Fatigue resistant coiled tubing

A length of metal tubing formed from strips of metal welded together, said metal tubing comprising:

• a composite strip of metal having a longitudinal axis and parallel longitudinal edges, which composite strip is formed into a tubular form, said longitudinal edges being welded to each other to create the metal tubing;
• and
• wherein said composite strip comprises a first strip of metal material having an outer surface, a trailing end, and a trimmed leading end, said trimmed leading end having a bias cut profile beginning at a longitudinal edge of the first strip, said bias cut profile beginning with a first beta angle directed away from the trailing end of the first strip, as measured on the outer surface of the first strip from a first transverse plane perpendicular to the longitudinal axis of the composite strip, said bias cut profile forming a continuous cut that transitions from the first beta angle to an alpha angle which is smaller than the first beta angle and directed away from the trailing end of the first strip, as measured on the outer surface of the first strip from a second transverse plane perpendicular to the longitudinal axis of the composite strip, and then transitions from the alpha angle to a second beta angle which is larger than the first alpha angle and directed away from the trailing end of the first strip, as measured on the outer surface of the first strip from a third transverse plane perpendicular to the longitudinal axis of the composite strip, and terminates at an opposite longitudinal edge of the first strip to form a trimmed leading end of the first strip, and
• a second strip of metal material having an outer surface, a leading end and a trimmed trailing end matching the trimmed leading end of the first strip, said trimmed trailing end having a bias cut profile beginning at a longitudinal edge of the second strip, said bias cut profile beginning with the first beta angle directed towards the leading end of the second strip, as measured on the outer surface of the second strip from a first transverse plane perpendicular to the longitudinal axis of the composite strip, said bias cut profile forming a continuous cut that transitions from the first beta angle to the alpha angle which is smaller than the first beta angle and directed toward the leading end of the second strip, as measured on the outer surface of the second strip from a second transverse plane perpendicular to the longitudinal axis of the composite strip, and then transitions from the alpha angle to the second beta angle which is larger than the first alpha angle and directed towards the leading end of the second strip, as measured on the outer surface from a third transverse plane perpendicular to the longitudinal axis of the composite strip, and terminates at an opposite longitudinal edge of the second strip to form a trimmed trailing end of the second strip, and
• wherein the trimmed leading end of the first strip is welded to the trimmed trailing end of the second strip.

A method of manufacturing a continuous length of coiled tubing, said method comprising:

• manufacturing a length of metal tubing comprising:
• providing a first strip of metal material having a surface, a nominal width, a leading end, and a trailing end;
• providing a second strip of metal material having a surface, substantially the same nominal width as the first strip, a leading end, and a trailing end;
• trimming the leading end of the first strip of metal material with a bias cut profile beginning at a longitudinal edge of the first strip, said bias cut profile beginning with a first beta angle directed away from the trailing end of the first strip, as measured on the surface of the first strip from a first transverse plane perpendicular to a longitudinal axis of the first strip, said bias cut profile forming a continuous cut that transitions from the first beta angle to an alpha angle which is smaller than the first beta angle and directed away from the trailing end of the first strip as measured on the surface of the first strip from a second transverse plane perpendicular to the longitudinal axis of the first strip, and then transitions from the alpha angle to a second beta angle which is larger than the first alpha angle and directed away from the trailing end of the first strip, as measured on the surface of the first strip from a third transverse plane perpendicular to the longitudinal axis of the first strip, and terminates at an opposite longitudinal edge of the first strip to form a trimmed leading end;
• trimming the trailing end of the second strip of metal material with a bias cut profile matching the trimmed leading end of the first strip, said bias cut profile beginning at a longitudinal edge of the second strip, said bias cut profile beginning with the first beta angle directed toward the leading end of the second strip, as measured on the surface of the second strip from a first transverse plane perpendicular to a longitudinal axis of the second strip, said bias cut profile forming a continuous cut that transitions from the first beta angle to the alpha angle which is smaller than the first beta angle and directed towards the leading end of the second strip, as measured on the surface of the second strip from a second transverse plane perpendicular to the longitudinal axis of the second strip, and then transitions from the alpha angle to the second beta angle which is larger than the alpha angle and directed towards the leading end of the second strip, as measured on the surface of the second strip from a third transverse plane perpendicular to the longitudinal axis of the second strip, and terminates at an opposite longitudinal edge of the second strip to form a trimmed trailing end;
• welding the trimmed leading end of the first strip to the trimmed trailing end of the second strip to form a composite strip with parallel longitudinal edges and substantially a uniform nominal width over its length;
• forming the composite strip into a tubular shape with the parallel longitudinal edges of the composite strip positioned adjacent to each other;
• welding the longitudinal edges of the composite strip together to create the length of metal tubing;
• welding a plurality of the lengths of tubing together end to end thereby forming a continuous string of tubing;
• and
• spooling the continuous string of tubing onto a spool thereby forming a coiled tubing string.

