Tapered Spline Connection for Drill Pipe, Casing, and Tubing

Abstract

An apparatus comprises a first number of splines located near a first end of a first joint section and a second number of splines located near a second end of a second joint section. The first number of splines extends in an axial direction of the first joint section and spans a circumferential surface of the first joint section. Each of the first number of splines has a base, a tip, and a pair of flanks that extends from the base to the tip and forms an acute angle. Each of the first number of splines are configured to be received between adjacent pairs of splines in the second number of splines as the first end of the first joint section and the second end of the second joint section are joined.

What is claimed is: 
     
         1 . A drill pipe segment, comprising:
 a first end comprising a first joint section, said first joint section having at least one electrical connector;   a first number of splines located at said first joint section, the first number of splines disposed on a circumferential outer surface of the first joint section, and extending in a first axial direction towards the first end and outwardly in a first radial direction from the circumferential outer surface, each of the first number of splines having a base, a tip, and a pair of flanks extending from the base to the tip wherein the pair of flanks forms an acute angle, wherein the tips of the first number of splines are spaced from the first end of the first joint section, which defines a first cylindrical portion with an outer surface, and wherein the first number of splines extend outwardly from the outer surface of the first cylindrical portion;   wherein one spline of the first number of splines is a different size than the other splines of the first number of splines;   a second end comprising a second joint section, said second joint section having at least one electrical contact;   a second number of splines located at said second joint section, the second number of splines disposed on a circumferential inner surface of the second joint section and extending in a second axial direction towards the second end and inwardly in a second radial direction from the circumferential inner surface, each of the second number of splines having a base, a tip, and a pair of flanks extending from the base to the tip wherein the pair of flanks forms an acute angle, wherein the tips of the second number of splines are spaced from the second end of the second joint section, which defines a second cylindrical portion with an inner surface, and wherein the second number of splines extend inwardly from the inner surface of the second cylindrical portion;   wherein each of the first number of splines is configured to be received between a plurality of recessed areas defined by corresponding splines of a second joint section of another drill pipe segment;   wherein one recessed area of the plurality of recessed areas is a different size than the other recessed areas of the plurality of splines, and wherein the recessed area of the different size accommodates the spline of a different size of the other drill pipe segment;   a length of pipe between the first joint section and said second joint section;   wherein said first joint section, said length of pipe, and said second joint section are made of aluminum or an aluminum alloy;   a load ring threadingly engaged to threads spaced from said first end;   a coupling operatively interconnected to said length and adapted to engage said load ring; and   wherein said load ring and coupling are made of steel or a steel alloy.   
     
     
         2 . The drill pipe segment of  claim 1 , wherein the pair of flanks of said first number of splines forms a first spline angle; and
 wherein said flanks of said second number of splines forms a second spline angle.   
     
     
         3 . The drill pipe segment of  claim 2 , wherein the first spline angle and the second spline angle are about the same. 
     
     
         4 . The drill pipe segment of  claim 1 , wherein the first spline angle and the second spline angle are different. 
     
     
         5 . The drill pipe segment of  claim 2 , wherein the flanks of the first number of splines and the flanks of the second number of splines are curved. 
     
     
         6 . The drill pipe segment of  claim 2 , wherein the flanks of the first number of splines and the flanks of the second number of splines are approximated by a parabolic curve. 
     
     
         7 . The drill pipe segment of  claim 1 , wherein:
 the at least one electrical connector is positioned between bases of splines of the first number of splines; and   wherein the at least one electrical contacts is positioned on tips of splines of the second number of splines.   
     
     
         8 . The drill pipe segment of  claim 1 , wherein when the drill pipe segment is interconnected to another drill pipe segment, the tips located at the end of each of the first splines are spaced from the intersection of adjacent flanks of a second number of splines of the other drill pipe segment, and wherein the tips located at the end of each of the second splines are spaced from the intersection of adjacent flanks of the drill pipe segment. 
     
