hi,

see it depends on the organization and the way of work experiences or knowledge requires, however petroleum engineering and chemical engineering both are different, where petroleum engineering is most in focused on petroleum or  production of hydrocarbons, which can be  crude oil or natural gas Exploration and production manufacturing process,  which is closely related with the oil and gas industry.  however chemical engineering has many concepts related with mechanical engineering, thermal engineering, nuclear reactor, and power plants. see if you donot get any relevant job after passing btech then you may go for mtech or mba course related with petroleum Industry , which has more scope for career growth.