US 4,750,570 AGranted

Formation sampling bullet and cables therefor

AssigneeBarrett Machine Works

InventorBracell P. Barrett

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Abstract

Sampling bullets of the type which are fired into rock formation surrounding a wellbore. The core sampling bullet includes an internal core barrel which is defined in part by a core receiving sleeve releasably secured within the bullet structure. Following bullet retrieval, the bullet is disassembled thereby permitting rearward removal of the core sleeve with core entrapped therein. Following extraction from the bullet, the core sleeve protects the core during handling and testing. The removed core sleeve is further closed by end cap members to further secure the core against contamination and against further loss of gas in core sample prior to testing. The bullet construction also provides for efficiency of hydraulic venting during firing and provides efficiently for bullet with core removal by means of one or more cables. Core orientation is also achieved.

Claims16

Dependent claims

In a formation sampling bullet adapted to be fired at high speed by an explosive charge from a support apparatus into an earth formation adjacent to a well borehole to penetrate the formation with a nose portion of the bullet to obtain and hold a formation core sample in a longitudinal bore extending rearwardly from said nose member portion of said bullet, the bullet comprising:

(a) an initial contact nose portion at a forward end of an elongated core barrel, said nose portion terminating at a circular opening of specified diameter at said nose portion, said nose portion including an exposed cutting means around said opening to cut a sample core entering into an axial passage along said elongated core barrel;
(b) a core receiving sleeve having forward and rear ends immovably and releasably located in said axial passage within said bullet, said core sleeve being removable from said bullet following retrieval of said bullet;
(c) first shoulder means in said axial passage for locking said sleeve forward end;
(d) second shoulder means in said axial passage for locking said sleeve rear end;
(e) said passage having a rearward extent longer than said sleeve to form an area to receive material other than a formation core sample, said passage extending along said core barrel;
(f) vent passage means extending away from the rearward extent of said passage to enable venting of materials upon entry of a formation core sample into said sleeve;
and
(g) means enabling said sleeve to be released from said core barrel with a core sample therein, and also enabling subsequent reinstallation of said sleeve in said core barrel in locked relationship to said first and second shoulder means.

5 more elements

Dependencies are inferred from the claim text.