Method of using a polished rod transducer
US5464058A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 17, 1995 |
| Grant date | Nov 7, 1995 |
| Priority date | — |
| Expiry date | Mar 17, 2015 |
Classification
- Technology area (CPC F)Mechanical Engineering; Lighting; Heating
- CPC primaryF04B2201/121
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
In a pumping well, oil is normally lifted to the surface by a rod which extends from the surface to a downhole pump. A transducer is attached to the rod at the surface to sense the deformation, i.e., the change in diameter or circumference of the rod to determine change in rod loading. The transducer includes strain gauges which produce output signals proportional to the change in the diameter or circumference of the rod which occurs due to changes in load on the rod. The transducer may also include an accelerometer. The change in load on the polished rod over a pump cycle is used in conjunction with data produced by the accelerometer to calculate a downhole card. The downhole card showing change in pump load is adjusted to reflect absolute rod load by determining an appropriate offset. Various ways to determine the offset are available. Since the pump plunger load is zero on the downstroke when the traveling valve is open, the value necessary to correct the calculated minimum pump value to a zero load condition may be used as the offset. The offset can also be estimated by either a calculation of the rod weight, a predetermined rod weight measurement or an estimated load value by …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.