ways.

[0004] US 2010 / 044043 discloses methods of cementing in subterranean formations using cement kiln dust in compositions having reduced Portland cement content. An embodiment of a method comprises placing a sealant composition that comprises cement kiln dust and is essentially free of Portland cement in a subterranean formation; and allowing the sealant composition to set.

[0005] US 2009 / 200029 discloses a method of cementing comprising: introducing a cement composition into a subterranean formation, wherein the cement composition comprises cement kiln dust, a natural pozzolan, and water; and allowing the cement composition to set.SUMMARY

[0006] The present invention relates to cementing operations and, more particularly, in certain embodiments, to plug-and-abandon operations using plugging compositions comprising CKD, pumicite, and / or lime.

[0007] A first aspect of the present invention is a well bore plug-and-abandon operation comprising placing a plugging composition in the well bore, the plugging composition consisting of: cement kiln dust in an amount of 25% to 75% by weight of cementitious components; pumicite in an amount of 25% to 75% by weight of cementitious components; hydrated lime in an amount of 5% to 10% by weight of cementitious components; up to 1% of Portland cement by weight of cementitious components; a set retarder in an amount of 0.4% to 1% by weight of cementitious components; water; a dispersant in an amount of 1 to 1.75% by weight of cementitious components; and optionally, at least one additive selected from the group consisting of fly ash, slag cement, metakaolin, shale, zeolite, crystalline silica, amorphous silica, fumed silica, salt, fiber, hydratable clay, microsphere, rice husk ash, elastomer, elastomeric particle, resin, latex, and any combination thereof; and allowing the plugging composition to set and form a plug.

[0008] Also disclosed is a method of plugging a well bore for abandonment comprising: placing a plugging composition in the well bore, the plugging composition comprising cement kiln dust in an amount of about 5% to about 100% by weight of cementitious components, pumicite in an amount of about 5% to about 100% by weight of cementitious components, 0% to about 24% of Portland cement by weight of cementitious components, and water; and allowing the plugging composition to set and form a plug.

[0009] Also disclosed is a method of plugging a well bore for abandonment comprising: placing a plugging composition in the well bore, the plugging composition comprising: a cementitious component consisting essentially of cement kiln dust, pumicite, and lime, and water; and allowing the plugging composition to set and form a plug.

[0010] Also disclosed is a plugging composition comprising: cement kiln dust in an amount of about 5% to about 100% by weight of cementitious components; pumicite in an amount of about 5% to about 100% by weight of cementitious components; 0% to about 24% of Portland cement by weight of cementitious components; and water.

[0011] 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 scope of the invention.DESCRIPTION OF PREFERRED EMBODIMENTS

[0012] The present invention relates to cementing operations and, more particularly, to plug-and-abandon operations using plugging compositions comprising CKD, pumicite, and hydrated lime. There may be several potential advantages to the methods and compositions of the present invention, only some of which may be alluded to herein. One of the many potential advantages of embodiments of the present invention is that the inclusion of the CKD and / or pumicite in the plugging composition may reduce the amount of, or potentially eliminate, a higher cost additive, such as Portland cement, resulting in a more economical plugging composition. Another potential advantage of embodiments of the present invention is that reduction of the amount of Portland cement should reduce the carbon footprint of the plug-and-abandon operation.

[0013] The plugging compositions of the present invention comprises CKD, pumicite, and water. The plugging compositions further comprise hydrated lime. Other optional additives may also be included in the plugging compositions of the present invention as desired, including, but not limited to, fly ash, slag cement, metakaolin, shale, zeolite, combinations thereof, and the like. As described in more detail herein, embodiments of the plugging compositions of the present invention may be foamed and / or extended as desired by those of ordinary skill in the art.

