When performing a borehole survey for an oil and gas, mining, underground utilities, or construction project, it’s important to gather information about the magnetic field and gravitational force of the rock formation being drilled. In order to gather accurate results, though, it’s important to use the right equipment.
An accelerometer will work to gather information about the gravitational pull of any rock formation, but a magnetometer will only work on rock formations that do not have a high amount of magnetism. Instead, to gather information about the magnetic field of the rock, a gyroscopic tool must be used instead. This type of tool uses inertial navigation to determine the magnetic movement of a borehole path.
Bore Path Services offers the Gyro Shot® to measure this characteristic. If you perform borehole surveys and have encountered magnetic rock formations, stop using the differential method of optically measuring the curvature of magnetic fields. Instead, trust the latest in gyroscopic technology and purchase or rent from Bore Path Services today.
Ironstone is a magnetic rock and is sedimentary, meaning that it’s formed from an accumulation of sediment (like stones and sand). It’s gray, but usually appears brown at the surface because of oxidation. Ironstone occurs in different forms. It can occur as siderite nodules; weathered saprolite, like laterite; and ooidal ironstone.
When ironstone is present in a rock formation that is being surveyed, the use of a gyroscopic tool like the Gyro Shot® is required for an accurate reading of the magnetic field. Knowing the makeup and characteristics of rock formations and project sites helps develop efficient plans for the project.
Pyrrhotite is a mineral that also has magnetic properties and, in high amounts, will also affect the readout of a magnetometer. It is referred to as magnetic pyrite because of its similar color to pyrite. As the iron content of pyrrhotite increases, though, the level of magnetism decreases.
It is important to identify pyrrhotite because it has been linked to foundational issues in areas of Quebec and Connecticut. Because local quarries in these areas used pyrrhotite in their concrete mixtures, over time the iron sulfide in the mineral reacted with oxygen and water and caused swelling and cracking in concrete basements. In areas where large amounts of pyrrhotite exists, a Gyro Shot® can be used to measure the magnetic field and make adjustments to building plans as necessary.
One of the most common iron oxide minerals, magnetite is the most magnetic mineral found in nature and is attracted to even a common magnet. Magnetite can be found on some beaches and in river sands. These are often referred to as “black sand” because of its dark color. Crystals of magnetite are common in many types of rock. It actually helps preserve the orientation of Earth’s magnetic field because it naturally orients itself in the direction and polarity of Earth’s magnetic field.
Since this mineral is so heavily magnetized, if there is a lot of it in a rock formation being drilled for a borehole survey, the Gyro Shot® is a great tool to use to measure the magnetic field instead of a magnetometer.
For gyroscopic instruments, magnetometers, accelerometers, and more, contact Bore Path Services. We offer borehole surveying tools that are reliable and affordable. Find out more today.