CREATE TABLE table_15219 ("Field" TEXT, "Geological Trend" TEXT, "Reserves" TEXT, "Discovery" TEXT, "Operator ( s ) " TEXT)

Which Field has a Discovery of na, and an Operator(s) of woc, and a Geological Trend of western
SELECT "Field" FROM table_15219 WHERE "Discovery" = 'na' AND "Operator(s)" = 'woc' AND "Geological Trend" = 'western'
SELECT "Field" FROM "table_15219" WHERE "Discovery" = 'na' AND "Geological Trend" = 'western' AND "Operator(s)" = 'woc'