Boring or penetrating the earth – Boring with explosion in inaccessible hole – With bore condition firing control – or compensating means
Patent
1988-12-16
1990-05-15
Novosad, Stephen J.
Boring or penetrating the earth
Boring with explosion in inaccessible hole
With bore condition firing control, or compensating means
166 55, 175 452, 175 456, E21B 43116
Patent
active
049249525
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a detonating head which is retrievable from the well before or after it has been mechanically actuated to fire one or more perforating heads
Known detonating heads cannot be retrieved from the well in case of malfunction, to allow shot detection or for safety reasons if firing is to be deferred. It is an aim of the present invention to provide a detonating head which is retrievable and which allows the incorporation of various safety features.
According to the present invention there is provided a detonating head for detonating one or more perforating guns positioned in an oil, gas or water well, comprising a firing member reciprocable therein and arranged to be driven to detonate a detonating assembly, characterized in that the head further comprises restraining means for restraining the firing member against a driving force until the restraining means are disengaged mechanically.
According to a preferred aspect of the present invention there is provided a detonating head assembly for detonating one or more perforating guns positioned in an oil, gas or water well, the assembly comprising a retrievable detonating head, a landing sleeve and a stinger connectable thereto for communicating the explosion initiated by the detonating head to the perforating gun, said retrievable detonating head comprising a plunger assembly slidably receivable within said sleeve and including a plunger releasably retaining at its lower end a firing member drivable to detonate a detonating assembly, and latching means arranged to cooperate with engagement means at the upper end of said sleeve and with formations on the plunger such that in a first, insertion position of the plunger relative to said plunger assembly the detonating head may be inserted into said sleeve, until the latching mechanism engages the engagement means thereon; subsequent depression or withdrawal of the plunger relative to said detonating head and landing sleeve to, respectively, a second, lower firing position or to a third, upper firing position, releases said firing member permitting it to be driven to activate the detonating assembly, while positioning the latching mechanism to retain the detonating head within the sleeve against the detonation; and relative movement of the plunger to a fourth, retrievable position releases the latching mechanism to allow the detonating head to be withdrawn from the landing sleeve and be brought to the surface for inspection.
The latching mechanism is preferably constituted by longitudinally-extending dogs each having a radially outer abutment which in the firing positions is caused to project into a recess in the landing sleeve by engagement with respective lands on the plunger. Alternating with the lands are grooves in which an inner projection of the or each dog is respectively received when the plunger is in the first, insertion and fourth, retrieval positions.
Preferably the detonating head also comprises a shear pin which must be sheared when the plunger head is struck to move it to the second position or pulled to move it to the third position. The limits to the depression or withdrawal movements are preferably set by the engagement of a release shear pin mounted on the plunger housing with the respective ends of an axial slot in the plunger, the shear pin having to be sheared by movement of the plunger to the fourth, retrieval position.
The firing member of the detonator may be arranged to be driven by mechanical force applied, for example, to the plunger head. Alternatively, the firing member may comprise a piston reciprocable within a piston housing of said detonating head the arrangement being such that said piston is drivable within said piston housing by well hydrostatic pressure.
The detonating head assembly according to the present invention affords the following advantages.
(1) The detonating head can be run into the firing position by means of a slick-line or wire-line run after the perforating guns have been positioned at the correct depth, allowing the operators to run the gu
REFERENCES:
patent: 3800705 (1974-04-01), Tamplen
patent: 4544034 (1985-10-01), George
patent: 4610312 (1986-09-01), Nelson et al.
patent: 4650010 (1987-03-01), George et al.
Novosad Stephen J.
Reynolds Florence U.
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