Low friction and high wear resistant sucker rod string
A sucker rod string is formed from sucker rods and sucker rod couplings. The sucker rod couplings are formed from a spinodally-hardened copper alloy comprising from about 8 to about 20 wt % nickel, and from about 5 to about 11 wt % tin, the remaining balance being copper, and having a sliding coefficient of friction of 0.4 or less when measured against carbon steel. The sucker rod string has low friction and improved pumping stroke, enhanced pumping capacity, and less load in the overall system.
1. A sucker rod string comprising a set of couplings, wherein the set of couplings includes a plurality of couplings made from a copper-nickel-tin alloy; and
wherein the copper-nickel-tin alloy comprises from about 8 to about 20 wt % nickel, and from about 5 to about 11 wt % tin, and has a sliding coefficient of friction of less than 0.4 when measured against carbon steel and a Charpy V-notch impact energy of at least 22 ft-lbs at room temperature.
2. The sucker rod string of claim 1 , wherein the plurality of couplings made from the copper-nickel-tin alloy is located in either a lower pump end of the sucker rod string, or an upper motor end of the sucker rod string, or a center section of the sucker rod string.
3. The sucker rod string of claim 1 , wherein at least 50% of the couplings in a lower pump end, an upper motor end, or a center section of the sucker rod string are made from the copper-nickel-tin alloy.
4. The sucker rod string of claim 1 , wherein the plurality of couplings made from the copper-nickel-tin alloy includes at least 5 couplings.
5. The sucker rod string of claim 1 , wherein at least 5% of the couplings in the set of couplings are made from the copper-nickel-tin alloy.
6. The sucker rod string of claim 1 , wherein the set of couplings includes (a) the plurality of couplings made from the copper-nickel-tin alloy; and (b) a plurality of non-copper couplings; and wherein the couplings made from the copper-nickel-tin alloy are alternated with the non-copper couplings.
7. The sucker rod string of claim 1 , wherein the copper-nickel-tin alloy has a sliding coefficient of friction of 0.3 or less when measured against carbon steel.
8. A method of extracting a fluid from a well, comprising:
operatively connecting a downhole pump to a motor using a sucker rod string;
wherein the sucker rod string comprises a set of couplings, wherein the set of couplings includes a plurality of couplings made from a copper-nickel-tin alloy; and
wherein the copper-nickel-tin alloy comprises from about 8 to about 20 wt % nickel, and from about 5 to about 11 wt % tin, and has a sliding coefficient of friction of less than 0.4 when measured against carbon steel and a Charm/V-notch impact energy of at least 22 ft-lbs at room temperature; and
operating the downhole pump using the sucker rod string to extract fluid from the well.
9. The method of claim 8 , wherein the well is a deviated well.
10. The method of claim 8 , wherein a pump stroke of the pump is increased by about 3% to about 40% compared to when the sucker rod string uses SM steel couplings.
11. The method of claim 8 , wherein fluid production of the well is increased by about 3% to about 40% compared to when the sucker rod string uses SM steel couplings.
12. The method of claim 8 , wherein average peak load is reduced by at least 5% compared to when the sucker rod string uses SM steel couplings.
13. The method of claim 8 , wherein run time is increased by at least 5% compared to when the sucker rod string uses SM steel couplings.
14. The method of claim 8 , wherein a continuous run time of the pump is at least one year.
15. The method of claim 8 , wherein the copper-nickel-tin alloy has a sliding coefficient of friction of 0.3 or less when measured against carbon steel.
16. A coupling for a sucker rod, comprising a spinodally-hardened copper-nickel-tin alloy comprising from about 8 to about 20 wt % nickel, and from about 5 to about 11 wt % tin, wherein the alloy has a 0.2% offset yield strength of at least 75 ksi, and has a sliding coefficient of friction of less than 0.4 when measured against carbon steel and a Charpy V-notch impact energy of at least 22 ft-lbs at room temperature.
17. The coupling of claim 16 , wherein the spinodally-hardened copper-nickel-tin alloy comprises about 14.5 wt % to about 15.5 wt % nickel, and about 7.5 wt % to about 8.5% tin, the remaining balance being copper.
18. The coupling of claim 16 , wherein the alloy has a 0.2% offset yield strength of at least 85 ksi.
19. The coupling of claim 16 , wherein the alloy has a sliding coefficient of friction of about 0.3 or less when measured against carbon steel.
20. A pump system comprising:
a downhole pump;
a power source for powering the downhole pump; and
a sucker rod string operatively connected to the downhole pump and the power source;
wherein the sucker rod string comprises:
at least a first rod and a second rod, each rod including an end having a pin with an external thread; and
a coupling joining the first rod and the second rod, the coupling including a core having a first end and a second end, each end containing an internal thread;
wherein the coupling comprises a spinodally-hardened copper-nickel-tin alloy comprising from about 8 to about 20 wt % nickel, and from about 5 to about 11 wt % tin, the remaining balance being copper, wherein the alloy has a 0.2% offset yield strength of at least 75 ksi, a sliding coefficient of friction of less than 0.4 when measured against carbon steel, and a Charpy V-notch impact energy of at least 22 ft-lbs at room temperature.