WE LL TREAT TMENT COM POSITIONS AND MIETIODS UTILIZING NANO-PARTICLES BACKGROUND [0001] The present invention relates to well treatment compositions and methods 5 utilizing ano-particles and, more particularly, in one or more embodiments, to well cement compositions and/or well completion fluids that comprise nano-particles. [0002] In general, well treatments include a video variety of methods that may be perfoned in oil, gas, geothermal and/or water wells, such as drilling, completion and workover Methods. T drilling, completion and workover methods may include, but are not 10 limited to, drilling, fracturing, acidizing, logging, cementing, gravel packing, perforating and conforniance methods, Manv of these well treatments are designed to enhance and/or facilitate the rccovry of desirable fuids from a subterranean well [0003] In cementing methods, such as well construction and remedial ecmenting, well cement compositions are commonly utilized. or example, it subterranean well 15 construction, a pipe string (e.g.. casing and liners) may be run into a well bore and cemented in place using a cement composition. I'he process of cementing the pipe string in place is commonly referred to as "primary cementing In a typical primary ceni. ting method, a cement composition may be pumped into an annulus between the walls of the well bore and the exterior surface oif the pipe string disposed therein, The cement composition sets in the 2 0 annular space, thereby forming a t annular sheath of hardened, substantially impenneable cement that supports and positions the pipe string in the well bore and bonds the exterior surface of the pipe string to the subterranean formation, Among other things, the annular sheath of set cement surrounding the pipe string functions to prevent the migration of fluids in the annulus, as well as protecting the pipe string from corrosion. Cement compositions 25 also may be used in remedial cementing methods, such as squeeze cementing and the placement of cement plugs. [0004] In operation, the annular sheath of cement formed between the well bore and the pipe string often suffers structural failure due to pipe movements which cause shear stresses to be exerted on the set cement, Such stress conditions are commonly the result of 30 relatively high fluid pressures and/or temperatures inside the cerented pipe string during testing perforating, fluid injection or fluid production. For example, such stress nmay occur in wells subjected to stean recovery or production of hot formation fluids from high temperature formations, The high-internal pipe pressure and/or temperature can result in the expansion of the pipe string, both radially and lo.nituidinally, which places stresses on the 35 cement sheath causing the cement bond between the exterior surfaces of the pipe or the well
I
bore walls, or both, to fail and thus allow leakage of formation fluids and so forth, Accordingly, it may be desirable for the cement composition utilized for cementing pipe strings in the well bores to develop high strength after setting and to have sufficient resiliency (e.g, elasticity and ductili ty) to resist loss of the cement bond between the exterior 5 surfaces of the pipe or the well bore walls, or both, Also, it may be desirable for the cement composition to be able to resist cracking and/or shattering that may result from other forces on the cement sheath. For example, it may be desirable for the cement sheath to include structural characteristics that protect its structural integrity from forces associated with formation shifting, overburden pressure. subsidence, tectonic creep pipe movements, 10 impacts and shocks subsequently generated by drilling and. other well operations. [0005] In addition to including components that improve mechanical properties of the cement, in a number of cementing methods, it may also be desirable to include one or more set accelerators in the well cement compositions to counteract certain constituents and/or environmental characteristics that excessively slow set times. For example, among 15 other things. low temperatures and cement additives (e,g,. fluid loss control additives and dispersants) can cause or contribute to an excessive set time for a cement composition. Accordingly, in certain situations, it may be desirable to reduce the set time by including a set accelerator in the cement composition, That is, the set accelerator may be included in a cement composition to counteract components of the cement composition or conditions 20 surrounding the cement composition that are causing an excessive set time. [0006] Completion fluids are another type of fluid that may be used in well treatments, A completion fluid is typically a solids-free liquid that is used, in part, to control well pressure while completing the well. The completion fluid is typically placed into the well bore after drilling, but before the start of production, to facilitate completion of the well, 25 which typically involves preparing the bottom of the well bore to the required specifications, running in the production tubing and its associated downhole equipment, and optionally carrying out production enhancement operations., if desired. The completion fluid should generally be chemically compatible with