[0014] The plugging compositions of the present invention should have a density suitable for a particular application as desired by those of ordinary skill in the art, with the benefit of this disclosure. In some embodiments, the plugging compositions of the present invention may have a density in the range of from about 8 pounds per gallon ("ppg") [959 kg / m 3< ] to about 16 ppg [1917 kg / m 3< ]. In other embodiments, the plugging compositions may be foamed to a density in the range of from about 8 ppg [959 kg / m 3< ] to about 13 ppg [1558 kg / m 3< ].

[0015] The plugging compositions comprise CKD. During the manufacture of cement, a waste material commonly referred to as cement kiln dust ("CKD") is generated. Disposal of the waste CKD can add undesirable costs to the manufacture of the cement, as well as the environmental concerns associated with its disposal. The chemical analysis of CKD from various cement manufactures varies depending on a number of factors, including the particular kiln feed, the efficiencies of the cement production operation, and the associated dust collection systems. CKD generally may comprise a variety of oxides, such as SiO 2 , Al 2 O 3 , Fe 2 O 3 , CaO, MgO, SO 3 , Na 2 O, and K 2 O.

[0016] The CKD generally may exhibit cementitious properties, in that it may set and harden in the presence of water. In accordance with embodiments of the present invention, the CKD may be used, among other things, to replace higher cost cementitious components, such as Portland cement, resulting in more economical plugging compositions. In addition, substitution of the CKD for the Portland cement should result in a plugging composition with a reduced carbon footprint.

[0017] The CKD is included in the plugging compositions in an amount sufficient to provide the desired compressive strength, density, cost reduction, and / or reduced carbon footprint. The CKD is present in the plugging compositions of the present invention in an amount in the range of from about 25% to about 75% by weight of cementitious components. Cementitious components include those components or combinations of components of the plugging compositions that hydraulically set, or otherwise harden, to develop compressive strength, including, for example, CKD, fly ash, pumicite, slag, lime, shale, and the like. The CKD may be present, in certain embodiments, in an amount of about 25%, about 30%, about 35%, about 40%, about 45%, about 50%, about 55%, about 60%, about 65%, about 70%, or about 75%.One of ordinary skill in the art, with the benefit of this disclosure, will recognize the appropriate amount of CKD to include for a chosen application.

[0018] The plugging compositions further comprises pumicite. Generally, pumicite is a volcanic rock that exhibits cementitious properties, in that it may set and harden in the presence of hydrated lime and water. Hydrated lime is used in combination with the pumicite, for example, to provide sufficient calcium ions for pumicite to set. In accordance with the present invention, the pumicite is used, among other things, to replace higher cost cementitious components, such as Portland cement, resulting in more economical plugging compositions. As previously mentioned, replacement of the Portland cement should also result in a plugging composition with a reduced carbon footprint.

[0019] The pumicite is included in an amount sufficient to provide the desired compressive strength, density, cost reduction and / or reduced carbon footprint for a particular application. The pumicite is present in the plugging compositions of the present invention in an amount in the range of from about 25% to about 75% by weight of cementitious components. For example, the pumicite may be present in an amount of about 25%, about 30%, about 35%, about 40%, about 45%, about 50%, about 55%, about 60%, about 65%, about 70%, or about 75%. The pumicite is present in the plugging compositions of the present invention in an amount in the range of from about 25% to about 75% by weight of cementitious components. One of ordinary skill in the art, with the benefit of this disclosure, will recognize the appropriate amount of the natural pozzolan to include for a chosen application.

[0020] The water that is used in the plugging compositions include, for example, freshwater, saltwater (e.g., water containing one or more salts dissolved therein), brine (e.g., saturated saltwater produced from subterranean formations), seawater, or combinations thereof. Generally, the water may be from any source, provided that the water does not contain an excess of compounds that may undesirably affect other components in the plugging composition. In some embodiments, the water may be included in an amount sufficient to form a pumpable slurry. The water may be included in the plugging compositions of the present invention in an amount in the range of about 40% to about 200% by weight of cementitious components. In some embodiments, the water may be included in an amount in the range of about 40% to about 150% by weight of cementitious components. One of ordinary skill in the art, with the benefit of this disclosure, will recognize the appropriate amount of water to include for a chosen application.

