Geo-energy is a resource available widely on Earth that consist in using the first 10-100 meters bellow surface where the temperature is low and constant during the year. This 12 to 15°C is ideal for heat pumps to provide heat and cold with an excellent coefficient of performance. Despite a very high potential, this resource is not often integrated in France. One of the main reasons is the lack of knowledge of rocks capacity to deliver sufficient power on surface. More than 2 millions of scanned documents are available on the french geological survey. We propose a way to classify and analyze them in order to quantify the underground resource.