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Why I need a CRS Registry – Part 1

Originally published on LinkedIn:

Oil drilling rig with drill pipe, and CRS Registry with equipment records and location coordinates

A CRS registry can keep track of all of the CRS components and associated transformations, greatly decreasing errors in positioning, and potentially saving millions of dollars.

With the ubiquity of cellular phones and GPS, one might think that locating things on or under the surface of the earth is no longer a problem. Unfortunately this is not quite the case. Modern exploration for oil and gas involves the drilling of holes in the earth which may extend to a depth of several kilometers, may take a path which is not a straight line, and may deviate significantly from vertical.

In such circumstances, the position of the drill bit can only be determined by referencing it to the drilling rig, the location of which is known relative to the earth. The data collected in the drilled hole, referring to rock properties and the presence of oil or gas, may then in turn be referenced relative to previous measurements (e.g. seismic) or models of the subsurface geology, which may have used completely different reference systems. Additionally, if a drill core is withdrawn from the drill hole, the rock material will be known relative to the arc length along the hole, which must then be related to the drilling rig and to previous measurements or models of the subsurface geology.

A typical drilling operation thus involves the use of multiple coordinate reference systems, including vertical ones, which must be related to one another using multiple coordinate transformations. While some of these coordinate reference systems and transformations are well known and have names, others are unique to a particular drilling project. In all cases, it is essential that the coordinate transformations and their associated parameters be recorded and be easily and reliably accessed by various participants in the exploration process. Errors in the process can easily lead to misalignment of the information sources and significant misunderstandings of the subsurface geology.

Keeping track of which coordinate system was referenced for the location of each segment in the drilling sequence – the rig, the hole, the bit, and the core – is where the value of a CRS registry is realized. In the CRS registry, each segment has a record which is associated with the relevant coordinate reference system. All related records in the sequence are associated with each other, and with the transformations that are needed to convert the coordinates between each reference system. The record for any one segment in the drilling sequence can be easily traced from any of the other segments, and everything necessary for the precise location of any part is linked together.