prospecting and development of oil and gas fields, oil operations, including prospecting, drilling, extraction, preparation, transportation, marketing and sale; refining of oil and gas, oil products manufacturing; seismic and other geophysical researches and studies; trade in oil products on domestic and foreign markets; petrochemistry products manufacturing; design, construction and exploitation of industrial explosible and inflammable and mining practices, electrical stations, electric power lines and substations, water development works, oil and mains, lifting equipment, and building and operation of boilers, vessels, mains operating under pressure