US 4,380,948 AGranted

Loading of wellbores with explosives

AssigneeE. I. Du Pont de Nemours and Company

InventorsFrank A. Loving, Jr., Walter J. Simmons

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Abstract

Bags of explosive are loaded rapidly into deep wellbores by suspending a rigid positioning tube partway into the wellbore, and loading the bags into the tube, the bags being prevented from dropping through the open bottom end of the tube by a cord attached to the lowermost bag and secured at the upper end of the tube when the tube-suspending cable is in tension by a cord-securing/releasing means, e.g., a pivotable bar having a hook on one end. When the bag-laden tube is lowered to the bottom of the wellbore, or to a column of bags previously placed therein, the tension on the cable is relaxed and the cord is released, allowing the positioning tube thereafter to be raised to the surface for re-use, leaving the cord and bags in the wellbore. Freedom of the bag-supporting cord to move with respect to the positioning tube when the latter is raised to the surface is assured by threading the cord through plastic tubing mounted to the wall of the positioning tube and releasable therefrom for re-use.

Claims9

Dependent claims

A method of loading bags of explosive into a wellbore comprising:

(a) suspending in the wellbore a rigid bag-positioning tube having its open bottom end within the wellbore and its top end outside the wellbore, said top end being adapted to receive a tube-suspending cable having one of its ends attached inside said positioning tube and the other to an external tube-supporting fixture;
(b) threading a length of cord through a length of plastic tubing, one exposed end of said length of cord being provided with a loop and the other attached to a bag of explosive;
(c) introducing said bag of explosive into said positioning tube through an access port therein above the top of the wellbore, lowering said bag to the bottom of said tube, and attaching the loop on the end of said length of cord to a cord-securing/releasing means affixed to an inside surface of said positioning tube adjacent its top end, said cord-securing/releasing means acting in cooperation with said cable to secure said cord when said cable is placed under tension by the weight of the suspended tube, and to release said cord when the tension on said cable is relaxed, said tubing being releasably secured longitudinally to the inside wall of said positioning tube;
(d) dropping additional bags of explosive into said positioning tube;
(e) lowering the bag-laden tube to the bottom of the wellbore by paying out the tube-suspending cable, whereby relaxation of tension on the cable causes said cord to be released from said tube;
and
(f) applying tension to the cable and thereby raising said positioning tube to the top of the wellbore whereby the released bag-supporting cord and the bags of explosive remain in the wellbore.

4 more elements

Dependencies are inferred from the claim text.