A coal formation may be treated using an in situ thermal process. A mixture of hydrocarbons, H.sub.2, and/or other formation fluids may be produced from the formation. Heat may be applied to the formation to raise a temperature of a portion of the formation to a pyrolysis temperature. The formation to be treated may be chosen so that the mixture produced from the formation will have a desired amount of condensable hydrocarbons and non-condensable hydrocarbons. The formation to be treated may be chosen based on an initial vitrinite reflectance of the formation.