RESIN-BASED SEALANT COMPOSITIONS COMPRISING CEMENT KILN DUST AND METHODS OF US BACKGROUND [0001] The invention relates to resin-based sealant compositions and, more particularly, in certain embodiments, to resin-based sealant compositions that comprise cement kiln dust ("C D ) and associated methods of use in servicing well bores. [0002] Sealant compositions may e used in a variety of subterranean applications. For example, in subterranean well construction, a conduit (e.g., pipe string, casing, liners, expandable tubulars, etc.) may be ran into a well bore and cemented in place. The process of cementing the pipe string in place is commonly referred to as "primary cementing." In a typical primary-cementing method, a sealant composition may be pumped into an annulus between the walls of the well bore and the exterior surface of the pipe siring di sposed therein. The sealant composition may set in the annular space, thereby -.forming an annular sheath of hardened, substantially impermeable seal (i.e., a sealant sheath) that may support and position the pipe string in the well bore and may bond the exterior surface of the pipe string to the subterranean formation or the inside of a larger conduit. Among other things, the sealant sheath surrounding the pipe string functions to prevent the migration of fluids in the annulus, as wel a protecting the pipe string f m corrosion. Sealant compositions also may be used i remedial-cementing methods, for example, to seal voids in pipe strings or cement sheaths, to seal highly permeable fo r atio zones or fractures, to place a cement plug, and the like. As used herein the term "void" refers to any type of space, including fractures, holes, cracks, channels, spaces, and the ike. Such voids may include: holes or cracks in the pipe strings; holes, cracks, spaces, or channels in the sheath; and very small spaces (commonly referred to as "miero-annult") between the interior surface of the sealant sheath and the exterior surface of the conduit or between the outer surface of the sealant sheath and the formation or inside surface of a larger conduit. Sealing such voids may prevent t e undesired flow o fluids (e.g., oi gas. water, etc.) and/or fine solids into, or from, the well bore. Sealant compositions a so ma be used in surface applications, for example, construction cementing. [0003] A variety of different sealant compositions, including non-ceraentitious sealants, such as resin-based sealant compositions have bee used in these primary- and secondary-cementing methods. Resin-based sealant compositions may comprise, for example, a liquid hardenabie agent component and a hardening agent component. Because resin-based sealant compositions may have increased flexibility and toughness as compared to conventional cement compositions, the resin-based sealant composition may be used, for example, in applications where increased stresses a d/or increased number of stress cycles may be encountered. For example, resin-based sealant compositions may have applicability in cementing methods performed i shale formations as wells drilled in these types of formations ay require multiple fracturing stages requiring the sealant compositions to have sufficient flexibility an toughness to withstand repeated hydraulic stress and thermal cycles. n addition, resin-based seala compositions may also be placed into the well bore to plug a void in the conduit (e.g., th pipe string) or cement sheath or a void that may have formed between the sheath and a wall o f the well bore or the conduit. While resin-based sealant compositions may be used instead o f conventional eme t ti us-based sealant compositions in certain applications, drawbacks exist with use o f such sealant compositions, including the high cost of the resins, for example. 7 SUMMARY [0004] An embodiment of the present invention provides a method comprising; providing a resin-based sealant composition comprising a liquid hardenable resin component and kiln dust; and allowing the resin-based sealant composition to harden. [0005] Another embodiment of the present invention provides a method of forming a seal in a subterranean formation comprising: introducing a resin-based sealant composition nto a subterranean formation, wherein the resi -base sealant composition comprises a liquid hardenable resin component and cement kiln dust; and allowing the resin-based sealant composition to harden in the subterranean formation. [0006] Another embodiment of the present invention provides a resin-based sealant composition comprising a liquid hardenable resin component: and cement ki n dust. [0007] The features and advantages of the present invention wilt be readily apparent to those skilled n 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 PREFERRED EMBODIMENTS [0008] The present invention relates to resin-based sealant compositions and, more particularly, in certain embodiments, to resin-based sealant compositions that comprise cement Mm dust ("CKD") and associated methods of use in servicing well bores. One of the many potential advantages of the methods and compositions of the present invention is that the C D may be used as a non-hydratmg filler material to lower the consumption of the more expensive components (e.g., hardenable resin component, etc.) tha are typically used in resin-based sealant compositions. Yet another potential advantage s that the CKD may aid the sealing of voids such as cracks that ay form in the hardened sealant composition. B way of example, the CK may hydrate an harden upon contact with water, for example, to counteract the potential formation of voids (e.g., cracks, micro-annuii, etc.) that ay form in die hardened sealant composit ion [0009] Embodiments of the present invention disclose resin-based sealant compositions comprising a liquid hardenable .resin component and CKD. In some embodiments, the resin-based sealant composition may further comprise a liquid hardening agent component for facilitating the set of the hardenable resin component, in other embodiments, the liquid hardenable resin component may auto-catalyze and not require the hardenable resin co ponen for setting. The resin-based sealan compositions may be used in a number different subterranean applications in which the sealant composition may be introduced into a subterranean formation and allowed to harden. One example of a subterranean application includes primary-cementing methods in which th resin-based sealant composition may be allowed to harden in a wel l-bore ann us Another example of a subterranean application includes remedial-cementing methods in which the resin-based sealant composition may b allowed, for example, to harden and