the reservoir formation and fluid and should not damage the permeability of the formation or other equipment placed into the well bore, such 30 as production screens. To avoid such damage, the completion fluid is typically filtered to a high degree to remove any solids that could be introduced into the near-well bore region or downhole equipment. [0007] Brines, such as chlorides, bromides, and formats, have typically been used as completion fluids. However, these metal brines can be expensive, corrosive, and difficult 35 to handle. For example; brines may tend to corrode and damage the downhole equipment in 2 many instances .especially those of a delicate nature such as production screens. Brines may also cause undesired precipitation reactions that can damage the permeability of the producing formation. Purthennore, disposal of the brines may be difficult and costly especially on land where environmental regulations prohibit the placement of high 5 concentrations of chlorides and other ions into landfills, SUMMARY [0008] 'The present invention relates to well treatment compositions and methods utilizing nano-particles and, more particulady, in one or more embodiments, to well cement compositions and/or well completion fluid's that comprise nano-particles. 5 [0009] An embodiment of the present invention provides a method of completing a well comprising: including nano-particles in a completion fluid; and using the completion fluid in completing the well, [0010] Another embodiment of the present invention provides a method of completing a well comprising: providing a completion fluid comprising nano-particles; and 10 introducing the completion fluid into a well bore, [00111 Another embodiment of the present invention provides a method of completing a well comprising: including nano-particles having a particle size of from about I nanometer to about 100 nanometers in a completion fluid, wherein the nano-particlus comprise at least one nano-particle selected froni the group consisting of nano-alumina, 15 nano-zine oxide, nano-boron, nano-iron oxide, nano-silica, and any combination thereof; and using the completion fluid in completing the well. [0012] The features and advantages of the present invention will be apparent to those skilled in the art upon reading the following description of specific embodiments. 4 - 4a In an embodiment of the invention there is provided a method of completing a well comprising: including nano-particles in a completion fluid, wherein the nano particles are selected from the group consisting of nano-silica, nano-alumina, nano zinc oxide, nano-boron, nano-iron oxide, nano-barium sulphate, nano-manganese tetraoxide, nano-magnesium oxide, nano-calcium carbonate, nano-graphite, nano barium oxide, nano-cerium oxide, nano-lanthium oxide, nano-titanium dioxide, nano-clay, nano-aluminosilicate, and any combination thereof, wherein micron-sized or larger particles are not present in the completion fluid; and using the completion fluid in completing the well. In an embodiment of the invention there is provided a method of completing a well comprising: providing a completion fluid comprising nano-particles, wherein the nano-particles are selected from the group consisting of nano-silica, nano alumina, nano-zine oxide, nano-boron, nano-iron oxide, nano-barium sulphate, nano manganese tetraoxide, nano-magnesium oxide, nano-calcium carbonate, nano graphite, nano-barium oxide, nano-cerium oxide, nano-lanthium oxide, nano titanium dioxide, nano-clay, nano-aluminosilicate, and any combination thereof, wherein micron-sized or larger particles are not present in the completion fluid, and wherein the completion fluid does not plug production screens; and introducing the completion fluid into a well bore. In an embodiment of the invention there is provided a method of completing a well comprising: including nano-particles having a particle size of from 1 nanometer to 100 nanometers in a completion fluid, wherein the nano-particles comprise at least one nano-particle selected from the group consisting of nano alumina, nano-zine oxide, nano-boron, nano-iron oxide, nano-silica, nano-barium sulphate, nano-manganese tetraoxide, nano-magnesium oxide, nano-calcium carbonate, nano-graphite, nano-barium oxide, nano-cerium oxide, nano-lanthium oxide, nano-titanium dioxide, nano-clay, nano-aluminosilicate, and any combination thereof, wherein micron-sized or larger particles are not present in the completion fluid, and wherein the completion fluid does not plug production screens; and using the completion fluid in completing the well.