[0021] The plugging compositions further comprise lime. The lime is hydrated lime. The hydrated lime is included in the plugging compositions, for example to, form a hydraulic composition with other components of the plugging compositions, such as the pumicite, fly ash, slag, and / or shale. The hydrated lime is included in the plugging compositions in an amount sufficient for a particular application. The hydrated lime is present in an amount in the range of from about 5% to about 10% by weight of cementitious components. For example, the hydrated lime may be present in an amount of about 5%, or about 10%. One of ordinary skill in the art, with the benefit of this disclosure, will recognize the appropriate amount of the lime to include for a chosen application.

[0022] In an embodiment, plugging compositions of the present invention may comprise pumicite and CKD in a weight ratio of from about 1 / 99 to about 99 / 1 with lime present in an amount of from about 5% to about 15% by the combined weight of the pumicite and the CKD. In another embodiment, plugging compositions of the present invention may comprise pumicite and CKD in a weight ratio of from about 65 / 35 to about 80 / 20 with lime present in an amount of from about 5% to about 15% by the combined weight of the pumicite and the CKD. In general, it should be understood that as the amount of the CKD is decreased the amount of the pumicite may be increased, in accordance with embodiments of the present invention.

[0023] It should be understood that use of Portland cement in embodiments of the plugging compositions should be reduced or even eliminated to provide, for example, the desired cost savings and / or reduced carbon footprint. Accordingly, the plugging compositions of the present invention comprise Portland cement in an amount of 0% to about 1%. For example, the Portland cement may be present in an amount of about 1%. In another embodiment, the plugging compositions may be essentially free of Portland cement. As used herein, the term "essentially free" means less than about 1% by weight of cementitious components. In certain embodiments, the plugging composition may contain Portland cement in an amount less than about 0.1 % by weight of cementitious components and, alternatively, less than about 0.01% by weight of cementitious components. By way of example, the plugging composition, in certain embodiments, may be free of Portland cement, in that the plugging composition contains no Portland cement.

[0024] The Portland cements include those classified as Classes A, C, G, and H cements according to American Petroleum Institute, API Specification for Materials and Testing for Well Cements, API Specification 10, Fifth Ed., July 1, 1990. In addition, the Portland cements include those classified as ASTM Type I, II, or III.

[0025] Embodiments of the plugging compositions further may comprise fly ash. A variety of fly ashes may be suitable, including fly ash classified as Class C and Class F fly ash according to American Petroleum Institute, API Specification for Materials and Testing for Well Cements, API Specification 10, Fifth Ed., July 1, 1990. Class C fly ash comprises both silica and lime so that, when mixed with water, it should set to form a hardened mass. Class F fly ash generally does not contain sufficient lime, so an additional source of calcium ions is required for the Class F fly ash to form a hydraulic composition. In some embodiments, lime may be mixed with Class F fly ash in an amount in the range of about 0.1% to about 25% by weight of the fly ash. The lime is hydrated lime. Suitable examples of fly ash include, but are not limited to, POZMIX ®< A cement additive, commercially available from Halliburton Energy Services, Inc., Duncan, Oklahoma.

[0026] Where present, the fly ash generally may be included in the plugging compositions in an amount sufficient to provide the desired compressive strength, density, and / or cost. In some embodiments, the fly ash may be present in the plugging compositions of the present invention in an amount in the range of about 5% to about 75% by weight of cementitious components. In some embodiments, the fly ash may be present in an amount in the range of about 10% to about 60% by weight of cementitious components. One of ordinary skill in the art, with the benefit of this disclosure, will recognize the appropriate amount of the fly ash to include for a chosen application.