     
         9 . An apparatus, comprising:
 a first drill pipe segment having a first end comprising a first joint section and a second end comprising a second joint segment;   a second drill pipe segment having a third end comprising a third joint section and a fourth end comprising a fourth joint segment;   a first number of splines located near the first end of a first joint section, the first number of splines disposed on a circumferential outer surface of the first joint section, and extending in a first axial direction towards the first end and outwardly in a first radial direction from the circumferential outer surface, each of the first number of splines having a base, a tip, and a pair of flanks extending from the base to the tip wherein the pair of flanks forms an acute angle, wherein the first number of splines have first root radii at first interfaces between the first number of splines and the circumferential outer surface, and wherein a number of first edges of the first number of splines have a first rounded off portion;   a second number of splines located near the second end of a second joint section, the second number of splines disposed on a circumferential inner surface of the second joint section and extending in a second axial direction towards the second end and inwardly in a second radial direction from the circumferential inner surface, each of the second number of splines having a base, a tip, and a pair of flanks extending from the base to the tip wherein the pair of flanks forms an acute angle. wherein the second number of splines have second root radii at second interfaces between the second number of splines and the circumferential outer surface, and wherein a number of second edges of the second number of splines have a second rounded off portion;   a third number of splines located near the third end of a third joint section, the third number of splines disposed on a circumferential outer surface of the third joint section, and extending in a third axial direction towards the third end and outwardly in a third radial direction from the circumferential outer surface, each of the third number of splines having a base, a tip, and a pair of flanks extending from the base to the tip wherein the pair of flanks forms an acute angle, wherein the third number of splines have third root radii at third interfaces between the third number of splines and the circumferential outer surface, and wherein a number of third edges of the third number of splines have a third rounded off portion;   a fourth number of splines located near the fourth end of a fourth joint section, the fourth number of splines disposed on a circumferential inner surface of the fourth joint section and extending in a fourth axial direction towards the fourth end and inwardly in a fourth radial direction from the circumferential inner surface, each of the fourth number of splines having a base, a tip, and a pair of flanks extending from the base to the tip wherein the pair of flanks forms an acute angle. wherein the fourth number of splines have fourth root radii at fourth interfaces between the fourth number of splines and the circumferential outer surface, and wherein a number of fourth edges of the fourth number of splines have a fourth rounded off portion;   wherein each of the first number of splines is configured to be received between adjacent pairs of splines in the fourth number of splines as the first end of the first joint section and the fourth end of the second drill pipe segment are joined together to form a connection between the first joint section and the fourth joint section, wherein a gap remains between each tip of each of the first number of splines and corresponding portions of the flanks of the fourth number of splines when the first drill pipe segment and the second drill pipe segment are fully connected;   an orientation spline of the second number of splines having a size that is substantially different from other splines in the second number of splines wherein the size of the orientation spline is one of a wider size from other splines in the second number of splines; and a recessed area on the first joint section near the first end, the recessed area positioned between a pair of splines of the fourth number of splines, the recessed area adapted to receive the orientation spline, wherein the orientation spline and the recessed area maintain a particular orientation for the connection between the first drill pipe and the second drill pipe;   a first length of pipe between the first joint section and said second joint section;   a second length of pipe between the third joint section and said fourth joint section;   wherein said first joint section, said second joint section, said third joint section, and said fourth joint section, said first length of pipe, and said second length of pipe are made of aluminum or an aluminum alloy;   a load ring threadingly engaged to threads spaced from said first end;   a coupling operatively interconnected to said first length of pipe and adapted to engage said load ring; and   wherein said load ring and coupling are made of steel or a steel alloy.   
     
     
         10 . The apparatus of  claim 9 , wherein the orientation spline is a first orientation spline and the recessed area is a first recessed area further comprising:
 an additional orientation spline of the second number of splines having a size that is substantially different from other splines in the fourth number of splines; and   an additional recessed area on the first joint section near the first end, the additional recessed area positioned between a pair of splines of the fourth number of splines, the additional recessed area adapted to receive the orientation spline, wherein the additional orientation spline and the additional recessed area maintain a particular orientation for the connection between the first joint section and the fourth joint section.   
     
     
         11 . The apparatus of  claim 9 , wherein said orientation spline includes a second recessed area associated with an electrical connector, and the recessed area of said first joint section includes a second spline that is associated with an electrical connector having a size that is substantially different from the first number of splines, the second recessed area having a profile that corresponds with the second spline. 
     
