GRI is a file extension that is used by a specialized application called Petrosys. It is a program used in industry and engineering for oil exploration and production. This is a Petrosys Pty tool. Ltd. allowing for the optimal integration of data from various sources.

GRI are files used by the program to store information related to grid sampling. This solution allows you to visualize 2D and 3D maps using also a tool specific to GIS (Geographic Information System).