The migration of gas from oil and gas fields to the surface is a problem that can greatly affect areas of urban development. Oilfields have demonstrated a long history of gas migration problems. Experience has shown that the migration of gas to the surface can create a serious potential risk of explosion, fires, noxious odors, and potential emissions of carcinogenic chemicals, such as BTEX. These risks must be seriously examined for any oil and/or gas operations in urban areas. Oilfield operations, however, can be conducted safely if proper precautions are taken.