Drill bit having an improved seal and lubrication method using same

TECHNICAL FIELD OF THE INVENTION

0001This invention relates, in general, to drill bits used for drilling a well that traverses a subterranean hydrocarbon bearing formation and, in particular, to an improved seal for a rotary drill bit than maintains lubricant within the drill bit and prevents the flow of drilling fluid into the bearing of the drill bit.

BACKGROUND OF THE INVENTION

0002Without limiting the scope of the present invention, its background will be described with reference to using rotary drill bits to drill a well that traverses a subterranean hydrocarbon bearing formation, as an example.

0003Rotary drill bits are commonly used to drill wells in the oil and gas well drilling industry as these rotary drill bit offers a satisfactory rate of penetration with a significant operational life in drilling most commonly encountered formations. Typically, a rotary drill bit includes a bit body having a threaded pin at its upper end adapted to be detachably secured to a drill string suspended from a drill rig. In addition, a rotary drill bit generally has a plurality of depending legs, typically three such legs, at the lower end of the body. The drill bit further includes a plurality of conical roller cutters having cutting elements thereon, with one roller cutter on each leg. Each leg typically includes a bearing for rotatably mounting each roller cutter thereon.

0004Sealed bearing type roller cutter bits further have a lubrication system including a reservoir holding a supply of lubricant. A passage in the bit body extends from the reservoir to the bearing to allow flow of lubricant to the bearing. A seal is disposed between the roller cutter and the bearing journal that holds lubricant in the bit. A diaphragm at the reservoir provides pressure compensation between the lubricant and the drilling fluid in the annulus between the bit and the wellbore.

0005In use, roller cutter drill bits are rotated in the wellbore on the end of a drill string that applies a relatively high downward force onto the drill bit. As the bits are rotated, the conical roller cutters rotate on the bearing journals thereby bringing the cutting elements on the roller cutters into engagement with the substrate at the bottom of the wellbore. The cutting elements drill through the substrate at the wellbore bottom by applying high point loads to the substrate to thereby cause the substrate to crack or fracture from the compression. A drilling fluid, commonly called drilling mud, passes under pressure from the surface through the drill string to the drill bit and is ejected from one or more nozzles adjacent to the roller cutters. The drilling fluid cools the drill bit and carries the cuttings up the wellbore annulus to the surface.

0006For cost-effective drilling, a worn drill bit needs to be replaced due to the reduced rate of drilling penetration for the worn bit. At a certain point, the cost of replacing the old drill bit with a new bit becomes equal to the cost of the drilling inefficiency, or in other words, the cost of the new bit plus the cost of rig time in tripping the drill string in and out of the wellbore is less than the cost of operating the worn bit. Unfortunately, once a drill bit is positioned in a wellbore, gathering reliable information regarding the operating condition, performance and remaining useful life of the drill bit becomes difficult. Typically, the decision by a drilling rig operator to replace a drill bit is a subjective one, based upon experience and general empirical data showing the performance of similar drill bits in drilling similar substrate formations. The rig operator's decision, however, as to when to replace a drill bit is often not the most cost effective because of the many factors affecting drilling performance beyond the condition and performance of the bit itself.

0007In addition, it is not uncommon for a drill bit to fail during the drilling operation. Bit failure may occur due to a variety of factors. For example, a bit may fail due to an improper application of the bit, such as by excessive weight on the drill bit from the drilling string, excessive rotational speed, using the wrong type of bit for substrate being drilled and the like. Regardless of the cause, the two most common types of bit failures are breakage of the cutting elements and bearing failure.

0008In the first mode, pieces of the cutting elements, which are typically either steel teeth or tungsten carbide inserts, are broken from the roller cutters. This breakage does not normally stop the drilling action but it does significantly reduce the rate of drilling penetration. In addition, the broken pieces are typically carried out of the wellbore by the circulating drilling fluid, thereby leaving the wellbore bottom clean for a replacement bit to continue extending the wellbore.