[0027] Embodiments of the plugging compositions further may comprise a slag cement. In some embodiments, a slag cement that may be suitable for use may comprise slag. Slag generally does not contain sufficient basic material, so slag cement further may comprise a base to produce a hydraulic composition that may react with water to set to form a hardened mass. Examples of suitable sources of bases include, but are not limited to, sodium hydroxide, sodium bicarbonate, sodium carbonate, lime, and combinations thereof.

[0028] Where present, the slag cement generally may be included in the plugging compositions in an amount sufficient to provide the desired compressive strength, density, and / or cost. In some embodiments, the slag cement may be present in the plugging compositions of the present invention in an amount in the range of about 0.1% to about 99% by weight of cementitious components. In some embodiments, the slag cement may be present in an amount in the range of about 5% to about 75% by weight of cementitious components. One of ordinary skill in the art, with the benefit of this disclosure, will recognize the appropriate amount of the slag cement to include for a chosen application.

[0029] Embodiments of the plugging compositions further may comprise metakaolin. Generally, metakaolin is a white pozzolan that may be prepared by heating kaolin clay, for example, to temperatures in the range of about 600°C to about 800°C. In some embodiments, the metakaolin may be present in the plugging compositions of the present invention in an amount in the range of about 5% to about 95% by weight of cementitious components. In some embodiments, the metakaolin may be present in an amount in the range of about 10% to about 50% by weight of cementitious components. One of ordinary skill in the art, with the benefit of this disclosure, will recognize the appropriate amount of the metakaolin to include for a chosen application.

[0030] Embodiments of the plugging compositions further may comprise shale. Among other things, shale included in the plugging compositions may react with excess lime to form a suitable cementing material, for example, calcium silicate hydrate. A variety of shales may be suitable, including those comprising silicon, aluminum, calcium, and / or magnesium. An example of a suitable shale comprises vitrified shale. Suitable examples of vitrified shale include, but are not limited to, PRESSUR-SEAL FINE LCM material and PRESSUR-SEAL COARSE LCM material, which are commercially available from TXI Energy Services, Inc., Houston, Texas. Generally, the shale may have any particle size distribution as desired for a particular application. In certain embodiments, the shale may have a particle size distribution in the range of about 37 micrometers to about 4,750 micrometers.

[0031] Where present, the shale may be included in the plugging compositions of the present invention in an amount sufficient to provide the desired compressive strength, density, and / or cost. In some embodiments, the shale may be present in the plugging compositions of the present invention in an amount in the range of about 5% to about 75% by weight of cementitious components. In some embodiments, the shale may be present in an amount in the range of about 10% to about 35% by weight of cementitious components. One of ordinary skill in the art, with the benefit of this disclosure, will recognize the appropriate amount of the shale to include for a chosen application.

[0032] Embodiments of the plugging compositions further may comprise zeolite. Zeolites generally are porous alumino-silicate minerals that may be either a natural or synthetic material. Synthetic zeolites are based on the same type of structural cell as natural zeolites, and may comprise aluminosilicate hydrates. As used herein, the term "zeolite" refers to all natural and synthetic forms of zeolite. Examples of suitable zeolites are described in more detail in U.S. Patent No. 7,445,669. An example of a suitable source of zeolite is available from the C2C Zeolite Corporation of Calgary, Canada. In some embodiments, the zeolite may be present in the plugging compositions of the present invention in an amount in the range of about 5% to about 65% by weight of cementitious components. In certain embodiments, the zeolite may be present in an amount in the range of about 10% to about 40% by weight of cementitious components. One of ordinary skill in the art, with the benefit of this disclosure, will recognize the appropriate amount of the zeolite to include for a chosen application.