DESCRIPTION OF SPECIFIC EMBODIMENTS [0013] The present invention relates to well treatment compositions and methods utilizing nano-particles and, more particularly, in one or more embodiments, to well cement comnpositions andior well completion fluids that Comprise nano-particles. 5 Cement Composition Embodiments [0014] An exemplary embodiment of the cement compositions of the present invention comprises cement, water and particulate nano-silica. Those of ordinary skill in the art will appreciate that the exeniplary cement compositions generally should have a density suitable for a particular applicaton. By Way of example. the cement composition may have 10 a density in the range of from about 4 pounds per gallon ("'b/gal") to about 20 lb/gal. in exemplary embodiments. the cement compositions may have a density in the range of from about 8 lb/gal to about 17 lb/gal. Exemplary em bodirments of the cement compositions iay be foamed. or unfoamed or may comprise other means to redchee their densities such as hollow microspheres, low-density elastic beads, or other density-reducing additives known 15 in the art. Those of ordinary skill in the art. with. the benefit of this disclosure, will recognize the appropriate density for a particular application. [0015] Exemplary embodiments of the cement compositions of the present invention comprise a cement Any of a variety of cements suitable for use in subterranean cementing operations may be used in accordance with exemplary embodiments of the present invention. 20 Suitable examples include hydraulic cements that comprise calcium, aluminum, silicon, oxygen and/or sulfur, which set and harden by reaction with water, Such hydraulic cements, include, but are not limited to, Portland cements, pozzolana cements, gypsuin cements, high alumina content cements, slag cements, silica cements and combinations thereof, In certain embodiments, the hydraulic cement may comprise a Portland cement. The Portland cements 25 that may be suited for use in exemplary embodiments of the present invention are classified as Class A, C, H and. G Cements according to American Petroleum Institute, API Specificafion finr Material and Testing 1 Ceents, API Specification 10, Fifth Ed, July 1, 1990, [0016] The water used in exemplary embodiments of the cement compositions of the 30 present invention may be freshwater or saltwater (e.g. water containing one or more salts dissolved therein. seawater, brines, saturated saltwater, etc.). In general, the water may be present in an amount sufficient to form a pumpable slurry. In exemplary eibodiments, the water may be present in the cement compositions in an amount in the range of from about 33% to about 200% by weight of the cement on a dry basis ("bwoc"), In exemplary 5 embodiments, the water may be present in an amount in the range of from about 35% to about 70% bwoc. [0017] In addition, exemplary embodiments of the cement compositions comprise nanosilica. The nano-silica may be described as particulate nano-silica. That is, the nano 5 silica may be particulate in nature and not, for example, a colloidal silica or a suspension of silica in solution. Indeed, in one embodiment, the particulate nano-silica may be added to the cement composition as a dry nano-silica powder, Generally, the particulate nano-silica may be defined as nano-silica having a particle size of less than or equal to about 100 nm. [or example, the particulate nano-silica may have a particle size in the range of from about I 10 nm to about 100 nm (about I xJ 01 m to about 100x i 0 m) In certain exemplary embodiments, the particulate nano-silica may have a particle size of less than or equal to about 50 nm., For example, the particulate nano-silica may have a particle size in the range of from about 5 un to about 50 nm. In further exenplary embodiments, the particulate nano-silica may have a particle size of less than or equal to about 30 nm. For example, the 15 particulate nano-silica may have a particle size in the range of from about 5 nm to about 30 nm, However, it should be noted that the particulate nano-silica may be utilized in combination with differently sized silica particles in accordance with present embodiments. For example, a number of silica particles with particle sizes greater than 100 nm may be included in a cement composition in accordance xvith present embodiments, 20 [0018] It is now recognized that the particulate nano-silica utilized with present embodiments, which may include silicon dioxide, may have an impact on certain physical characteristics of resulting cements. For example, relative to inclusion of colloidal silica or larger silica particles in a cement slurry, inclusion of particulate nano-silica in the cement slurry may provide improved mechanical properties, such as compressive strength, tensile 25 strength, Young's modulus and Poisson's ratio, In addition, the particulate nano-silica also may be included in the cement composition as a set accelerator to accelerate the set time of the resultant cement composition, Accordingly, a cement composition in accordance with present embodiments may comprise a sufficient amount of particulate nano-silica to provide the desired characteristics in a resulting cement. In exemplary embodiments, the particulate 30 nano-silica may be present in the cement composition in an amount in the range of front about 1% to about 25% bwoc, In exemplary embodiments, the particulate nano-silica may be present in the cement composition in an amount in the range of from about 5% to about 15% bwoc, [0019] Other additives suitable for use in subterranean cementing operations also 35 may be added to exemplary embodiments of the cement compositions. Examples of such 6 additives include, strength retrogression additives, set accelerators. weighting agents, weight-reducing additives. heavyweight additives, lost-circulation materials; filtration control additives, dispersants. defming agents, foaming