0009In the second mode of failure, once a bearing assembly has failed, continued use of the bit may result in the roller cutter separating from the bearing journal and remaining in the wellbore when the drill string is retrieved to the surface. The lost roller cutter must then be retrieved from the wellbore in a time-consuming and expensive fishing operation in which a special retrieval tool is tripped, in and out of the wellbore to retrieve the broken roller cutter.

0010In sealed bearing roller cutter bits, bearing failure is often the result of a seal failure that allows lubricant to flow out of the drill bit and drilling fluid, which contains abrasive particles, to flow into the bearing. Although less common, diaphragm failure has the same result as seal failure. In any event, bearing failure is almost always preceded by, or at least accompanied by, a loss of lubricant.

0011Therefore, a need has arisen for an improved seal for a sealed bearing roller cutter bit that can maintain the lubricant within the drill bit and prevent the flow of drilling fluid into the bearing. A need has also arisen for such a seal that has a high resistance to heat and abrasion, has a low coefficient of friction and does not significantly deform under load. Further, need has arisen for such a seal that is resistant to chemical interaction with hydrocarbons fluids encountered within the wellbore and that has a long useful life.

SUMMARY OF THE INVENTION

0012The present invention disclosed herein comprises a drill bit having an improved seal that can maintain the lubricant within the drill bit and prevent the flow of drilling fluid into the bearing. The seal of the present invention has a high resistance to heat and abrasion, has a low coefficient of friction and does not significantly deform under load. In addition, the seal of the present invention is resistant to chemical interaction with hydrocarbons fluids encountered within the wellbore and has a long useful life.

0013The drill bit of the present invention includes a drill bit body that is attached to a drill string at its upper end and has a plurality of journal pins on its lower end. Each of the journal pins has a bearing surface into which bearings are positioned. A rotary cutter is rotatably mounted on each journal pin. Each rotary cutter includes a bearing surface in a complementary relationship with the bearing surface of the respective journal pin such that the bearings maintain the rotary cutter and journal pin in the rotatable relationship relative to each other.

0014The drill bit body includes a pressure-compensated reservoir in fluid communication with the bearing surfaces of each journal pin and rotary cutter combination. The pressure-compensated reservoir has a lubricant therein that lubricates the bearings between the bearing surfaces. A diaphragm is positioned within the pressure-compensated reservoir. The diaphragm transmits pressure from the region surrounding the drill bit to the lubricant within the pressure-compensated reservoir. A seal element is positioned between each journal pin and rotary cutter. The seal elements retain the lubricant in the bearing surfaces and prevent fluids from exterior of the drill bit from entering the bearing surfaces. The seal elements may be any suitable seals including o-ring seals, d-seals, t-seals, v-seals, flat seals, lip seals and the like.

0015The diaphragm, the seal element or both may be constructed from a nanocomposite material including a polymer host material and a plurality of nanostructures. The polymer host material may be an elastomer such as nitrile butadiene (NBR) which is a copolymer of acrylonitrile and butadiene, carboxylated acrylonitrile butadiene (XNBR), hydrogenated acrylonitrile butadiene (HNBR) which is commonly referred to as highly saturated nitrile (HSN), carboxylated hydrogenated acrylonitrile butadiene, ethylene propylene (EPR), ethylene propylene diene (EPDM), tetrafluoroethylene and propylene (FEPM), fluorocarbon (FKM), perfluoroelastomer (FEKM) and the like.

0016The nanostructures of the nanocomposite may include nanoparticles having a scale in the range of approximately 0.1 nanometer to approximately 500 nanometers. The nanostructures may be formed from materials such as metal oxides, nanoclays, carbon nanostructures and the like. For example, the nanostructures may be formed from a silicon material such as polysilane resins, polycarbosilane resins, polysilsesquioxane resins and polyhedral oligomeric silsesquioxane resins. The polymer host material and the nanostructures may interact via interfacial interactions such as copolymerization, crystallization, van der Waals interactions and cross-linking interactions.

