The most important thing is to know how accurate the gyro survey tool that is being used in a project is . ( Read more about fundamental principles of a gyroscope here )
The wrongly named Gyroscope - Reference Gyroscope vs True North Gyroscope . If we take a glance at different measuring equipment that uses gyroscope technology , different classifications such as the True North Gyroscope and the Reference Gyroscope can be seen .
The reference gyroscope lacks an accurate sensor that measures Earth ’ s angular velocity projection ; therefore , it is unable to find true north , which means it cannot find the azimuth . Before anything can be done , the collar azimuth needs to be introduced manually . It is not a gyroscope itself , but a reference or indirect measurement gyroscope ( Inclinometer ) and , of course , it is not a true gyroscope .
The inclinometer , as its name implies , is a tool that determines the inclination of a well and does not measure direction directly , but rather takes it from an external point and its data depends on the human factor , which causes the accumulation of errors as you go deeper into the well . It is important to note that the measurement of a tool is not only the inclination but is also the direction ( azimuth ). Since reference gyros lack the technology and sensors necessary to search for true north and establish azimuth , they do not have the capability to measure vertical wells / boreholes . You can find more information about the difference between a reference gyro , true north seeking gyro , and magnetic survey tool here .
Reference gyros are unable to measure vertical boreholes / wells SPT GyroMaster™ is a true north seeking gyro survey tool , that can measure even with angles of +/ - 90 º. Its operation and accuracy have been proven in extreme conditions . In exploration wells that are in close proximity to each other or in complex reservoirs where precision is an essential requirement , the GyroMaster™ has been the key to the success of the project .
Risks of using Reference Gyro Survey
Figure 3 . Accuracy of the GyroMaster™ , comparing with other tools in the market
Tools in Mining Exploration The use of reference gyro survey tools in extremely important mining projects carries serious risks because their operation depends on human input . If the tool is supplied with the wrong starting data , the geology department risks falsely believing that they have found a low mineral reserve . It is the same case with other gyro survey tools that are true north seeking gyros but are not capable of repeating the measurement data during the descent to the well and the subsequent rise . That is why we have classified them as true north gyroscopes , but with low precision .
The use of reference gyro survey tools in mining exploration is as inaccurate as the use of low precision north finders .
Low precision gyros are very similar to the reference survey tools . Many times , they even obtain the initial reference point through a magnetic compass . Furthermore , because their method of operation is a single shot , they do not have the ability to measure continuously , these tools tend to accumulate errors between each measurement interval .
Evaluation of mineral reserves depends on the measurement of the trajectory Stockholm Precision Tools ( SPT ) is proud to have specialized in the development and manufacturing of highprecision gyro technology for more than 20 years such as the GyroMaster™ for the mining sector ; the GyroTracer™ , for oil and gas ; and , most recently , the Core Retriever™ , which is capable of simultaneously taking measurements and recovering cores .
The precision data of Stockholm Precision tools in inclination is 0.05 º, unlike the value offered by other manufacturers whose equipment works with a calibration that allows an error of 0.3 º, which results in the constant inaccuracy of the spatial position of the well . If we add the real deviation to this , the magnitude of the error can be 6 to 10 meters , depending on the depth and inclination of the well : the greater the inclination , the greater the projection , and therefore , the geology department will obtain incorrect data .
The main driver for writing this article is to highlight the importance of using the correct gyro technology together with a rigorous quality control process during the operation to avoid the many errors we have seen in the industry for calculating reserves that have arisen as a result of using low-quality tools with no quality control process .
Let us take , for example , an ore body which is 5 meters wide with a dip of about 45 º and a depth of 1000 meters . If we use a tool whose specifications contemplate a margin of error of 0.3 º in the inclination and several degrees in the azimuth , the possibilities of erroneous calculations on the dimensions of the mining body will be high . Therefore , the probability of underreporting the presence of minerals will
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