[0033] The plugging compositions further comprises a set retarding additive. As used herein, the term "set retarding additive" refers to an additive that retards the setting of the plugging compositions of the present invention. Examples of suitable set retarding additives include, but are not limited to, ammonium, alkali metals, alkaline earth metals, metal salts of sulfoalkylated lignins, organic acids (e.g., hydroxycarboxy acids), copolymers that comprise acrylic acid or maleic acid, and combinations thereof. One example of a suitable sulfoalkylated lignin comprises a sulfomethylated lignin. Suitable set retarding additives are disclosed in more detail in United States Patent No. Re. 31,190, the entire disclosure of which is incorporated herein by reference. Suitable set retarding additives are commercially available from Halliburton Energy Services, Inc. under the trademarks HR ®< 4, HR ®< 5, HR ®< 7, HR ®< 12, HR ®< 15, HR ®< 25, HR ®< 601, SCR ™< 100, and SCR ™< 500 retarders. Generally, the set retarding additive is included in the plugging compositions of the present invention in an amount sufficient to provide the desired set retardation. The set retarding additive may be present in the plugging compositions of the present invention an amount in the range of about 0.4% to about 1% by weight of cementitious components. One of ordinary skill in the art, with the benefit of this disclosure, will recognize the appropriate amount of the set retarding additive to include for a chosen application.

[0034] Optionally, other additional additives may be added to the plugging compositions of the present invention as deemed appropriate by one skilled in the art, with the benefit of this disclosure. Examples of such additives include, but are not limited to, strength-retrogression additives, set accelerators, weighting agents, lightweight additives, gas-generating additives, mechanical property enhancing additives, lost-circulation materials, filtration-control additives, dispersants, fluid loss control additives, defoaming agents, foaming agents, oil-swellable particles, water-swellable particles, thixotropic additives, and combinations thereof. Specific examples of these, and other, additives include crystalline silica, amorphous silica, fumed silica, salts, fibers, hydratable clays, microspheres, rice husk ash, elastomers, elastomeric particles, resins, latex, combinations thereof, and the like. A person having ordinary skill in the art, with the benefit of this disclosure, will readily be able to determine the type and amount of additive useful for a particular application and desired result.

[0035] As will be appreciated by those of ordinary skill in the art, embodiments of the plugging compositions of the present invention may be used for forming a seal in a plug-and-abandon operation. An example of a method for plugging and abandoning a well comprises placing a plugging composition in a selected plug location in a well bore and allowing the plugging composition to set to form a plug. The plug location may be selected so that the well bore can be sealed off for abandonment. For example, the plug location may be selected so that selected interval of the well bore may be sealed. In an embodiment, the selected location may be adjacent to a hydrocarbon-containing formation or a water-containing formation. In an embodiment, the plugging and abandoning operation may include the formation of two or more plugs in the well bore. For example, the method may further include placement of a second plugging composition in another selected plug location in the well bore.

[0036] To facilitate a better understanding of the present invention, the following examples of certain aspects of some embodiments are given. In no way should the following examples be read to limit, or define, the scope of the invention.EXAMPLE 1

[0037] A series of sample plugging compositions were prepared at room temperature and subjected to 24-hour crush strength tests at 185°F [85°C] in accordance with API Specification 10 to determine force resistance properties of plugging compositions that comprise CKD, pumicite, and lime. The sample compositions were allowed to cure in a water bath at 185°F [85°C] for twenty-four hours. Immediately after removal from the water bath, crush strengths were determined using a Tinius Olsen tester. The results of the crush strength tests are set forth in the table below.

[0038] Each of the samples had a density of 12.5 ppg [1498 kg / m 3< ] and contained 200-mesh pumicite, Joppa CKD, lime, and water and were free of Portland cement. In the following table, percent by weight is based on the weight of the pumicite and the CKD in the samples. TABLE 1 Crush Strength Tests: Pumicite, CKD, and Lime Sample Water (gal / sk) [litre / 0.028 32m 3< ]Pumicite (% by wt) CKD (% by wt) Lime (% by wt) 24-Hr Crush Strength (psi) [kPa] 19.42 [35.67]6535583.8 [577.8]29.82 [37.17]653510126.3 [870.8]310.15 [38.42]653514229

