GB1394457A - Method and apparatus for the completion of well bores - Google Patents

Abstract

1394457 Wells R R VANN 5 Dec 1972 55975/72 Heading E1F [Also in Division F3] A method in which a lower hydrocarbon zone of a well is completed after an upper hydrocarbon zone of the well has been completed, comprises suspending a packer 20, Fig 1, and a casing perforator 23 on the end of a tubing string 13, positioning the packer and perforator down hole by using the tubing string, forming a fluid flow path from below the packer 20 which communicates with the interior of the tubing string, completing the upper zone, completing the lower zone by actuating the perforator, leaving the perforator downhole, and producing the lower zone through the tubing string and producing the upper zone through an annulus 15 formed between the tubing string and the upper portion of the casing 12. Communication is provided 'between the lower zone and the interior of the tubing string by means of a perforated nipple 21, and by swabbing the interior of the tubing string. The perforator 23 is preferably a casing gun having deep-penetrating shaped charges. The gun-firing mechanism, Fig 2, comprises a firing pin 51, a thin copper wafer 55, an assembly 41 having three bores (54), Fig 6 (not shown), with 22-calibre primers disposed therein, a detonator 39 and primer cord 38. Detonation is achieved by a free-calling weight 45 which shears pins 50 and causes an enlargement 49 to impact the firing pin 51. In an alternative embodiment, Fig 14 (not shown), a shaft (89) comprises two parts joined by a pin (150), and for detonation, the shaft is pulled upwardly by the tubing string against the action of a spring (93) until the pin (150) breaks, and the compressive force of the spring urges the lower part of the shaft downwardly to impact the detonator 39. In further alternative embodiments, Figs 10 and 13 (not shown), the casing gun is electrically actuated by means of a gamma ray tool (60) which is attached to a wire line (62) having a conductor therein. The lower tubing can be isolated by a plug (14'), Fig 8 (not shown), and the tubing string removed form the packer so as to enable completion of the upper zone without the danger of falling debris or inadvertent firing of the gun. Fracturing and acidizing processes may be carried out simultaneously with the firing of the gun.