Table: challenger_clients_2
Columns: client
years_of_operation
area_of_operation
country
services

Question: Where is the area of operation that had drilling during the year 1999?
SQL: SELECT "area_of_operation" FROM challenger_clients_2 WHERE "services" = 'drilling' AND "years_of_operation" = '1999'

Question: What country did the client Agiba-agip work in?
SQL: SELECT "country" FROM challenger_clients_2 WHERE "client" = 'agiba-agip'

Question: What years was soc a client?
SQL: SELECT "years_of_operation" FROM challenger_clients_2 WHERE "client" = 'soc'

Question: What years was El Mabrouk the area of operation?
SQL: SELECT "years_of_operation" FROM challenger_clients_2 WHERE "area_of_operation" = 'el mabrouk'

Question: What services were in the area of operation Wadi Borjuj?
SQL: SELECT "services" FROM challenger_clients_2 WHERE "area_of_operation" = 'wadi borjuj'