0017In another aspect, the present invention is directed to a method for lubricating a drill bit. The drill bit includes a drill bit body having at least one bearing and a rotary cutter rotatably attached to the drill bit body at the bearing, the method includes the steps of introducing a lubricant into a pressure-compensated reservoir in fluid communication with the bearing and retaining the lubricant within the drill bit with a seal element comprising a nanocomposite material including a polymer host material and a plurality of nanostructures.

BRIEF DESCRIPTION OF THE DRAWINGS

0018For a more complete understanding of the features and advantages of the present invention, reference is now made to the detailed description of the invention along with the accompanying figures in which corresponding numerals in the different figures refer to corresponding parts and in which:

0019<figref idref="DRAWINGS">FIG. 1</figref> is a schematic illustration of one type of rotary cone drill bit having improved seals in accordance with teachings of the present invention;

0020<figref idref="DRAWINGS">FIG. 2</figref> is a schematic illustration of another type of rotary cone drill bit having improved seals in accordance with teachings of the present invention that is disposed in a wellbore;

0021<figref idref="DRAWINGS">FIG. 3</figref> is a cross sectional view with portions broken away of a drill bit having improved seals in accordance with teachings of the present invention;

0022<figref idref="DRAWINGS">FIG. 4</figref> is a nanoscopic view of a nanocomposite material including a polymer host material and a nanostructure used in improved seals for a drill bit in accordance with teachings of the present invention;

0023<figref idref="DRAWINGS">FIG. 5</figref> depicts the structural formula of one embodiment of a silicon-based nanostructure used in improved seals for a drill bit in accordance with teachings of the present invention;

0024<figref idref="DRAWINGS">FIG. 6</figref> depicts the structural formula of a second embodiment of a silicon-based nanostructure used in improved seals for a drill bit in accordance with teachings of the present invention;

0025<figref idref="DRAWINGS">FIG. 7</figref> depicts the structural formula of a third embodiment of a silicon-based nanostructure used in improved seals for a drill bit in accordance with teachings of the present invention;

0026<figref idref="DRAWINGS">FIG. 8</figref> depicts the structural formula of a fourth embodiment of a silicon-based nanostructure used in improved seals for a drill bit in accordance with teachings of the present invention; and

0027<figref idref="DRAWINGS">FIG. 9</figref> is a nanoscopic view of a nanocomposite material including a polymer host material, a plurality of nanostructures and an additive used in improved seals for a drill bit in accordance with teachings of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

0028While the making and using of various embodiments of the present invention are discussed in detail below, it should be appreciated that the present invention provides many applicable inventive concepts which can be embodied in a wide variety of specific contexts. The specific embodiments discussed herein are merely illustrative of specific ways to make and use the invention, and do not delimit the scope of the present invention.

0029Referring initially to <figref idref="DRAWINGS">FIG. 1</figref>, therein is depicted a rotary cone drill bit of the type used in drilling a wellbore that traverses a subterranean hydrocarbon bearing formation that is schematically illustrated and generally designated <b>10</b>. Rotary cone drill bit <b>10</b> includes a plurality of cone-shaped rotary cutter assemblies <b>12</b> that are rolled around the bottom of a wellbore by the rotation of a drill string attached to drill bit <b>10</b>. Each rotary cutter assemblies <b>12</b> is rotatably mounted on a respective journal or spindle with a bearing system, sealing system and lubrication system disposed therebetween.

0030Drill bit <b>10</b>, includes bit body <b>14</b> having a tapered, externally threaded upper portion <b>16</b> which is adapted to be secured to the lower end of a drill string. Depending from body <b>14</b> are three support arms <b>18</b>, only two of which being visible in FIG. <b>1</b>. Each support arm <b>18</b> preferably includes a spindle or journal formed integrally with the respective support arm <b>18</b>. Each rotary cutter assembly <b>12</b> is rotatably mounted on a respective spindle. The spindles are preferably angled downwardly and inwardly with respect to bit body <b>14</b> and exterior surface <b>20</b> of the respective support arm <b>18</b> such that when drill bit <b>10</b> is rotated, rotary cutter assemblies <b>12</b> engage the bottom of the wellbore. For some applications, the spindles may also be tilted at an angle of zero to three or four degrees in the direction of rotation of drill bit <b>10</b>.

