I have field crews who work out of town. If I pay $152.00 daily for 8 hours and they work 6 or 7 days, may I still pay them $152.00 daily?

Are they hourly (I would guess) and State might matter.

Over time is subject to your local state laws. But after 40 hours in a week, you will normally be paying 50 percent extra
(time and 1/2) for over time pay.

You are paying 19 dollars per hour. So for work over 40 hours you would be paying 28.50 per hour or 228 dollars per 8 hour day. Excepts would be of course if they are salary workers but a field crew does not sound like a salary position.

Also if you have been doing this for some time, remember, they can go back for years and claim any over time not properly paid. I know of one right now going back about 5 years on unpaid over time, it will cost them 100's of thousands of dollars.