GB393637A - Improvements relating to equipment for bore-holes or wells - Google Patents

Abstract

393,637. Wells and bore-holes. SEAMARK, L. M. C., Outer Down, Chagford, Devon. Oct. 7, 1931, No. 27883. [Class 85.] An internal blowout preventer for use in boreholes or wells comprises an internal plug held fixedly against the well pressure while plain or perforated tubing is run into or withdrawn from the bore-hole &c. In Fig. 1 an elastic sleeve c of rubber &c. is compressed on a tube d between a body a and a washer e and nut e<1>; within the sleeve c is a perforated sleeve with conical ends, one or more split spring rings g surrounding the sleeve f and exerting outward pressure on the sleeve c. The well pressure may also be applied to the sleeve c through apertures d<1> in the tube d. A valve h, pressed upwardly by a spring h', is arranged in the body a and may be opened by a rod to equalize the pressures on opposite sides of the device ; alternatively, high pressure may be applied above the valve to open it. Jaws i are pivoted to the body a and have internal recesses i<7> adapted to engage a flange j<1> on a mandrel j. One or more split spring rings k tend to move the jaws to release the mandrel. The mandrel j is longer than the sections of tubing b, and has buttress threads j<2>, Fig. 6, adapted to be engaged respectively by clamps m, n. In use, the dogs are engaged with the mandrel and the device is inserted into a length of tubing b which is then passed through an external blow-out preventer p as in Specifications 358,419 and 389,513, and into a container p<1>, Fig. 9, on the well head ; the mandrel is then held by the clamp m with the sleeve c adjacent the external blow-out preventer p, a valve p<3> is opened and the tube b forced into the well by suitable gear. The upper end of the tube b is then fixed by an anchored clamp o, the clamp n is secured to the mandrel and engaged with the clamp o by pivoted bolts o<1>, the clamp m is freed and a further length of tube is passed over the mandrel ; the clamp m is again secured and the clamps n, o freed, the lengths of tubing are threaded together, and the tubes are again lowered. At a part such as the top of the last length of perforated tubing, a coupling l, Fig. 1, with an internal shoulder l<1>, may be secured to the tubing; when the dogs enter the coupling, the spring rings k expand the dogs into engagement with the shoulder i<1>, so freeing the mandrel, further operations being effected without the mandrel and the plugging device entering the well with the tubing. A fishing tool may be engaged with hooked ends i<5> on the dogs to free and raise the device when required. The tube d may be extended to provide for attachment of one or more further plugging devices whereby should one device become ineffective, gas may byepass said device to put a further device into action ;' a valve h may be provided only on the upper device. Alternatively, a valve h may be provided in each device as in Fig. 5, and further non-return valves q<3> may be provided whereby the devices may be forced into the well by pressure applied above.