Below is the list of tables from the database along with their columns and datatype. Need to generate an accurate SQL query for the question.
Only use the columns present in the respective table. Only use the columns which are required to generate the SQL query. Only use table joins if required and not otherwise.

### Tables ###
TABLE: CREATE TABLE table_name_7 ( rank INTEGER, industry VARCHAR, revenue_in_usd VARCHAR )

### Question ###
What is the rank of the petroleum company who has a revenue of $481.7 billion?

### Accurate SQL ###

SELECT MIN(rank) FROM table_name_7 WHERE industry = "petroleum" AND revenue_in_usd = "$481.7 billion"