0031Rotary cutter assemblies <b>12</b> may include surface compacts or inserts <b>22</b> pressed into respective gauge face surfaces and protruding inserts <b>24</b> or milled teeth, which scrape and gouge against the sides and bottom of the wellbore under the downhole force applied through the associated drill string. The borehole debris created by rotary cutter assemblies <b>12</b> is carried away from the bottom of the wellbore by drilling fluid flowing from nozzles <b>26</b> adjacent to lower portion <b>28</b> of bit body <b>14</b>. The drilling fluid flow upwardly toward the surface through an annulus formed between drill bit <b>10</b> and the side wall of the wellbore.

0032Each rotary cutter assembly <b>12</b> is generally constructed and mounted on its associated journal or spindle in a substantially identical manner. Dotted circle <b>30</b> on exterior surface <b>20</b> of each support arm <b>18</b> represents an opening to an associated ball retainer passageway. The function of opening <b>30</b> and the associated ball retainer passageway will be discussed later with respect to rotatably mounting rotary cutter assemblies <b>12</b> on their respective spindle. Each support arm <b>18</b> includes a shirttail <b>32</b>.

0033Referring next to <figref idref="DRAWINGS">FIG. 2</figref>, therein is depicted a rotary cone drill bit that is generally designated <b>40</b>. Drill bit <b>40</b> is attached to the lower end of a drill string <b>42</b> and is disposed in wellbore <b>44</b>. An annulus <b>46</b> is formed between the exterior of drill string <b>42</b> and the wall <b>48</b> of wellbore <b>44</b>. In addition to rotating drill bit <b>40</b>, drill string <b>42</b> is used to provide a conduit for communicating drilling fluids and other fluids from the well surface to drill bit <b>40</b> at the bottom of wellbore <b>44</b>. Such drilling fluids may be directed to flow from drill string <b>42</b> to multiple nozzles <b>50</b> provided in drill bit <b>40</b>. Cuttings formed by drill bit <b>40</b> and any other debris at the bottom of wellbore <b>44</b> will mix with drilling fluids exiting from nozzles <b>50</b> and returned to the well surface via annulus <b>46</b>.

0034In the illustrated embodiment, drill bit <b>40</b> includes a one piece or unitary body <b>52</b> with upper portion <b>54</b> having a threaded connection or pin <b>56</b> adapted to secure drill bit <b>40</b> with the lower end of drill string <b>42</b>. Three support arms <b>58</b> are preferably attached to and extended longitudinally from bit body <b>52</b> opposite from pin <b>56</b>, only two of which are visible in FIG. <b>2</b>. Each support arm <b>58</b> preferably includes a respective rotary cutter assembly <b>60</b>. Rotary cutter assemblies <b>60</b> extend generally downwardly and inwardly from respective support arms <b>58</b>.

0035Bit body <b>52</b> includes lower portion <b>62</b> having a generally convex exterior surface <b>64</b> formed thereon. The dimensions of convex surface <b>64</b> and the location of rotary cutter assemblies <b>60</b> are selected to optimize fluid flow between lower portion <b>62</b> of bit body <b>52</b> and rotary cutter assemblies <b>60</b>. The location of each rotary cutter assembly <b>60</b> relative to lower portion <b>62</b> may be varied by adjusting the length of support arms <b>58</b> and the spacing of support arms <b>58</b> on the exterior of bit body <b>52</b>.

