CREATE TABLE table_15217 ("Field" TEXT, "Geological Trend" TEXT, "Reserves" TEXT, "Discovery" TEXT, "Operator ( s ) " TEXT)

Which Geological Trend has an Operator(s) of woc?
SELECT "Geological Trend" FROM table_15217 WHERE "Operator(s)" = 'woc'
SELECT "Geological Trend" FROM "table_15217" WHERE "Operator(s)" = 'woc'