43 CFR § 3173.9 - Required recordkeeping for inventory and seal records.
(a) The operator must perform an end-of-month inventory (gauged manually or automatically) that records: TOV in storage (measured to the nearest 1/2 inch) subtracting free water, the volume not corrected for temperature/S&W, and the volume as reported to ONRR on the OGOR;
(1) The end-of-month inventory must be completed within ± 3 days of the last day of the calendar month; or
(2) The end of month inventory must be a calculated “end of month” inventory based on daily production that takes place between two measured inventories that are not more than 31, nor fewer than 20, days apart. The calculated monthly inventory is determined based on the following equation:
For example: If the first inventory measurement performed on January 12 is 125 bbl, the second inventory measurement performed on February 10 is 150 bbl, the gross sales volume between the first and second inventory is 198 bbl, and February is the calendar month for which the report is due. For purposes of this example, we assume February had 28 days and that the well was non-producing for two of those days.
(2) The date of installation or removal of each seal;
(3) For valves, the position (open or closed) in which it was sealed; and
(4) The reason the seal was removed.