agents, and combinations thereof Specific examples of these, and other, additives include crystalline silica, amorphous silica, 5 salts. fibers, hydratable clays, vitrified shale, rmicrospheres, fly ash, lime, latex, thixotropic additives, 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 use fiti for a particular application and desired result. [0020] As will be appreciated by those of ordinary skill in the art, exemplary 10 embodiments of the cement compositions of the present invention may be used in a variety of subterranean applications, including primary and remedial cementing. Exemplary embodiments of the cement compositions may be introduced into a subterranean formation and allowed to set therein. Exemplary embodiments of the cement compositions may comprise cement, water and the particulate nano-silica, By way of example, in exemplary 15 primary CemtI..ing embodiinents, a cement composition may be introduced into a space between a subterranean formation and a pipe string located in the subterranean formation. The cement composition may be allowed to set to form a hardened mass in the space between the subterranean formation and the pipe string, In addition, in exemplary remedial cementing embodiments, a cement composition may be used, for example, in squeeze 20 cementing operations or in the placement of cement plugs, One or more hydrocarbons (e.g., oil, gas, etc.) may be produced from a well bore penetrating the subterranean formation. [0021] While the preceding discussion is directed to the use of particulate nano silica, those of ordinary skill in the art will also appreciate that it may be desirable to utilize other types of nano-particles, in accordance with embodiments of the present invention. 25 Elxamples of such nano-particles include nano-alunina, nano-zinc oxide, nano-boron, nano iron oxide and combinations thereof, In certain exemplary embodiments, the nano-particles may be particulate in nature and not, for example, a colloidal nano-particle or a suspension of the nano-particle in solution. Furthermore, while the preceding discussion is directed to the use of particulate nano-silica in well cementing methods, those ofordinary skill in the art 30 will appreciate that the present technique also encompasses the use of nano-particles in any of a variety of different subterranean treatments. For example, the nano-particles may be included in any of a number of well treatment fluids that may be used in subterranean treatments, including drilling fluids, completion fluids, stimulation fluids and well clean-up fluids, In accordance with another embodiment. the nano-particles may be included as 35 proppant in a well treatment fluid, For example, a well treatment fluid containing the nanoparticles may be introduced into a subterranean formation at or above a pressure sufficient to create or enhance or more fractures in the subterranean formation. Enhancing a fracture includes enlarging a pre-existing fracture in the formation., At least a portion of the nano particles may be deposited in the one or more fractures such that the fractures are prevented 5 from fully closing upon the release of pressure, forming conductive channels through which fluids may flow to (or from) the well bore. [0022] In addition to the use of the nano-particles without encapslation, embodiments of the present invention may include encapsulation of the nano-particles to facilitate transportation and incorporation of the nano-particles in well treatment fluids (eg 10 cement compositions). Specifically, encapsulation of the nano-particles in accordance with present embodiments may include enclosing the nano-particles within an outer coating or container in particulate forn, Exemplary methods of encapsulation are set forth in U.S. Patent Nos. 5,373,901; 6,444.316; 6,527,051; 6;554,071: 7,156,174; and 7,204,312, the relevant disclosures of which are incorporated herein by reference. 15 [0023] Various types of encapsulation may be employed such that the nano-particles (e.g. the particulate nrano-silica) are contained but retains its particulate nature and, thus, retains its corresponding impact on physical properties of cement sluerris. For example, the nano-particles may be encapsulated within a bag, capsule, layer, coating or the like. Further, the material utilized to encapsulate the nano-particles may be selected to acilitate 20 transportation and/or incorporation of the nano-particles into a well treatment fluid. For example, to facilitate handling of the nano-partieles and/or to facilitate timed release of the nano-particles the encapsuation material may be degradable. This may facilitate handling of the nano-particles by allowing inclusion of the encapsulated nano-particles in a well treatment fluid without requiring that the nano-particles first be removed from the 25 encapsulating material. Ftirther, the encapstlating material may be designed to degrade at a certain rate when in contact with certain materials (esg, water) so that the nano-particles are released into the well treatment fluid at a desired time. Exemplary water-dissolvable materials that may be utilized to encapsulate ihe nano-particles are described in US Patent Nos. 4,961,790 and 5,783,541, the relevant disclosures of which are incorporated