Flowback Sales

Would someone please explain “flowback sales” on a horozontal well.

As frac water flows back out of wellbore, oil comes with it. Oil is separated and sold. Usually well test for initial potential is after all or most frac water has been recovered. On completion report, there is a box for the oil volumes produced prior to test date. Some companies will test immediately after frac while still recovering water so oil production looks low and water is huge. One way to keep results more confidential.