GB1338295A - Method of and system for maintaining a drilling fluid near a reference level in a well shilst trippiing - Google Patents

Abstract

1338295 Boring earth &c L W LEONARD 10 Aug 1971 [28 Aug 1970] 37586/71 Heading E1F While tripping a pipe string out of, or into, a well containing drilling fluid, the loss of drill fluid into the formation, or the entry of formation fluid into the well, is detected by comparing the volume of the pipe string leaving or entering, the well with the volume of drilling fluid added to, or withdrawn from, the well to maintain fluid in the well at a reference level. During a withdrawal trip the number of pipe stands 44 passing a detector 50 are shown on a counter 52, and the volume of the stands, or the quantity of fluid theoretically required to maintain the reference level 60<SP>1</SP>, is shown on a counter 56. A signal from the counter 56 cause a valve controller 55 to actuate a valve 30 to direct fluid from a pump 18 through a fill line 25 and via a meter 32 to the well. When the fluid reaches the reference level a signal from a detector 60 cause the valve controller to stop supply to the well. Signals from the meter and the counter 56 are fed to a comparator 64 which operates warning light 70, 72, 74 for normal, fluid loss and fluid entry conditions. A sudden flow into the well is indicated by a warning light 71 actuated by a detector 61. In a modification (Fig. 2, not shown) suitable for both withdrawal and insertion trips, the pump circulates the fluid between suction and discharge lines (24, 23) connected to the valve, a further valve (80) is connected to the valve, the valve controller and fill and return lines (25, 24), and the detectors 60, 61 are respectively below and above the return line. The modification can also be used to maintain constant level in the well.