herein by 30 reference. [0024] In accordance with exemplary embodiments, the cement compositions of the present invention may utilize a packing volume fraction suitable for a particular application as desired. As used herein, the term "packing volume fraction" refers to the volume of the particulate materials in a fluid divided by the total volume of the fluid, The size ranges of 35 the preferred particulate materials are selected, as well as their respective proportions, in 8 order to provide a maximized packing volume fraction so that the fluid is in a hindered settling state, It is known that, in such a state, the particulate materials behave "collectively" like a porous solid material. The hindered settling state is believed to correspond, in practice, to a much higher solid material concentration in the fluid than that present in the 5 some traditional cement compositions, [0025] The present embodiments may include a combination of at least three features to obtain a maximum packing volume fraction. One is the use of at least three particulate materials wherein the at least three particulate materials are in size ranges "disjointed" from one another. In some embodiments, each of the three particulate materials 10 may include a dilerent particle size selected from the following ranges: about 7 nm to about 50 nm, about 0.05 microns to about 0.5 microns, 0.5 microns to about 10 microns; about 1) microns to about 20 microns, about 20 microns to about 200 microns, about 200 microns to about 800 microns, and greater than about I millimeter. For example, a first particulate material may include particles sized. from about 7 nm to about 50 nm, a second particulate 15 material may include particles sized from about 0.05 microns to about 0.5 microns, arid a third particulate material may include particles sized from about 10 microns to about 20 microns. In accordance with present embodiments, the first particulate material includes at least one of nano-silica, nano-alumina, nano-zinc oxide, nano-boron, nan o-iron oxide or combinations thereof, Another feature of present embodiments may include a choice of the 20 proportions of the three particulate materials in relation to the mixing, such that the fluid, when mixed, is in a hindered settling state. Another feature may include the choice of the proportions of the three particulate materials between each other, and according to their respective size ranges, such that the maximum packing volume fraction is at least substantially achieved for the sum total of all particulate materials in the fluid system, 2.5 Packing volume fraction is described in further detail in United States Patent Nos. 5,518,996 and 7,213,646, the relevant portions of which are incorporated herein by reference, Completion Fluid Embodiments [0026] As previously mentioned, the nano-particles may be included in completion fluids in accordance with embodiments of the present invention. The nano-particles may be 30 included in the completion fluids to provide a number of different benefits, For example, the nano-particles may be used to enhance or otherwise improve the rheological properties of the completions fluids,. By way of further example, the nano-particles may be included in the completion fluids as weighting materials to increase the density of the fluid, Because the nano-particles are nano-sized, it is believed that they should not undesirably plug formation 35 permeability or other downhole equipment, such as production screens, and thus can be 9 included in completion fluids. In addition, the inclusion of the nano-particles in completion fluids may have further beneficial effects, especially in shale formations. For example, it is believed that the nano-particles may prevent the influx of well bore fluids into the nano porosity often found within shale formations, such as oil whales, by sealing these pores., 5 which isolates and stabilizes the shale formation from the destabilizing hydraulic forces from the well bore. [0027] An exemplary embodiment of the completion fluids may comprise nano particles. In some embodiments, the nano-particles may have a particle size range in a range of less than or equal to about 10 [0028] Generally, the "nano-particles" may be defined as having a mean particle size of less than I micron. For example, nano-particles may have a mean particles size in a range of from about I nm to less than 1 micron. In some embodiments, the nano-particles may have a mean particles size in a range of from about I nm to about 800 urn and, alternatively, from about I nm to about 100 nm. In one particular embodiment, the nano-particles may 15 have a mean particle size in a range of about 20 nm to about 100 nm. in specific embodiments, the nano-particles may have a particle size of about I n, about 10 tim, about 50 nm, about 100 iin, about 200 nu, about 400 nm, about 600 nm, or about 800 nm, In some embodiments, the nano-particles may be provided in colloidal iorm, for example, a colloidal nano-particle or a suspension of the nano-particle in a fluid, In some embodiments, 20 the nano-particle may be a particulate nano-particle. The nano-particles may be encapsulated or otherwise contained as discussed above. Examples of suitable nano-particles include nano-alumina, nano-zine