Patent GB-827885-A (GB)
Title: Apparatus for investigating earth formations
IPC: E21B49/10
Filed: 1957-01-23
Abstract: 827,885. Boring earth. SCHLUMBERGER WELL SURVEYING CORPORATION. Jan. 23, 1957 [Jan. 23, 1956], No. 2457/57. Class 85 A fluid sampler comprising a support to be lowered down a borehole to the level of a selected earth formation, a wall engaging shoe mounted on the support and movable to engage the formation, a sample admitting portion on the shoe, and a sample receiving conduit adapted to be connected to the formation via the sample receiving portion, has means for indicating the pressures in the system for moving the shoe and in the sample receiving conduit. The samples comprises a section 22 containing a hydraulic system for driving the actuators of the shoe 20 and a back up shoe 21, a section 23 housing a sample receiving chamber 106, and side rails 24, 25 connecting the sections and carrying the actuators and shoes. The shoes 20, 21 are extended by hydraulic fluid supplied to cylinders 39...42 and are retracted by springs 44, 45. The sample admitting portion 27 of the shoe 20 comprises an insert which is surrounded by a rubber sealing face 28. The sampler is electrically controlled by moving a switch 53, and the pressure and control current are recorded against time by a recorder 78, and indicated on meters 77, 91, 102, leads for the circuits running through a cable 26 supporting the sampler in the borehole. As the sampler is lowered in the borehole the pressure of the drilling fluid increases to increase the pressure in the cylinders and in a line 43 to operate a transducer so that the recorder gives an indication of the depth to which the sampler has been lowered. When the selected formation 17 is reached a contact 52 is engaged by the switch to open a valve 48 to apply pressure of the drilling fluid to a pressure multiplier 46 which applies pressure to the line 43. The shoes 20, 21 are moved into engagement with the wall of the borehole by the pressure in the line 43, the pressure being regulated by a valve 65 to be greater than the pressure of the adjacent drilling fluid by a set amount. After the movement of the shoes the switch is moved to a contact 100 to fire an igniter 97 to propel a bullet 95 along a bore 94 to perforate a disc 93 which normally blocks formation fluid from the sample receiving conduit 84, the pressure in the conduit actuating a transducer 80 and causing the recorder to indicate the pressure in the conduit. After the formation fluid sample has collected in the chamber 106 the switch is moved to engage the contact 121 to operate a valve 119 to bleed fluid from the line 43 to a low pressure chamber 123 to release the shoes and to direct some of the fluid into a line 117 to close a valve 105 which cuts off the sample from the formation. If the shoes do not retract the switch is moved to the contact 127 to fire an igniter 130 to vent the front to the rear face of the shoe 20 to break the seal. If the pressure in the line 43 has not dropped the switch is engaged with a contact 132 to open valve 125 to bleed the line into the chamber 123. When the shoes are free the sampler is hoisted to the surface and the sample removed through valve 112.