Method and apparatus for detecting plunger arrival
View Patent ↗The disclosed device provides a high-accuracy plunger arrival detection system comprising a low-power magnetometer with high sensitivity and which is capable of sampling low or high intensity magnetic fields. The device processes gathered data from sensors, stores at least some processed data in memory, executes a trending algorithm which compares the magnetic field of the plunger to the ambient magnetic field or a predetermined set of initialization values, and generates an output which is relayed to a well controller. An output signal may be via hard wire, RF, wireless or other known means. In addition, the implementation of two sensing devices mounted in series and in spaced relation to each other, can provide for an actual plunger average velocity. An actual plunger average velocity, as opposed to approximate average velocity, can be used to better optimize well control and improve safety of the overall well production system.
1. An apparatus utilizing a magnetic inductive sensor for detecting a plunger arrival at a wellhead, said apparatus comprising:
a power supply;
a magnetometer system having at least a first axis magnetic field sensor and a second axis magnetic field sensor, wherein axes of said magnetic field sensors are transverse;
a microprocessor system adapted to manage and control the magnetometer system, the microprocessor system further comprising electronic memory;
the magnetometer system coupled to the microprocessor for measuring a magnetic field value of a first axis of using said first axis magnetic field sensor and a magnetic field value of a second axis using said second axis magnetic field sensor;
the microprocessor gathering magnetic field data from said magnetometer system and configured to:
identify, from a measurement of said magnetometer system, a first magnetic field change greater than a predetermined delta of one of said first axis and said second axis relative to a corresponding one of first and second baseline magnetic field values for said first axis and said second axis;
identify a second change in a magnetic field value of one of said first axis and said second axis to a previous magnetic field value of a previous magnetic field value of said axis; and
upon identifying said first change and said second change, generate an output to an electronic wellhead controller to indicate a plunger arrival; and
wherein one or both of the magnetometer system and the microprocessor are mountably located at an exterior position of a lubricator.
2. The apparatus of claim 1 , wherein said microprocessor is further configured to:
generate said first and second baseline magnetic field values for said first axis and said second axis.
3. The apparatus of claim 2 , wherein said microprocessor generates said first and second baseline magnetic field values based on a running average of a predetermined number of previous magnetic field measurements for said first axis and said second axis.
4. The apparatus of claim 1 , wherein said processor is configured to identify said first change in said magnetic field of one of said first axis and said second and identify said second change in a magnetic field of the other of said first axis and said second axis in said immediately subsequent measurement.
5. The apparatus of claim 1 , wherein said magnetometer system further includes a third axis magnetic field sensor, wherein an axis of said third axis magnetic field sensor is transvers to axes of said first magnetic field sensor and said second magnetic field sensor.
6. A method for utilizing a multi-axis magnetic inductive sensor for detecting a plunger arrival at a wellhead, comprising:
operating a magnetometer system to measure magnetic field values of first and second transverse axes, wherein said magnetometer system is mounted to a wellhead;
operating a processor to generate at least a first axis baseline value and a second axis baseline value using said magnetic field values from said magnetometer system;
operating said magnetometer systems to measure subsequent magnetic field values of said first and second transverse axes after generating said baseline values;
operating said processor to:
compare said subsequent magnetic field values to said baseline values;
identifying a first change in a magnetic field value for one of said first and second transverse axes, said first change being greater than a predetermined value, relative to a corresponding one of said first axis baseline value and said second axis baseline value;
identifying, a second change in a magnetic field value of one of said first axis and said second axis relative to a previous magnetic field value for said axis; and
upon identifying said first change and said second change, generating an output to an electronic wellhead controller to indicate a plunger arrival.
7. The method of claim 6 , wherein said microprocessor operates to generate generates said first axis baseline value and said second axis baseline value based on a running average of a predetermined number of previous magnetic field measurements for said first and second transverse axes.
8. The method of claim 6 , wherein said processor operate to identify said first change of one of said first and second transverse axes and identify said second change in the other of said first and second transverse axes.
9. The method of claim 1 , wherein said manometer system operates to measure magnetic field values along a third axis transverse to said first and second transverse axes.