0036Rotary cutter assemblies <b>60</b> may further include a plurality of surface compacts <b>66</b> disposed in gauge face surface <b>68</b> of each rotary cutter assembly <b>60</b>. Each rotary cutter assembly <b>60</b> may also include a number of projecting inserts <b>70</b>. Surface compacts <b>66</b> and inserts <b>70</b> may be formed from various types of hard materials depending on anticipated downhole operating conditions. Alternatively, milled teeth may be formed as an integral part of each rotary cutter assembly <b>60</b>.

0037Each support arm <b>58</b> also comprises a flow channel <b>72</b> to aid removal of cuttings and other debris from wellbore <b>44</b>. Flow channels <b>72</b> are disposed on exterior surface <b>74</b> of support arm <b>58</b>. Flow channels <b>72</b> may be formed in each support arm <b>58</b> by a machining operation. Flow channels <b>72</b> may also be formed during the process of forging the respective support arm <b>58</b>. After support arms <b>58</b> have been forged, flow channels <b>72</b> may be further machined to define their desired configuration.

0038Each support arm <b>58</b> includes shirttail <b>76</b> with a layer of selected hardfacing materials covering shirttail portion <b>78</b>. Alternatively, one or more compacts or inserts may be disposed within shirttail portions <b>78</b> to protect shirttail portions <b>78</b> from abrasion, erosion and wear. Dotted circle <b>80</b> on exterior surface <b>74</b> of each support arm <b>58</b> represents an opening to an associated ball retainer passageway.

0039Referring now to <figref idref="DRAWINGS">FIG. 3</figref>, therein is depicted a cross sectional view of a portion of a rotary cone drill bit that is generally designated <b>100</b>. Drill bit <b>100</b> has support arms <b>102</b> and rotary cutter assemblies <b>104</b>, only one of each being visible in FIG. <b>3</b>. Drill bit <b>100</b> includes a one piece or unitary bit body <b>106</b> that is substantially similar to previously described bit body <b>52</b> except for lower portion <b>108</b> which has a generally concave exterior surface <b>110</b> formed thereon. The dimensions of concave surface <b>110</b> and the location of rotary cutter assemblies <b>104</b> may be selected to optimize fluid flow between lower portion <b>108</b> of bit body <b>106</b> and rotary cutter assemblies <b>104</b>.

0040Rotary cutter assemblies <b>104</b> of drill bit <b>100</b> is mounted on a journal or spindle <b>112</b> projecting from respective support arms <b>102</b>. In addition, a bearing system is used to rotatably mount rotary cutter assemblies <b>104</b> on respective support arms <b>102</b>. More specifically, each rotary cutter assemblies <b>104</b> includes a generally cylindrical cavity <b>114</b> which has been sized to receive spindle or journal <b>112</b> therein. Each rotary cutter assemblies <b>104</b> and its respective spindle <b>112</b> have a common longitudinal axis <b>116</b> which also represents the axis of rotation for rotary cutter assemblies <b>104</b> relative to its associated spindle <b>112</b>. Each rotary cutter assemblies <b>104</b> is retained on its respective journal <b>112</b> by a plurality of ball bearings <b>118</b>. Ball bearings <b>118</b> are inserted through opening <b>120</b> in exterior surface <b>122</b> and ball retainer passageway <b>124</b> of the associated support arm <b>102</b>. Ball races <b>126</b>, <b>128</b> are formed respectively in the interior of cavity <b>114</b> of the associated rotary cutter assembly <b>104</b> and the exterior of journal <b>112</b>.

0041Ball retainer passageway <b>124</b> is connected with ball races <b>126</b>, <b>128</b>, such that ball bearings <b>118</b> may be inserted therethrough to form an annular array within ball races <b>126</b>, <b>128</b> to prevent disengagement of rotary cutter assembly <b>104</b> from its associated journal <b>112</b>. Ball retainer passageway <b>124</b> is subsequently plugged by inserting a ball plug retainer (not pictured) therein. A ball plug weld (not pictured) is preferably formed within each opening <b>120</b> to provide a fluid barrier between ball retainer passageway <b>124</b> and the exterior of each support arm <b>102</b> to prevent contamination and loss of lubricant from the associated sealed lubrication system.

