Answer: It is chemical energy, which is a type of potential energy.
Step-by-step explanation: Natural gas consists of mixture of hydrocarbons such as methane, butane and others which are chemical substances, thus they contain chemical energy stored in the bonds of the molecules.
Potential energy is any form of energy that has stored potential that can be used later. Examples include nuclear energy, chemical energy, etc.
Thus the type of energy present in natural gas is chemical energy, which is a type of potential energy.