equipment and where feasible through the use of conventional rig equipment that is in many cases already available on site with its own dedicated wellhead pressure control choke the method may be operated separately from the drilling fluid circulation system and does not rely upon or utilize the rig choke the method further minimizes the need to increase personnel requirements which is particularly attractive in off shore drilling environments the process provides for a simple determination of set points 1 and 2 which correspond to circulating and non circulating conditions and allows for a simple mechanical pneumatic hydraulic or electromechanical automation of the control system in addition through adjustments made to the circulation rate and or the wellhead pressure applied to the annulus the method is able to accommodate the effects of surging and swabbing as the drill string is advanced or retracted from the well the simple control strategy also promotes acceptance by rig operators by eliminating the u201c black box u201d effect that complex microprocessor and computer systems often invoke the addition of a bias control enhances rig safety when a sudden influx or kick is encountered the above described method further permits an operator to easily and quickly determine the effects of increasing or decreasing mud weight upon the well under current systems where an operator wants to increase or adjust the.