Patent GB-351344-A (GB)
Title: Improvements in or relating to well surveying devices
IPC: E21B47/022
Filed: 1930-09-19
Abstract: 351,344. Borehole clinometers. JACKSON, L. MELLERSH-, 28, Southampton Buildings, London.-(Sperry-Sun Well Surveying Co. ; 1608, Walnut Street, Philadelphia, U.S.A.) Sept. 19, 1930, No. 28077. [Class 97 (ii).] Borehole clinometers of the type in which the mark of a liquid surface is indicative of the slope of the hole are characterized by means to control the commencement of operation of the device and means for draining the recording liquid from the record chamber. Means for absorbing shock and for recording the orientation of the bore-hole simultaneously with the inclination may also be provided. As shown in Fig. 1, the device comprises a casing 2 closed at the top and bottom by plugs 4, 6 respectively. Within the casing are secured four sections of pipe 8, 10, 12, 14 coupled together to form four chambers, with a plug 60 closing the top of section 8. The plug 16 connecting section 8 to section 10 has an interchangeable restricted orifice 58. The plug 20 connecting section 10 to section 12 carries a siphon 22, the longer leg of which extends to the bottom of the record chamber 12. The shorter leg of siphon 22 terminates a considerable distance from the bottom of chamber 10. A second siphon 26 is carried by the plug 24, its shorter leg opening adjacent the top of the plug, and its longer leg passing through the plug and terminating in a restricted orifice 28 discharging into chamber 14. The interval between the placing of the ink in chamber 8 and the arrival of the liquid level in chamber 10 at the bend in siphon 22 is sufficient to permit of the assembly and lowering of the device. The liquid siphons over into chamber 12 until the level in chamber 10 drops to the lower end of the shorter leg. While discharge from chamber 12 takes place when the level reaches the bend of siphon 26, the incoming flow is more rapid so that the ink reaches a level above the bend momentarily, and then chamber 12 is drained. The position of the surface of the ink at its highest level will be marked on the paper cylinder 32, preferably cross-sectioned. Equalization of pressure is ensured by holes in the upper ends of the chambers. The apparatus may be adapted to provide a number of records at different levels by increasing the number of chambers. A record may be obtained when the drill ceases to rotate by substitution of section 36, Fig. 3, for section 10. In this modification a tube 38 communicates with the bottom of chamber 8 and discharges into an opening 40 in the valve 42, the other end of which communicates with a tube 44 extending to the bottom of chamber 12. The opening 40 is normally closed by a plug 46 carried by a spindle 48 with a right-hand thread and crossing a paddle 52 submerged in the mercury 56. Clockwise rotation causes the assembly to move as a whole but when the drill is stopped the inertia of the mercury causes the spindle 48 to withdraw plug 46 and initiate the flow of ink. The apparatus may also be set into operation by valves opened by a trigger striking the bottom of the hole, by artificial increase of mud pressure or by clockwork, or by the provision of a large weight in chamber 10 so suspended that deceleration at the bottom of the bore-bole causes the weight to fall into the liquid and initiate flow through the siphon. To obtain the orientation of the hole, the chamber 62, Fig. 4, may be located between chambers 12, 14, discharging into chamber 14 through a restricted orifice. Accumulation of liquid within the chamber causes a hollow brass weight 66 to float, unclamping a compass needle 70. When the liquid falls the weight causes the inner forked end of lever 68 to clamp the needle 70 against the glass plate 80 in the position which it assumed when turning freely. The compass box 72 is supported in gimbals. The adjacent parts of the apparatus are made of non- magnetic material. Shock-absorbing means, Fig. 6, comprise a steel tube 92 threaded within the drill-pipe at the desired point and closed at its lower end by a plug 94 having a small opening 96 therethrough. Adjacent its upper end are the large holes 98, the distance between the latter and the plug 94 being greater than the length of the instrument, which is provided with rubber shockabsorbing ends 102, 104. There is a close sliding fit between the casing 100 and the tube 92. When the casing 100 passes the position of the hole 98, the flow of mud therethrough is substantially cut off and the mud below the instrument has to pass through the restricted opening 96.