US 2006/0125234 A1 · Hollow sucker rod connection with second torque shoulder

Abstract

An elongated drive string assembly comprising a plurality of hollow sucker rods and a connecting elements with an axis, connected together and between a drive head located at the surface of an oil well and a rotary pump located deep down hole in an oil well. Each hollow sucker rod has at least a first end comprising an internal female threaded surface engaging an external male threaded surface on a connecting element, such as a nipple. In order to further optimize the stress distribution between the elements, frustro-conical, non-symmetrical threads with a differential diametral taper are used. Preferably two torque shoulders with a maximized mean diameter and cross-sectional area are used to resist storing reactive torque in the drive string. The nipple free end defines a second torque shoulder that adds to the torque transmission during make-up while also defining a small seal at that free end to decrease corrosion erosion problems. This overall configuration ensures high yield torque, high shear strength, lowered stress concentration and a surprising resistance to storing reactive torque, which minimizes dangerous backspin when power to the sucker rod string is interrupted.

Claims17

Dependent claims

the free first ends of each hollow sucker rod further comprising a pair of annular torque shoulders engaging an annular torque shoulder on a connecting element, and being characterized in that, for an outside diameter of the connecting element (DEN), an internal diameter (DIN1) of the connecting element, and a diameter of a first torque shoulder on the connecting element (DHT1), the following ratios are maintained:
Range
Diameter Ratios
Min.
Max.
DHT1/DEN
0.7
0.9
DIN1/DEN
0.2
0.6
DIN1/DHT1
0.3
0.7

11 more elements

An elongated drive string assembly comprising a plurality of hollow sucker rods and connecting elements with an axis, connected together and between a drive head located at the surface of an oil well and a rotary pump located deep down the oil well, wherein at least one hollow sucker rod has a first end comprising an internal female threaded surface engaging an external male threaded surface on at least one connecting element, wherein said threads are frusto-conical and non-symmetrical, but differential in diametral taper to each other;

the first end of said at least one hollow sucker rod further comprising an annular torque shoulder that is engaging an annular torque shoulder on said at least one connecting element and being characterized in that, for an outside diameter of the connecting element (DEN), inner bore diameters (DIN1, DIN2) of the connecting element, a diameter of a first torque shoulder on the connecting element (DHT1) and a diameter of a second torque shoulder on the free end of the connecting element (DHT2), the following ratios are maintained:
Range
Diameter Ratios
Min.
Max.
DHT1/DEN
0.7
0.9
DIN1/DEN
0.20
0.60
DIN1/DHT1
0.30
0.70
DIN2/DHT2
0.67
0.92
wherein said at least one connector element is a separate nipple having said male threaded surface on at least one free end of that nipple and a central section defining said engaging torque shoulder, and said male threaded surface of said nipple free end comprising complete threads, said nipple free end further comprises a portion that is adapted to engage against an inner surface of the rod, so as to define said second torque shoulder.

15 more elements

An elongated drive string assembly comprising a plurality of hollow sucker rods and connecting elements with an axis, connected together and between a drive head located at the surface of an oil well and a rotary pump located deep down the oil well, wherein at least one hollow sucker rod has a first end comprising an internal female threaded surface engaging an external male threaded surface on at least one connecting element, wherein said threads are modified buttress threads with a thread pitch of 6-8 threads per inch which are differential in diametral taper to each other;

the first end of said at least one hollow sucker rod further comprising an annular torque shoulder that is engaging an annular torque shoulder on said at least one connecting element and being characterized in that, for an outside diameter of the connecting element (DEN), internal diameters (DIN1, DIN2) of the connecting element, and a diameter of a first torque shoulder on the connecting element (DHT1) and a diameter of a second torque shoulder on the free end of the connecting element (DHT2), and the following ratios are maintained:
Range
Diameter Ratios
Min.
Max.
DHT1/DEN
0.7
0.9
DIN1/DEN
0.2
0.6
DIN1/DHT1
0.3
0.7
DIN2/DHT2
0.67
0.92
wherein those hollow sucker rods located proximate to each extreme end of the string have a plurality of holes extending through wall sections of those rods so as to enable fluid flowing outside of those rods to also flow within the inner bore of the drive string and between the extreme ends of said elongated drive string.

15 more elements

Dependencies are inferred from the claim text.

Hollow sucker rod connection with second torque shoulder

Life of this patent

Hollow sucker rod connection with second torque shoulder

Life of this patent

Abstract

Claims17