Larry L Best

US Patent:

52516962, Oct 12, 1993

Filed:

Apr 6, 1992

Appl. No.:

7/863838

Inventors:

James R. Boone - Grand Prairie TX
Larry D. Best - Springtown TX
Ronnie D. Brown - North Richland Hills TX

International Classification:

E21B 4312
F04B 4900
F04B 4906

US Classification:

166250

Abstract:

A method and apparatus for Varying the speed of operations of an oil well pumping unit powered by a motor wherein variations in oil viscosity may be efficiently accommodated. An oil well pumping unit which includes a submersible pump actuated by means of a reciprocating string of sucker rods is monitored for both rod position and load present on the sucker rods. The oil well pumping unit is driven by an electric or gas motor through a controllable coupling and the speed of the oil well pumping unit is then varied, utilizing the controllable coupling, in response to variations in sucker rod load. As the lowering of the sucker rod is impeded by high viscosity oil, the load on the sucker rod decreases. This decrease in sucker rod load is utilized to decrease the speed of the oil well pumping unit by means of the controllable coupling to ensure that bridle separation does not occur. Additionally, increases in sucker rod load above a preselected maximum may also be detected and utilized to slow the operation of the oil well pumping unit to prevent damage to the sucker rods.