Method of using a polished rod transducer

A method for determining absolute load on a polished rod of a pumping system wherein the rod extends down a borehole to a downhole pump and the rod is reciprocated by a surface unit to cause the downhole pump to lift fluid up through the borehole, the method comprising the steps of:

• measuring changes in load on said polished rod during at least one pump cycle by detecting changes in diameter of said polished rod,
• said changes in diameter being determined by coupling a transducer to opposite longitudinal sides of said rod by applying a compressive force to said rod by said transducer at a single point along the length of said rod,
• determining the position of said polished rod by collecting position related information during said step of measuring changes in load on said polished rod,
• generating a downhole card by use of said measured changes in load, said position related information and known physical configuration of said rod,
• applying an offset value to said downhole card to shift said downhole card to have a predetermined minimum pump load,
• generating a surface card by use of said measured changes in said load on said polished rod and said determined position of said polished rod, and
• adjusting said surface card by said offset value to produce an absolute value surface card.

A method for determining absolute load on a downhole pump of a pumping system wherein a rod extends from the surface down a borehole to the downhole pump and the rod is reciprocated by a surface unit to cause the downhole pump to lift fluid up through the borehole, the method comprising the steps of:

• coupling a transducer to opposite longitudinal sides of said rod by applying a compressive force to said rod by said transducer, at a single point along the length of said rod wherein said compressive force is applied in a direction normal to the axis of said rod,
• deforming said transducer in response to applying said compressive force to said rod,
• generating a signal by said transducer in response to said compressive force applied by said transducer wherein said compressive force varies in response to changes in axial load on said rod,
• determining the position of said rod by collecting position related data during at least one cycle of said pump,
• generating a downhole card by use of said signal produced by said transducer, said position related data and a known physical configuration of said rod, and
• applying an offset value to said downhole card to shift said downhole card to have a minimum pump load of approximately zero to produce a downhole card representing absolute load on said downhole pump.

A method for acquiring and displaying data associated with axial loads on a polished rod of a pumping system wherein the rod extends down a borehole to a downhole pump and the rod is reciprocated by a surface unit to cause the downhole pump to lift fluid up through the borehole, the method comprising the steps of:

• securing a transducer to said polished rod by applying a transverse compressive force on said rod by said transducer at a single point along the length of said rod wherein said compressive force deforms said transducer and wherein a change is said compressive force is a function of the axial lead on said rod and wherein said transducer produces an output signal corresponding to the axial loads on said rod,
• digitizing said output signal to produce a set of digitized rod change in axial loading dam,
• storing said axial lead data, and
• displaying said set of data representing change in axial lead on said polished rod as a waveform as a function of time on a screen.

A method for acquiring and displaying data associated with axial loads on a polished rod of a pumping system wherein the rod extends down a borehole to a downhole pump and the rod is reciprocated by a surface unit to cause the downhole pump to lift fluid up through the borehole, the method comprising the steps of:

• securing a lead transducer to said polished rod to apply a transverse compressive force on said rod by said transducer at a single point along the length of said rod to measure change in the axial lead on said rod and wherein said lead transducer produces a lead output signal corresponding to change in compressive force on said rod,
• securing a position related data transducer to said polished rod to measure position of said rod and wherein said position related data transducer produces an output signal related to the position of said polished rod,
• digitizing said load output signal to produce a set of digitized change in compressive force data and digitizing said output signal to produce a set of digitized rod position related data,
• storing said change in compressive force data and said rod position related data,
• processing said change in compressive force data in conjunction with said rod position related data to produce a set of data representing changes in the axial load on said polished rod as a function of rod position, and
• displaying said set of data representing changes in the axial load on said polished rod as a waveform as a function of rod position on a screen.

A method for acquiring and displaying data associated with axial loads on a downhole pump of a pumping system wherein a polished rod is at the surface end of a rod string that extends down a borehole to the downhole pump and the rod string is reciprocated by a surface unit to cause the downhole pump to lift fluid up through the borehole, the method comprising the steps of:

• securing a load transducer to said polished rod to apply a transverse compressive force to said rod by said transducer at a single point along the length of said rod to measure change in the axial load on said rod and wherein said load transducer produces a load output signal corresponding to change in the compressive force on said rod,
• securing a position related data transducer to said polished rod to measure position of said polished rod and wherein said position related data transducer produces an output signal related to the position of said polished rod and therefore the position of said downhole pump,
• digitizing said load output signal to produce a set of digitized change in compressive force data and digitizing said output signal to produce a set of digitized rod position related data,
• storing said rod change in compressive force data and said rod position related data,
• processing said change in compressive force data in conjunction with said rod position related data and physical information describing said rod string to produce a set of data representing changes in axial load on said downhole pump as a function of pump position, and
• displaying said set of data representing changes in axial load on said downhole pump as a waveform as a function of pump position on a screen.

