Simplify the following text for a Grade 15 native English-speaking person.
Original: Before of the depression 's development , several oil and gas companies removed unneeded workers from offshore oil platforms in the northern Gulf of Mexico ; the Shell Oil Company evacuated about 700 employees , while Noble Energy removed its workforce of about 300 people from two oil rigs .
Simplified: Prior to its development , several oil and gas companies removed unneeded workers from offshore oil platforms in the northern Gulf of Mexico ; Shell Oil Company evacuated about 700 employees , while Noble Energy removed its workforce of about 300 people from two oil rigs .