user: ### NOW ANSWER:
Question: what is the surface when the opponents are Louise Field Nathalie Herreman?
Columns: ['Outcome', 'Date', 'Tournament', 'Surface', 'Partner', 'Opponents', 'Score']
Types: ['text', 'text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['Winner', '25 September 1988', 'Paris , France', 'Clay', 'Emmanuelle Derly', 'Louise Field Nathalie Herreman', '6–0, 6–2']
SQL:

assistant: SELECT "Surface" FROM "Table" WHERE "Opponents" = 'Louise Field Nathalie Herreman';