(a) Drilling fluid control. Before starting out of the hole with drill pipe, the drilling fluid shall be circulated with the drill pipe hung just off bottom until the drilling fluid is properly conditioned. Proper conditioning requires circulation of the drilling fluid to the extent that the total annulus volume is displaced and until gas is removed. When coming out of the hole with drill pipe or tubing, the annulus shall be filled with drilling fluid before the drilling fluid level drops below a calculated depth of 100 feet below the derrick floor. A mechanical device that indicates the amount of drilling fluid required to keep the hole full shall be watched. If there is any indication of “swabbing” or influx of formation fluids, the inside blowout preventer shall be installed on the drill pipe, the drill pipe shall be run to bottom, and the drilling fluid properly conditioned. The drilling fluid shall not be circulated and conditioned except on or near bottom, unless well conditions prevent running the pipe to bottom. The fluid in the hole shall be circulated or reverse circulated prior to pulling drill-stem test tools from the hole.

(b) Drilling fluid testing equipment. Drilling fluid testing equipment for measuring viscosity, water loss, weight, and thixotropic properties shall be maintained on the drillsite at all times. Tests of the drilling fluid consistent with good operating practice shall be performed at the beginning of each eight-hour tour while drilling, with additional tests as conditions warrant. Results of tests shall be recorded on the driller's log. The following or comparable equipment for monitoring the drilling fluid system must be installed with the indicators at the driller's station and used throughout the period of drilling after setting and cementing the first surface casing.

(c) Inspection of the complete drilling fluid system shall be made by a Division inspector. Approval of the system is required prior to drilling out the shoe of the first surface casing.