Local Earth Magnetic Field Measurements
We offer real time, on-site measurements of the earths magnetic field parameters. Previous experience has shown that the typical computer generated magnetic field models, which are predominantly utilized in the industry, can create unacceptable magnetic accuracy errors while drilling. Ultimately, these errors can incorrectly identify the actual bottomhole position and the real time placement of a wellbore, causing a multitude of problems in the event a relief well interception of the blowing well is required.
We provide accurate measurement of on-site magnetic field parameters for not only relief well drilling, but also for stringent anti-collision operations, critical geologic targeting and prevention of asset disputes among operators.
Our experience and ability to locate and intersect wellbores has proven the importance and critical nature of definitive and accurate wellbore positional information. When an In-Field Monitoring Program of the earths magnetic field is required, our service can provide the necessary data.
WE CAN PROVIDE:
- Complete Earth Magnetic Field Data Measured Onsite
- Magnetic Dip, Including Total, Horizontal and Vertical Components
- Magnetic Declination Verification, Correction and Calculation Capabilities
- Wellsite Geographic Coordinates Verification for Blowout and Relief Well Sites
- Independent and Unbiased Measurement of Earth Magnetic Field Components
We utilize a Zeiss MAG-02B Non-Magnetic Theodolite with an integrally mounted Single Axis Fluxgate Magnetometer. The theodolite is set atop a Non-Magnetic Tripod and a Magnetometer Readout box is attached to the magnetometer.
This Theodolite and Magnetometer Assembly have the following specifications:
+/- 500 mT
-10º to +50º C
3 Seconds of Arc
MAGNETIC FIELD RECORDING OPERATIONS SUMMARY
- A minimum of two points located in a magnetic free environment and adjacent to the drilling area are initially selected. These points are known as earth field measurement points and become permanently set for future observations which are made both prior to and during the drilling operations.
- A qualified land surveyor must "set these points in" followed by a solar observation to determine an accurate and independent azimuth between the points.
- Cross-checking of the computed geographical coordinates, including the relationship between the measurement points and the blowout site is then made. It is during this step that many errors have been found. On a particular project, a set of operator supplied geographic coordinates showed a ~50m distance discrepancy between the actual blowout and the relief well wellheads.
- The Zeiss Theodolite, with magnetometer and readout, are setup on the initial measurement point and a line of sight to the second point is established. Using the Null Mode Method, the real-time earth magnetic field is measured. From this measured data, the magnetic field components are calculated.
- Comparisons with the on-site measurements and the computer model generated values are made. Then corrections are applied to both real time and pre-blowout events to accurately identify the BHL of the subject well. This data, combined with a real-time Wellbore Surveying Quality Control Program, can significantly reduce measureable magnetic errors, both inherent and induced.
Click here to see the theodolite