oxide, nano-boron, nano-iron oxide, and nano-silica. Additional examples of suitable nano-particles include other nano-sized materials, including nano-barium sulphate, nano-manganese tetraoxide, nano-magnesium oxide, nano-calcium 25 carbonate, nano-graphite, nano-barium oxide. nano-cerium oxide,. nano-Ianthiumn oxide, nano-titanium dioxide, nano-clay, and nano-ahuninosilicates, Combinations of different nano-particles may also be used. In some embodiments, the nano-particle is not acid soluble. [0029] The nano-particles may be included in a completion fluid in an amotint 30 sufficient for a desired application. For example, the nano-particles may be included in a completion fluid in an amount sufficient to weight the fluid to a desired density. In some embodiments, the nano-particles may be present in the completion fluid in an amount in a range of [rom about 0 1% to about 70% by volume of the completion fluid. In specific embodiments, the nano-particles may be present in an amount ranging between any of and/or 35 including any of about 0.1%, about 1%, about 10%., about 20%, about 30%, about 40%. 10 about 50% about 60%, or about 70% by volume of the completion flrid, One of ordinary skill in the art, with the benefit of this disclosure, should be able to select an appropriate amount of the nano-particles to use for a particular application, [00301 In some embodiments, the completion fluids may comprise a base fluid, such 5 as an oil-based fluid or a water-based fluic. Oil-based fluids may comprise olefins. internal oletins, alkanes, aromatic solvents, cycloalkanes, liquefied petroleum gas, kerosene, diesel oils, crude oils, heavy oils, gas oils, fuel oils, paraffin oils, mineral oils, low toxicity mineral oils, esters, amides, synthetic oils (e.g- polyolefins), polydiorganosiloxanes, siloxanes, organosiloxanes, ethers, acetals, dialkylcarbonates hydrocarbons; and combinations thereof 10 Water-based fluids may comprise fresh water or salt water, such as a brine or seawater. The base fluid may be present in an amount in a range of from about 25% to about 99% by volume of the completion. fluid, [0031] Other additives suitable for use in completion operations may also be included in the completion fluids in embodiments of the present invention. Examples of 15 such additives includes salts, surfactants, fluid-loss-control additives, gases such as nitrogen or carbon dioxide, surfice-modifying agents, foamers, corrosion inhibitors, scale inhibitors, clay-control agents, biocides, friction reduces, antifoam agents, dispersants, fIloceulants. 11S scavengscavengers, oxygen avengers, lubricants. viscosifiers, breakers, wetting agents, and combinations thereof. A person having ordinary skill in the art, with the benefit 20 of this disclosure, should readily be able to determine the type and amount of additive useful for a particular application, [0032] The completion fluids may. have a density as desired for a particular application, In general, the completion fluid should have a density sufficient to, for example, control formation pressures. As previously described, the nano-particles may be used in 25 some embodiments as weighting agents to increase the density of the completion fluid. For example, the nano-particles may be included in the completion fluid in an amount sufficient to weight the completion fluid, In some embodiments. the completion fluid may have a density in the range of from about 7.5 lb/gal to about 22 lb/gal, and alternatively front about 12 lb/gal to about 18 lb/gal One of ordinary skill in the art, with the benefit of this 30 disclosure, should be able to determine an appropriate density of the completion fluid for a particular application. [0033] As will be appreciated by those of ordinary skill in the art, with the benefit of this disclosure, embodiments of the completions fluids of the present in vention may be used in a variety of completion operations, For example, the completion fluids may be used in 35 operations afler drilling, but before the start of production. In some embodiments, the 11 completion operation may include preparing the bottom of the well bore to the required specifications. running in production tubing and its associated downhole equipment, or carrying out production enhancement operations. By way of example, the completion fluid may he present in the well bore while equipment, such as screens, production liners, and/or 5 downhole valves, is run into the well bore, In one embodiment, the completion fluid may be present in the well bore while perforations are formed in the casing disposed in the well bore. Among other functions, the completion fluid should act to control formation pressures. [0034] An embodiment of the present invention may comprise a method of completing a well that comprises providing a completion fluid comprising nano-particles and 10 introducing the completion fluid into a well bore, in some embodiments, downhole equipment may be run into the well while the completion fluid is in the well bore. The downhole equipment may include, for exam ple, screens, production liners, and/or downhole valves. One particular example of a type of downhole equipment that is susceptible to phigging by solids-aden fluids, such as drilling fluids, is wire-wrapped