 What geologic characteristics are important to consider when developing oil and gas from shales? There have to be several overlapping conditions for an economic gas shale. The gas shale has to have organic matter to a certain percentage. Usually we think of two or three or four weight percent organic matter in the shale to make it viable. That organic matter has to be subjected to just the right temperature and right pressure for the generation of gas. If the shale is too deep, the gas is burned out. If the shale doesn't achieve depths that are at the necessary temperature, gas is not generated in the first place. The shale has to be thick enough to be economic. There are a lot of gas shales that are just thin layers and not worthwhile in terms of exploration for the industry. The preservation of a gas shale like the Marcellus in an economic Marcellus is at a depth of somewhere in the order of two kilometers and a thickness that exceeds somewhere on the order of 20 meters to be just right for production.