GB890144A - Subsurface apparatus for automatically filling conduit strings - Google Patents

Abstract

890,144. Drilling wells. BAKER OIL TOOLS Inc. May 15, 1959, No. 16734/59. Class 85. Relates to apparatus, incorporated in a casing or drill pipe string, which permits the level of well fluid entering the string to be controlled as the string is run into the well. As shown, the apparatus A is incorporated in a casing pipe string B, C and consists of valve means held in the fluted interior of the tube 10 by a cement plug 14, the means comprising a valve seat 18, a flap 19 spring-urged upwardly about a pivot 20 to close the seat 18 against back pressure when a tube 29 is removed from its path, a differential area annular piston 28 secured to the tube 29 by shear pins 30, and a spring-loaded valve head 36 which seats on the bottom of the piston 28. When the casing string is being run into the well; the hydrostatic head outside the string acts on the lower annular surface area of the piston 28 and raises the piston away from the valve head 36 to allow well fluid to pass through the piston and tube 29 into the upper part B of the string. The upper annular area of the piston 28 is greater than the lower so that the well fluid above the piston moves the piston down to close on the valve 36 before its level approaches the hydrostatic head outside the casing. When fluid is pumped into the well, the pump pressure forces the valve head 36 down away from its seat. The tube 29 protects the valve 19 from attrition by well fluid and remains within the valve seat 18 until it is desired to make the valve 19 operative against back pressure, e.g. prior to the cementing of the casings B, C in the well bore. A heavy ball 60 is then dropped down the well to rest on a valve seat 61 in the tube 29. The pressure of the conditioning fluid shears the screws 30 and forces the tube 29 into the piston 28 until it fully depresses the valve head 36 and brings ports 62 into communication with the lower part C of the casing. When pumping of the cement slurry stops, the valve 19 is closed by its spring on to the seat 18 and prevents the slurry from flowing back into the casing string.