[1579] 49.33 [35.32]7030575.6 [521.2]59.74 [36.87]703010358

[2468] 610.06 [38.08]703014182.6

[1259] 79.25 [35.02]7525552.8

[364] 89.65 [36.53]752510314

[2165] 99.98 [37.78]752514147

[1014] 109.16 [34.67]8020532.1 [221.3]119.57 [36.23]802010305

[2103] 129.89 [37.44]802014144.8 [998.3]

[0039] Example 1 thus indicates that plugging compositions containing pumicite, CKD, and lime and essentially free of Portland cement may have properties suitable for use in plug-and-abandon operations.EXAMPLE 2

[0040] An additional series of sample plugging compositions were prepared and tested to determine to further analyze the force resistance properties of plugging compositions that comprise CKD, pumicite, and lime. The samples were prepared and allowed to cure in a water bath at 140°F [60°C]. The twenty-four hour and seventh-two hour crush strengths were determined at 140°F [60°C] using a Tinius Olson tester in accordance with API Specification 10. The results of the crush strength tests are set forth in the table below.

[0041] Each of the samples had a density of 15 ppg [1797 kg / m 3< ] and comprised Portland Class H cement, Joppa CKD, 200-mesh pumicite, hydrated lime, a dispersant (CFR ™< -3 cement friction reducer), and / or water, as indicated in the table below. In the following table, percent by weight is based on the weight of the pumicite and the CKD for Samples 13-21 and on the Portland cement for Sample 22. TABLE 2 Crush Strength Tests: Pumicite, CKD, and Lime Sample Portland Cement (% by wt) CKD (% by wt) Pumicite (% by wt) Hydrated Lime (% by wt) Dispersant (% by wt) 24-Hr Crush Strength (psi) [kPa] 72-Hr Crush Strength (psi) [kPa] 13--901050.75306

[2110] 1209

[8336] 14--752551514

[3544] 1988

[13707] 15--7525101520

[3585] 1673

[11535] 16--505051.25876

[6040] 2180

[15031] 17--5050101.251352

[9322] 2280

[15720] 18--257551.5896

[6178] 1402

[9666] 19--2575101.51674

[11542] 1850

[12755] 20--100001200

[1379] 520

[3585] 21--0100102812

[5599] 1261

[8694] 22100--------1202

[8287] 2460

[16961]

[0042] Example 2 thus indicates that plugging compositions containing pumicite, CKD, and lime and essentially free of Portland cement may have properties suitable for use in plug-and-abandon operations.EXAMPLE 3

[0043] An additional series of sample plugging compositions were prepared and tested to determine to further analyze plugging compositions that comprise CKD, pumicite, and lime. The samples were prepared and allowed to cure in a water bath at 140°F [60°C]. The crush strengths were determined at forty-eight hours and 160°F [71.1°C] using a Tinius Olson tester in accordance with API Specification 10. The thickening time for each sample was also determined at 140°F [60°C] in accordance with API Specification 10.

[0044] Each of the samples had a density of 14 ppg [1678 kg / m 3< ] and comprised Portland Class H cement, silica (Silicalite ™< cement additive), Joppa CKD, 200-mesh pumicite, hydrated lime, a dispersant (CFR ™< -3 cement friction reducer), a cement set retarder (HR ®< -5 cement retarder), and / or water, as indicated in the table below. In the following table, percent by weight is based on the weight of the pumicite and the CKD for Samples 23-26 and on the Portland cement for Sample 27. TABLE 3 Crush Strength Tests: Pumicite, CKD, and Lime Sample Portland Cement (% by wt) Silica (% by wt) CKD (% by wt) Pumicite (% by wt) Hydrated Lime (% by wt) Dispersant (% by wt) Set Retarder (% by wt) Thickening Time to 70 bc (hr:min ) 48-Hr Crush Strength (psi) [pKa] 23----75255116:021013

[6984] 24----5050510.75:361701

[11728] 25----5050101.250.755:231717

[11838] 26----2575101.750.44:411523

[10501] 271008--------0.45:472040

[14065] Bc = Bearden units of consistency

[0045] Example 3 thus indicates that plugging compositions containing pumicite, CKD, and lime and essentially free of Portland cement may have properties suitable for use in plug-and-abandon operations.

