| 摘要 |
PCT No. PCT/GB87/00430 Sec. 371 Date Dec. 16, 1988 Sec. 102(e) Date Dec. 16, 1988 PCT Filed Jun. 19, 1987 PCT Pub. No. WO87/07925 PCT Pub. Date Dec. 30, 1987.A detonating head assembly (30) for detonating perforating guns in an oil, gas or water well, comprises a retrievable detonating head (34), a landing sleeve (50) and a stinger (42). The detonating head (34) comprises a plunger assembly (36) slidably receivable within the sleeve (50) and including a plunger (64) releasable retaining at its lower end a piston (94) reciprocable within a housing (92), the piston (94) when released being actuable by hydrostatic pressure to detonate a detonating assembly (40), and latching dogs (58) co-operating with a recess (56) and with formations on the plunger (64) such that in a first, insertion position the detonating head (34) may be inserted into the sleeve (50), until the dogs (58) engage in the recess. Subsequent depression or withdrawal of the plunger (64) relative to, respectively, lower firing position or an upper firing position, releases the piston (94) permitting it to advance under the action of hydraulic pressure to activate the detonating assembly (40), while positioning the plunger (64) to ensure the dogs (56) remain engaged during detonation. Withdrawal of the plunger (64) to an uppermost position releases the dogs (58) and allows the detonating head (34) to be withdrawn from the landing sleeve (50) and be brought to the surface.
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