     
         12 . An apparatus comprising:
 a first drill pipe segment having a first end comprising a first joint section and a second end comprising a second joint segment;   a second drill pipe segment having a third end comprising a third joint section and a fourth end comprising a fourth joint segment;   a first number of splines located near a first end of a first joint section, the first number of splines disposed on a circumferential outer surface of the first joint section, and extending in a first axial direction towards the first end and outwardly in a first radial direction from the circumferential outer surface, each of the first number of splines having a base, a tip, and a pair of flanks extending from the base to the tip wherein the pair of flanks forms an acute angle, wherein the first number of splines have first root radii at first interfaces between the first number of splines and the circumferential outer surface;   a second number of splines located near a second end of a second joint section, the second number of splines disposed on a circumferential inner surface of the second joint section and extending in a second axial direction towards the second end and inwardly in a second radial direction from the circumferential inner surface, each of the second number of splines having a base, a tip, and a pair of flanks extending from the base to the tip wherein the pair of flanks forms an acute angle, wherein the second number of splines have second root radii at second interfaces between the second number of splines and the circumferential outer surface;   a third number of splines located near a third end of a third joint section, the third number of splines disposed on a circumferential outer surface of the third joint section, and extending in a third axial direction towards the third end and outwardly in a third radial direction from the circumferential outer surface, each of the third number of splines having a base, a tip, and a pair of flanks extending from the base to the tip wherein the pair of flanks forms an acute angle, wherein the third number of splines have third root radii at third interfaces between the third number of splines and the circumferential outer surface;   a fourth number of splines located near a fourth end of a fourth joint section, the fourth number of splines disposed on a circumferential inner surface of the fourth joint section and extending in a fourth axial direction towards the fourth end and inwardly in a fourth radial direction from the circumferential inner surface, each of the fourth number of splines having a base, a tip, and a pair of flanks extending from the base to the tip wherein the pair of flanks forms an acute angle, wherein the fourth number of splines have fourth root radii at fourth interfaces between the fourth number of splines and the circumferential outer surface;   wherein each of the first number of splines is configured to be received between adjacent pairs of splines in the fourth number of splines of the first joint section and fourth joint section are joined to form a connection between the first drill pipe segment and the second drill pipe segment, wherein a gap remains between each tip of each of the first number of splines and corresponding portions of the flanks of the fourth number of splines when the first joint section and the second joint section are fully connected;   a first length of pipe between the first joint section and said second joint section;   a second length of pipe between the third joint section and said fourth joint section;   wherein said first joint section, said second joint section, said third joint section, and said fourth joint section, said first length of pipe, and said second length of pipe are made of aluminum or an aluminum alloy;   a load ring threadingly engaged to threads spaced from said first end;   a coupling operatively interconnected to said first length of pipe and adapted to engage said load ring; and   wherein said load ring and coupling are made of steel or a steel alloy.   
     
     
         13 . The apparatus of  claim 12 , wherein the pairs of flanks of each of the first number of splines are wedged between and seated on flanks of adjacent splines of the fourth number of splines as the first end of the first joint section and the fourth end of the fourth joint section are joined and wherein the coupling is tightened to wedge the first number of splines between adjacent pairs of splines in the fourth number of splines to a preconfigured force. 
     
     
         14 . The apparatus of  claim 12 , wherein each of the first number of splines and each of the fourth number of splines has a size that is substantially similar, so that the first joint section and the fourth joint section may be connected in a number of different orientations. 
     
     
         15 . The apparatus of  claim 12 , further comprising:
 a first number of electrical connectors positioned between bases of splines of the first number of splines;   a second number of electrical connectors positioned on tips of splines of the second number of splines, wherein the second number of electrical connectors are adapted to connect to the first number of electrical connectors when the first joint section and the second joint section are joined   a third number of electrical connectors positioned between bases of splines of the third number of splines;   a fourth number of electrical connectors positioned on tips of splines of the fourth number of splines, wherein the fourth number of electrical connectors are adapted to connect to the first number of electrical connectors when the first joint section and the fourth joint section are joined.   
     
     
         16 . The apparatus of  claim 12 , further comprising a filler positioned within the gap. 
     
     
         17 . The apparatus of  claim 12 , wherein the gaps have a length from about 3/32 in. to about 9/32 in.