screens. Wire 15 wrapped screens may be used, for example, where a well bore liner having a porous screen may be required to mechanically hold back the formation sand. Because the nano-particles are nano-sized, the nano-particles should not undesirably plug the downhole equipment in contrast, if nicron-sized or larger particles are included in the completion fluids, the downhole equipment, as well as the formation permeability, would be susceptible to 20 plugging events. [0035] To facilitate a better understanding of the present technique, the following examples of some specific embodiments are given. In no way should the following examples be read to limit, or to define, the scope of the invention, EXAMPLE I 25 [0036] Five different cement slurries (i e.. Slurry A, Slurry B, Slurry C, Slurry D and Slurry E) were prepared. The slurries and resulting set cements were then tested to determine setting or thickening times and other physical properties of each of the live different slurries. As set forth below, the respective test results for the five different scurries demonstrate that inclusion of particulate nano-silica in the slurry reduces the set time and 30 increases the strength of the resuming cement relative to cements resulting from inclusion of the other silica components that were tested. [0037] Slurries A, B, C and 1) were prepared by dry blending dry components with cement prior to adding water to form the respective slurry. Slurry E was prepared by dry blending dry components with cement prior to adding water and then adding colloidal silica 12 to forni the respective slurry. Further, each of the five slurries included a different type of silica, Two of the five slurries included particulate nano-silica in accordance with present embodiments, and the other three included silica in different forms and sizes (cig. colloidal silica and micro-silica). While the silica included in each of the five slurries was different., 5 the other components utilized in each of the five flurries were similar. Specifically, in addition to a specific type of silica, each of the five slurries included 100% bwoc of Class G cement, 0.5% bwoc of a retarder, and sufficient water to make the density of the slurry approximately 12.00 lbsgal The specific retarder utilized in the slurries was HR-5 cement retarder, which is a sulfomethylated lignosulfonate. It should be noted that 1HR5 cement 10 retarded is available from Halliburton Energy Services, Inc. and is described in U$.S Patent No. RE31 190. [0038] A.s set forth above, each of the five slurries included a different type of silica and sufficient water to make the resulting slurry have a density of 12,00 lb/al. Slurries A and B included particulate nano-silica in accordance with present embodiments and 15.36 15 ial/sk of water. Specifically, Shlr-ry A included 15% bwoc of particulate nano-silica having a particle size of approximately 30 nin, and Slurry B included particulate nano-silica having a particle size of approximately 10 tim, Slurry C included 15% bwoc of S lICALITE cement additive and 15,68 gal/sk of water. SILICALITE (compacted) cement additive, which is available from Halliburton Energy Services, Inc., iuncan, Oklahoma, is an 20 amorphous silica generally sized in a range trom about 2.5 microns to about 50 microns. Slurry D included 1I5% bwoc of MIICROSAND cement additive and 15.77 gal/sk of water. MICROSAND cement additive, which is available from Haliburton E3nergy Services, Inc., Duncan, Oklahoma, is a crystalline silica ground to a substantially uniformi particle size distribution of approximately 5 to 10 microns, Slurry F included 5,12 gal/sk of GasCon 2.5 469"" lightweight cement additive and 10.09 gal/sk of water. iASCOND 469 lightweight cement additive is available from iIall iburton Energy Services, hic, Duncan, Oklahoma, and may be defined as a colloidal silicic acid suspension containing suspended silcic acid particles generally having a particle size of less than about 20 rim. [0039] After the five slurries were prepared., tests were performed to determine 30 various physical character stics associated with inclusion of the different silica components in each of the associated cement compositions, One of these tests was performed to measure a thickening time associated with each of the five slurries. Specifically, the total thickening time 0TTT) associated with each cement slurry was determined by performing a thickening time test in accordance with API Recommended Practice 10, AP1Speci/cadonfor Materials 35 and TeSn'g tfir Well Cements. The measurement of the TTT for each sltrry was based on 13 the respective slurry reaching a consistency of 70 Bearden units (Bc) at 80 *. The results of these measurements are set forth for each of the five slurries in Table I below. [0040] Additional tests were performed on the cement slurries to determine force resistance properties (e.g, compressive strength, shear-bond strength, and tensile strength) 5 for each of the slurries. Each of the force-resistance property tests was performed on the respective cement slurries at a temperature of 801F and after the scurries had set for 72 hours. The force-resistance property tests included nondestructive and destructive ultrasonic strength tests, a compressive-strength