Claims

1. A well bore plug-and-abandon operation comprising: placing a plugging composition that is essentially free of Portland cement in the well bore, the plugging composition comprising: cement kiln dust in an amount of 25% to 75% by weight of cementitious components; pumicite in an amount of 25% to 75% by weight of cementitious components; hydrated lime in an amount of 5% to 10% by weight of cementitious components; up to 1% of Portland cement by weight of cementitious components; a set retarder in an amount of 0.4% to 1% by weight of cementitious components; water; and a dispersant in an amount of 1 to 1.75% by weight of cementitious components; and allowing the plugging composition to set and form a plug.

2. A well bore plug-and-abandon operation according to claim 1, wherein the water is in an amount of 40% to 200% by weight of cementitious components.

3. A well bore plug-and-abandon operation according to claim 1, wherein the plugging composition comprises: 75% cement kiln dust by weight of cementitious components, 25% pumicite by weight of cementitious components, 5% hydrated lime by weight of cementitious components, and 1% dispersant by weight of cementitious components; or 75% cement kiln dust by weight of cementitious components, 25% pumicite by weight of cementitious components, 10% hydrated lime by weight of cementitious components, and 1% dispersant by weight of cementitious components; or 50% cement kiln dust by weight of cementitious components, 50% pumicite by weight of cementitious components, 5% hydrated lime by weight of cementitious components, and 1.25% dispersant by weight of cementitious components; or 50% cement kiln dust by weight of cementitious components, 50% pumicite by weight of cementitious components, 10% hydrated lime by weight of cementitious components, and 1.25% dispersant by weight of cementitious components; or 25% cement kiln dust by weight of cementitious components, 75% pumicite by weight of cementitious components, 5% hydrated lime by weight of cementitious components, and 1.5% dispersant by weight of cementitious components; or 25% cement kiln dust by weight of cementitious components, 75% pumicite by weight of cementitious components, 10% hydrated lime by weight of cementitious components, and 1.5% dispersant by weight of cementitious components.

4. A well bore plug-and-abandon operation according to any one of the preceding claims, wherein the plugging composition further comprises at least one additive selected from the group consisting of fly ash, slag cement, metakaolin, shale, zeolite, crystalline silica, amorphous silica, fumed silica, salt, fiber, hydratable clay, microsphere, rice husk ash, elastomer, elastomeric particle, resin, latex, and any combination thereof.

5. A well bore plug-and-abandon operation according to any one of the preceding claims, wherein the plugging composition has a density of 8 pounds per gallon [958.6 kilogram / cubic metre] to 16 pounds per gallon [1917 kilogram / cubic metre].

6. A well bore plug-and-abandon operation according to claim 2, wherein the water comprises at least one water selected from the group consisting of freshwater, saltwater, brine, seawater, and any combination thereof.

7. A well bore plug-and-abandon operation according to any one of the preceding claims wherein the plugging composition further comprises at least one additive selected from the group consisting of a strength-retrogression additive, a set accelerator, a weighting agent, a lightweight additive, a gas-generating additive, a mechanical property enhancing additive, a lost-circulation material, a filtration-control additive, a fluid loss control additive, a defoaming agent, a foaming agent, an oil-swellable particle, a water-swellable particle, a thixotropic additive, and any combination thereof.

8. A well bore plug-and-abandon operation according to any one of the preceding claims, further comprising forming a second plug in the subterranean formation using a plugging composition as used in the plug-and-abandon operations in any of the preceding claims.

9. A well bore plug-and-abandon operation according to any one of the preceding claims, wherein the plug is formed at a location to seal a selected interval of the well bore.

10. A well bore plug-and-abandon operation according to claim 9, wherein the location is adjacent to a hydrocarbon-containing formation or a water-containing formation.