A method of using a continuous length of a coiled tubing in a wellbore, said method comprising:

• manufacturing a length of metal tubing comprising:
• providing a first strip of metal material having a surface, a nominal width, a leading end, and a trailing end;
• providing a second strip of metal material having a surface, substantially the same nominal width as the first strip, a leading end, and a trailing end;
• trimming the leading end of the first strip of metal material with a bias cut profile beginning at a longitudinal edge of the first strip, said bias cut profile beginning with a first beta angle directed away from the trailing end of the first strip, as measured on the surface of the first strip from a first transverse plane perpendicular to a longitudinal axis of the first strip, said bias cut profile forming a continuous cut that transitions from the first beta angle to an alpha angle which is smaller than the first beta angle and directed away from the trailing end of the first strip as measured on the surface of the first strip from a second transverse plane perpendicular to the longitudinal axis of the first strip, and then transitions from the alpha angle to a second beta angle which is larger than the first alpha angle and directed away from the trailing end of the first strip, as measured on the surface of the first strip from a third transverse plane perpendicular to the longitudinal axis of the first strip, and terminates at an opposite longitudinal edge of the first strip to form a trimmed leading end;
• trimming the trailing end of the second strip of metal material with a bias cut profile matching the trimmed leading end of the first strip, said bias cut profile beginning at a longitudinal edge of the second strip, said bias cut profile beginning with the first beta angle directed toward the leading end of the second strip, as measured on the surface of the second strip from a first transverse plane perpendicular to a longitudinal axis of the second strip, said bias cut profile forming a continuous cut that transitions from the first beta angle to the alpha angle which is smaller than the first beta angle and directed towards the leading end of the second strip, as measured on the surface of the second strip from a second transverse plane perpendicular to the longitudinal axis of the second strip, and then transitions from the alpha angle to the second beta angle which is larger than the alpha angle and directed towards the leading end of the second strip, as measured on the surface of the second strip from a third transverse plane perpendicular to the longitudinal axis of the second strip, and terminates at an opposite longitudinal edge of the second strip to form a trimmed trailing end;
• welding the trimmed leading end of the first strip to the trimmed trailing end of the second strip to form a composite strip with parallel longitudinal edges and substantially a uniform nominal width over its length;
• forming the composite strip into a tubular shape with the parallel longitudinal edges of the composite strip positioned adjacent to each other;
• welding the longitudinal edges of the composite strip together to create the length of metal tubing;
• welding a plurality of the lengths of tubing together end to end thereby forming a continuous string of tubing;
• spooling the continuous string of tubing onto a spool thereby forming a continuous coiled tubing string;
• positioning the spool with the coiled tubing strings pooled thereon proximal to a wellbore;
• disposing a distal end of the coiled tubing string into the upper end of the wellbore;
• unspooling portions of the continuous coiled tubing string from the spool and simultaneously lowering the distal end of the coiled tubing string into the wellbore;
• and
• pumping fluid into the proximal end of the coiled tubing string and through the coiled tubing string and through the distal end of the tubing string disposed in the wellbore.