0042Each support arm <b>102</b> preferably includes lubricant cavity or lubricant reservoir <b>130</b> having a generally cylindrical configuration. Lubricant cap <b>132</b> is disposed within one end of lubricant cavity <b>130</b> to prevent undesired fluid communication between lubricant cavity <b>130</b> and the exterior of support arm <b>102</b>. Lubricant cap <b>132</b> includes a flexible, resilient diaphragm <b>134</b> that closes lubricant cavity <b>130</b>. Cap <b>132</b> covers diaphragm <b>134</b> and defines a chamber <b>136</b> to provide a volume into which diaphragm <b>134</b> can expand. Cap <b>132</b> and diaphragm <b>134</b> are retained within lubricant cavity <b>130</b> by retainer <b>138</b>.

0043A lubricant passage <b>140</b> extends through support arm <b>102</b> such that lubricant cavity <b>130</b> is in fluid communication with ball retainer passageway <b>124</b>. Ball retainer passageway <b>124</b> provides fluid communication with internal cavity <b>114</b> of the associated rotary cutter assembly <b>104</b> and the bearing system disposed between the exterior of spindle <b>112</b> and the interior of cavity <b>114</b>. Upon assembly of drill bit <b>100</b>, lubricant passage <b>140</b>, lubricant cavity <b>130</b>, any available space in ball retainer passageway <b>124</b> and any available space between the interior surface of cavity <b>114</b> and the exterior of spindle <b>112</b> are filled with lubricant through an opening (not pictured) in each support arm <b>102</b>. The opening is subsequently sealed after lubricant filling.

0044The pressure of the external fluids outside drill bit <b>100</b> may be transmitted to the lubricant contained in lubricant cavity <b>130</b> by diaphragm <b>134</b>. The flexing of diaphragm <b>134</b> maintains the lubricant at a pressure generally equal to the pressure of external fluids outside drill bit <b>100</b>. This pressure is transmitted through lubricant passage <b>140</b>, ball retainer passageway <b>124</b> and internal cavity <b>114</b> to expose the inward face of seal element <b>142</b> to pressure generally equal to the pressure of the external fluids. More specifically, seal element <b>142</b> is positioned within a seal retaining groove <b>144</b> within cavity <b>114</b> to establish a fluid barrier between cavity <b>114</b> and journal <b>112</b>. Seal element <b>142</b> may be an o-ring seal, a d-seal, a t-seal, a v-seal, a flat seal, a lip seal or the like and equivalents thereof that are suitable for establishing the required fluid barrier between cavity <b>114</b> and journal <b>112</b>. In addition, more than one seal or a combination seal and backup ring may be positioned within one or more seal retaining grooves or otherwise between cavity <b>114</b> and journal <b>112</b>.

0045As diaphragm <b>134</b> and seal element <b>142</b> must operate at the pressure and temperature conditions that prevail downhole, maintain lubricant within the drill bit, prevent the flow of drilling fluid into the bearing of the drill bit and have a long useful life, it is important that diaphragm <b>134</b> and seal, element <b>142</b> be resistant to hydrocarbons fluids and other chemical compositions found within oil wells and have high heat resistance. In addition, it is important that seal element <b>142</b> have high abrasion resistance, low rubbing friction and not readily deform under the pressure and temperature conditions in a well.

0046Diaphragm <b>134</b> and seal element <b>142</b> of the present invention are preferably formed from a polymeric material that, over a range of temperatures, is capable of recovering substantially in shape and size after removal of a deforming force, i.e., a polymeric material that exhibits certain physical and mechanical properties relative to elastic memory and elastic recovery. Accordingly, diaphragm <b>134</b> and seal element <b>142</b> of the present invention are preferably formed from an elastomeric material. In particular, seal element <b>142</b> of the present invention is preferably formed from an elastomeric material that is produced by a curing method that involves compounding or mixing the base polymer with various additive or agents such as graphite, a peroxide curing agent, furnace black, zinc oxide, magnesium oxide, antioxidants, accelerators, plasticizers, processing aids or the like and combinations thereof which modify various properties of the base polymer.