A method for acquiring and displaying data associated with axial loads on a downhole pump of a pumping system wherein a polished rod is at the surface end of a rod string that extends down a borehole to the downhole pump and the rod string is reciprocated by a surface unit to cause the downhole pump to lift fluid up through the borehole, the method comprising the steps of:

• securing a load transducer to said polished rod to apply a transverse compressive force on said rod by said load transducer at a single point along the length of said rod to measure change in compressive force on said rod wherein the change in compressive force is a function of the axial load on said rod and wherein said load transducer produces a load output signal corresponding to the change in compressive force on said rod,
• securing a position related data transducer to said polished rod to measure position of said polished rod and wherein said position related data transducer produces an output signal related to the position of said polished rod and therefore the position of said downhole pump,
• digitizing said load output signal to produce a set of digitized rod change in compressive force data and digitizing said output signal to produce a set of digitized rod position related data,
• storing said rod change in compressive force data and said rod position related data,
• processing said rod change in compressive force data in conjunction with said rod position related data and physical information describing said rod string to produce a set of data representing changes in the axial load on said downhole pump as a function of time, and
• displaying said set of data representing changes in load on said downhole pump as a waveform as a function of time on a screen.

A method for acquiring and displaying data associated with absolute axial loads on a downhole pump of a pumping system wherein a polished rod is at the surface end of a rod string that extends down a borehole to the downhole pump and the rod string is reciprocated by a surface unit to cause the downhole pump to lift fluid up through the borehole, the method comprising the steps of:

• securing a load transducer to said polished rod to apply a transverse compressive force on said rod by said load transducer at a single point along the length of said rod to measure change in the axial load on said rod and wherein said load transducer produces a load output signal corresponding to change in the compressive force on said rod,
• securing a position related data transducer to said polished rod to measure position of said polished rod and wherein said position related data transducer produces an output signal related to the position of said polished rod and therefore the position of said downhole pump,
• digitizing said load output signal to produce a set of digitized rod change in compressive force data and digitizing said output signal to produce a set of digitized rod position related data,
• storing said rod change in compressive force data and said rod position related data,
• processing said rod change in compressive force data in conjunction with said rod position related data and physical information describing said rod string to produce a set of data representing absolute load on said downhole pump as a function of pump position, and
• displaying said set of data representing absolute load on said downhole pump as a waveform as a function of pump position on a screen.

A method for acquiring and displaying data associated with absolute axial loads on a polished rod of a pumping system wherein the polished rod is at the surface end of a rod string that extends down a borehole to a downhole pump and the rod string is reciprocated by a surface unit to cause the downhole pump to lift fluid up through the borehole, the method comprising the steps of:

• securing a load transducer to said polished rod to apply a transverse compressive force on said rod by said load transducer at a single point along the length of said rod to measure change in compressive force on said rod wherein the change in compressive force is a function of the axial load on said rod and wherein said load transducer produces a load output signal corresponding to the change in compressive force on said rod,
• securing a position related data transducer to said polished rod to measure position of said polished rod and wherein said position related data transducer produces an output signal related to the position of said polished rod and therefore the position of said downhole pump,
• digitizing said load output signal to produce a set of digitized rod change in compressive force data and digitizing said output signal to produce a set of digitized rod position related data,
• storing said rod change in compressive force data and said rod position related data,
• processing said rod change in compressive force data in conjunction with said rod position related data to produce a set of data representing absolute loads on said polished rod as a function of rod position, and
• displaying said set of data representing absolute loads on said polished rod as a waveform which is a function of said polished rod position on a screen.

A method for analyzing the performance of an oil well pumping system having a reciprocating pumping unit, a polished rod at the upper end of a rod string and a downhole pump connected to the lower end of the rod string, the method comprising the steps of:

• clamping a load transducer to opposite longitudinal sides of said polished rod to apply a transverse compressive force on said polished rod by said load transducer at a single point along the length of said rod for sensing changes in diameter of said polished rod and generating a load signal corresponding to changes in said compressive force on said polished rod,
• digitizing said load signal to produce a first digital data set,
• measuring the acceleration of said polished rod by an accelerometer and generating an acceleration signal corresponding to the acceleration of said polished rod,
• digitizing said acceleration signal to produce a second digital data set,
• storing said first and second digital data sets, and
• processing said first and second digital data sets in conjunction with physical data for said rod string to produce a downhole pump card representing the load on said downhole pump.