315576
Formerly known as the Semitropic Gas Field , it was discovered by the Standard Oil Company of California in 1935 , and first understood to be primarily a natural gas reservoir ; however , in 1956 a much deeper oil-bearing zone was discovered .
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Given options, please tell me the categories of all the listed entity words.Output format is "type1: word1; type2: word2". 
Option: location, person, organization 
Text: {0} 
 Entities:  
Answer:
 None