0047More specifically, seal element <b>142</b> may be formed from a nitrile elastomer such as nitrile butadiene (NBR) which is a copolymer of acrylonitrile and butadiene, carboxylated acrylonitrile butadiene (XNBR), hydrogenated acrylonitrile butadiene (HBR) which is commonly referred to as highly saturated nitrile (HSN), carboxylated hydrogenated acrylonitrile butadiene and the like. Seal, element <b>142</b> may also be formed from other elastomers such as ethylene propylene (EPR), ethylene propylene diene (EPDM), tetrafluoroethylene and propylene (FEPM), fluorocarbon (FKM), perfluoroelastomer (FEKM) or the like and equivalents thereof.

0048For example, the use of an HSN elastomer provides seal element <b>142</b> with the properties of elasticity, good chemical resistance, high mechanical strength and good resistance to abrasion at elevated temperatures as well as low coefficient of friction and excellent wear resistance. As compared with standard nitrile elastomers, HSN elastomers are hydrogenated to reduce the number of carbon-carbon double bonds. The hydrogenation process preferable eliminates between 96% and 99.5% of the double bonds in the nitrile. The removal of the carbon-carbon double bonds reduces the reaction of agents such as hydrocarbons, oxygen, hydrogen sulfide and ozone with the elastomer. Attack by such agents can reduce the tensile strength, elongation and compression set resistance of the elastomer composition.

0049While the additives listed above tend to improve certain properties when compounded or mixed with the base polymer of seal element <b>142</b>, the improvement in one property tends to be counteracted by a reduction in the performance envelope of another property. For example, compounding the base polymer with an additive may result in an increase in the temperature stability of the base polymer but may also result in a reduction in the abrasion resistance of the base polymer or vice versa.

0050Seal element <b>142</b> of the present invention, however, overcomes these property trade off problems by integrating nanomaterials into the base polymer either instead of or in addition to other additives. As seen in <figref idref="DRAWINGS">FIG. 4</figref>, a nanocomposite material forming a diaphragm or a seal element of the present invention is nanoscopically depicted and generally designated <b>150</b>. Nanocomposite material <b>150</b> includes a polymer host material <b>152</b> includes multiple polymers, such as polymers <b>154</b>, <b>156</b>, <b>158</b> and a plurality of nanostructures such as the depicted nanostructure <b>160</b>. Polymer host material <b>152</b> exhibits microporocity as represented by a plurality of regions of free volume, such as region <b>162</b>. In the illustrated embodiment, nanostructure <b>160</b> is positioned within free volume region <b>162</b>.

0051Nanostructure <b>160</b> structurally and chemically complements the microporocity of polymer host material <b>152</b>. More specifically, as nanostructure <b>160</b> has a greater surface area than polymer host material <b>152</b>, due to the nano-size and nano-volume of nanostructure <b>160</b>, nanostructure <b>160</b> is integrated with polymer host material <b>152</b> and forms interfacial interactions with polymer host material <b>152</b> at region <b>162</b>. The interfacial interactions, including copolymerization, crystallization, van der Waals interactions and cross-linking interactions, are formed between nanostructure <b>160</b> and multiple polymers <b>154</b>, <b>156</b>, <b>158</b> to not only improve the tensile strength, compression set and temperature stability of polymer host material <b>152</b>, but also the extrusion resistance, explosive decompression resistance and abrasion resistance of host polymer material <b>152</b>, thereby resulting in an extended life for the diaphragms and seal elements of the present invention.