test, a shear-bond test, and a tensile-strength test. The nondestructive and destructive ulrasonic analyzer tests were conducted using a UICA 10 ultrasonic cement analyzer to determine a UCAp , value and a UCAf value, respectively, The compressive-strength tests and UCA analyzer tests were performed in accordance with API Recommended Practice 10B, Further, shear-bond and Brazilian-tensile-strength tests were performed to determine shear strength and tensile strength values, respectively, for the different cement compositions. The shear-bond-strength tests were performed as described 15 in SPE 764 entitled "A Study of Cement Pipe Bonding" by L.G. Carter and G:W. Evans. The Brazilian-tensile-strength tests were performed in accordance with ASTNT C496-96. The results of the tests performed on each of the five compositions are shown in Table I below, TABLE I Shear- Brazilian 1' [CA 1 U CAr~ .Bond Tensile Slurry Sihia Type to 70 Bc psi) (pi Sr g Strength STength (:Mi) (psi) (P(psi) Strength Strength (psi) (psi) Slurry 30 nm 2:43 328 419 428 169 148.28 A particulate nano-silica Slurry 0 nm 5:00 500 481 402 51 14.72 B particulate nano-sil ica Slurry Amorphous 14:32 266 206 211 98 95,5 C silica Slurry Crystalline 120: 00+ 260 285 252 37.2 102 16 D Silica Sherry Colloidal 20:00+ 225 219 374 424 84.71 E Silica 20 EXAMPLE 2 [0041] Samples of Slurries A. C, D and E discussed above were also tested to determine various additional physical properties associated with the resulting set cements 14 and to confirm relative differences demonstrated above, While different instruments and calibration settings were used in the additional testing of the slurries, the test data indicates that relative differences between the different slurries are similar to those differences illustrated in Example 1. Indeed, as indicated above in Example 1, the respective test results 5 in Example 2 for the five different cements demonstrate that inclusion of particulate nano silica in the cement composition increases the strength of the resulting cement relative to cements resulting from inclusion of the other silica components that vere tested. [0042] Three samples for each of the three conventional cement slurries (Slurry C, Slurry D, and Slurry F) and four samples of Slurry A were tested to determine compressive 10 strength, Young's modtlus, and Poisson's ratio. The compressive-strength tests were performed in accordance with API Specification 10. It should be noted that the compressive strength measurements in Example I are different than those in Example 2 because different equipment and different calibrations were utilized. However, the relative differences between compressive strengths for each of the five slurries are similar. The Young's 15 modulus and Poisson's ratio were statically determined by means of compression testing using a load frame. The Young's modulus or modulus of elasticity for each sample was obtained by taking a ratio of a simple tension stress applied to each sample to a resulting strain parallel to the tension in that sample. The Poisson's ratio for each sample was determined by calculating a ratio of transverse strain to a corresponding axial strain resulting 20 from uniformly distributed axial stress below a proportional limit of each sample. The values determined for the three samples of each of the five different cement slurries are set toth below in Table 2. 15 TABLE 2 Compressive Young's Poissonis Slurry Sample Silica Type Strength Modulus Ratio (psi) 30 un Slurry A Sample I particulate 1257 2. 26E+05 ** nano-silica 30 nn Shurry A Sample 2 particulate 1189 2. 2+05 0.109 nano-silica 30 n~m Skurr~y A Samnpie 3 partic ulakte 1249 2,04E+105 0,092 30 nm Slurry A Sample 4 particulate 1275 2.131+05 0 110 nano-silica Amorphous S lrry C Sample 1 466 2531+05 0.064 Silica Slurry C Sample 2) 483 2.38E+05 0. 064 silica Slurry C Sample 3 5061240E+0 0,053 Sibca Crystalline.1050 .6 Slurry D Sample 2 397 50E+-1-05 0,063 CrystallineI Slurry D Sanple 3 378 1. 46105 0,060 Silica Colloidal Slurry E Sample 1 514 1.03E+05 0.063 Colloidal Slurry E Samplae 598 1 15E+05 0.072 Sibica Colloidal Slurry E Sample 3 627 1 23BE+05 0.071 Sibica [0043] The particular embodiments disclosed above are illustrative only, as the present invention may be susceptible to various modifications and alternative forms. However, it should be: understood that the invention is not intended to be limited to the 5 particular embodiments disclosed. Rather. the present invention is to cover all nodlifications, equivalents and alternatives falling with the scope and spirit of the present invention as defined by the: following appended claims. In addition, every range of values (of the fbrm, "from about a to about b," or, equivalently, "from approximately a to b," or, equivalently, "from approximately a-b") disclosed in the present Description of Specific 0 Embodiments is to be understood as referring to the power set (the set of all subsets) of the 16 - 17 respective ranges of values, and set for the every range encompassed within the broader range of value. The reference to any prior art in this specification is not, and should not be taken as, an acknowledgment or any form of suggestion that the prior art forms part of the common general knowledge.