sea! voids m pipe strings or cement sheaths, to seal highly permeable formation zones or fractures, to plac a cement plug, and the like. [0010] In some embodiments, the liquid hardenable resin component of the resinbased sealant composition may comprise a hardenable resin, an optional solvent, and an optional aqueous diluent or carrier fluid. As used herein, the term "resi ' refers to any of a number of physically similar polymerized synthetics or chemically modified natural resins including thermoplastic materials and thermosetting materials. Examples of hardenable resins that may be use in the liquid hardenable resin component include, but are not limited to, epoxy-based resins, novolak resins, polyepoxide resins, phenol -aldehyde resins, ureaaldehyde resins, uretharte resins, phenolic resins, ruran resins ftiran/furfuryl alcohol resins, phenolic/latex resins, phenol formaldehyde resins, hisphenol A digSycidyl ether resins, butoxymethyl butyl glyckly! ether resins, bisphenol A-epichlorahydrin resins, bisphenol resins, glyeidyl ether resins, polyester resins and hybrids copolymers thereof, polyurethane resins and hybrids and copolymers thereof, aerySate resins, a d mixtures thereof. Some suitable resins, such as epoxy resins, may be cured with an internal catalyst or activator so that when pumped downhole. they ma be cured using only time and temperature. Other suitable resins, such as furan resins generally require a time-delayed catalyst or an external catalyst to he p activate the polymerization of the resins if the cure temperature is low (i.e., less than 250 F but will cure under th effect of time and temperature if the formation temperature is above about 250°F, preferably above about 3 F t is withi the ability of one skilled in the art, with the benefit of thi disclosure, to select a suitable resin for us in embodiments of the present invention an to determine whether a catalyst is required to trigger curing. One resin that may be used in particular embodiments of the present invention is the consolidation age commercially avaiiable from Halliburton Energy Services, Inc., of Duncan, Ok!a., under the trade name "EXPEDITE™-." [00 ] Selection of a suitable resin ay be affected by the temperature of the subterranean formation to which the composition w ll be introduced. By way of example, for subterranean formations having a bottom hole static temperature ( B ST ) ranging from about 6 F to about 25 F, two-component epoxy-h sed resins comprising a bardenabie .resin component and a hardening agent component containing specific hardening agents may be preferred. For subterranean formations having a BUST ranging from about 300°F to about 600° F, a furan-based resin may be preferred. For subterranean fo rmations having a SHST ranging from about 2 0 F to about 40 F, either phenolic-based resin or a onecomponent HT epoxy-based resin may be suitable. For subterranean formations having a B ST of at least about 5' F, a phenol/phenol br a dehyde furfuryl alcohol resin may also be suitable. [0012] Generally, th bardenabie resin may be included in the liquid hardenabie resin component in an amount in a range of from about 5% to about 1 0% by volume of the liquid bardenabie resin component. n particular embodiments, the hardenabie resin may be included in th liquid hardenabie resin component in an amount in a range of from about 75% to about 100% by volume of the liquid hardenabie resin component. It is withi the ability of one skil led in the art with the benefit of this disclosure to determine how much of the hardenabie resin may be needed to achieve the desired results. Factors that may affect this decision include the type of hardenabie resin and liquid hardening agent used in a pa ieuiar appl ica ion 0 ί 3] In some embodiments, solvent be added to the res n to reduce ts viscosity for ease of handling, mixing and transferring. However, in particular embodiments, it may be desirable not o use such a solvent for environmental or safety reasons t is within the ability of one skilled in the art with the benefit of this disclosure to determine f and how much solvent may be needed to achieve a viscosity suitable to the subterranean conditions of a particular application. Factors that may affect this decision include geographic location of the well the surrounding weather conditions, and the desired long-term stability of th resin-based sealant composition. [0014] Generally, amy solvent that is compatible th the hardenable resi and that achieves the desired viscosity effect may be suitable for use in the liquid hardenable resin component of the resin-based sealant composition. Suitable solvents may include, but are not limited to, -polyethylene glycol, butyl lactate, dipropyfene glycol methyl ether, dipropy!ene glycol dimethyl ether, dimethyl for an ide, diethyienegiycol methyl ether, ethyleneglyco! butyl ether, diethyienegiycol butyl ether, propylene carbonate, dMimonene, fatty acid methyl esters, and combinations thereof. Selection of an appropriate solvent may he dependent on the hardenable resin chosen. With the benefit of this disclosure, the selection of an appropriate solvent should be within the ability of o e skilled in the art. i some embodiments, the amount of the solvent use in the liquid hardenable resin component may be in the range of about 0. % to about 30% b weight of the liquid hardenable resin component. Optionally, the liquid hardenable resin component may e heated to reduce its viscosity, in place of, or in addition to, using a solvent. [00 ] Generally, the liquid hardenable resin component may be included in embodiments of the resin-based sealant composition in an amount in a range from about 5% to about 90% by volume of the resin-based sealant composition. In particular embodiments, the liquid hardenable resin component may be included in the resin-based. sealant composition i a amount in a range of from about 50% to about 75% by volume of th resin-based sealant composition, [00 ] in some embodiments, the resin-based sealant composition ma further comprise a liquid hardening agent component comprising a hardening agent a d an optional silane coupling agent. As used herein, "hardening agent" refers t any substance capable o transforming the hardenable resi into a hardened, consolidated mass. Examples o suitable hardening agents include, but are not limited to, aliphatic amines, aliphatic tertiary amines, aromatic amines, cye!oaliphatie amines, heterocyclic amines, a ido amines, polyamides, po!yethy! amines, polyether amines, polyoxyalkylene amines, carboxyllc anhydrides, triethy!eoetetraamine, ethylene diamine, N-cocoalkyltrimethyJene, i ophoron diamine, Naminophenyl pipera ne imidazoline, 2