0052Preferably, nanostructure <b>160</b> is integrated with polymer host material <b>152</b> prior to curing. In one embodiment, nanostructure <b>160</b> is integrated into polymer host material <b>152</b> by adding or blending nanostructure <b>160</b> in a preceramic state with polymer host material <b>152</b> such that when nanostructure <b>160</b> is heated above its decomposition point, nanostructure <b>160</b> converts into a ceramic. Alternatively, nanostructure <b>160</b> may be integrated with polymer host material <b>152</b> after curing using a deposition process such as spraying.

0053Nanostructure <b>160</b> comprises nanoparticles having a scale in the range of approximately 0.1 nanometers to approximately 500 nanometers. Nanostructure <b>160</b> may be formed by a process including sol-gel synthesis, inert gas condensation, mechanical alloying, high-energy ball milling, plasma synthesis, electrodeposition or the like. Nanostructure <b>160</b> may include metal oxides, nanoclays, carbon nanostuctures and the like.

0054Metal oxide nanoparticles include oxides of zinc, iron, titanium, magnesium, silicon, aluminum, cerium, zirconium or the like and equivalents thereof, as well as mixed metal compounds such as indium-tin and the like. In one embodiment, a plasma process is utilized to form metal oxide nanoparticles having a narrow size distributions, nonporous structures and nearly spherical shapes. Nanoclays are naturally occurring, plate-like clay particles such as montmorillonite (MMT) nanoclay. In one embodiment, the nanoclays are exfoliated in the polymer host via a plastic extrusion process. Carbon nanostuctures include carbon nanotubes, carbon nanofibers (CNF), nanocarbon blacks and calcium carbonates.

0055In one embodiment, nanostructure <b>160</b> may be formed from polysilane resins (PS), as depicted in <figref idref="DRAWINGS">FIG. 5</figref>, polycarbosilane resins (PCS), as depicted in <figref idref="DRAWINGS">FIG. 6</figref>, polysilsequioxane resins (PSS), as depicted in <figref idref="DRAWINGS">FIG. 7</figref>, or polyhedral oligomeric silsesquioxane resins (POSS), as depicted in <figref idref="DRAWINGS">FIG. 8</figref>, as well as monomers, polymers and copolymers thereof or the like and equivalents thereof. In the formulas presented in <figref idref="DRAWINGS">FIGS. 5-8</figref>, R represent a hydrogen or an alkane, alkenyl or alkynl hydrocarbons, cyclic or linear, with 1-28 carbon atoms, substituted hydrocarbons R—X, aromatics Ar and substituted aromatics Ar—X where X represents halogen, phosphorus or nitrogen containing groups. The incorporation of halogen or other inorganic groups such as phosphates and amines directly into onto these nanoparticles can afford additional improvements to the mechanical properties of the material. For example, the incorporation of halogen group can afford additional heat resistance to the material. These nanostructures may also include termination points, i.e., chain ends, that contain reactive or nonreactive functionalities such as silanols, esters, alcohols, amines or R groups.

0056Referring next to <figref idref="DRAWINGS">FIG. 9</figref>, a nanocomposite material for use in a seal element of the present invention is nanoscopically depicted and generally designated <b>170</b>. As described above, one or more additives may be compounded or mixed with the base polymer of the seal element to modify and enhance desirable seal properties. Use of nanostructures in combination with these additives can further enhance desirable seal properties. As illustrated, a polymer interphase region <b>172</b> is defined by polymer host material. An additive <b>174</b> is associated with polymer interphase region <b>172</b>. Nanostructures <b>176</b>-<b>184</b> stabilize and reinforce interphase region <b>172</b> of nanocomposite <b>170</b> and, in particular, nanostructures <b>176</b>-<b>184</b> reinforce the polymers and complement additive <b>174</b> by strengthening the bonding between the polymers and additive <b>174</b>.

0057While this invention has been described with reference to illustrative embodiments, this description is not intended to be construed in a limiting sense. Various modifications and combinations of the illustrative embodiments as well as other embodiments of the invention, will be apparent to persons skilled in the art upon reference to the description. It is, therefore, intended that the appended claims encompass any such modifications or embodiments.