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.

Abstract: In the preferred and illustrated embodiment of the core sample bullet construction, a multi-piece construction is set forth. There is a forward, or removable, nose portion. It nests with and connects to a carrier portion. The two portions together define an elongate central bore formed in multiple portions, and the bore is open through the rear of the carrier. At the rear, a separate and removable bottom cap is plugged into the carrier portion and the two are joined together at the time of assembly, before firing. A release ring is included on the outer face of the nose portion and protects the shoulder of the carrier portion, engaging the formation upon entry, and is sacrifically abandoned; the ring is a mechanism for releasing the nose portion whereby retraction is easily obtained; the release ring includes drilling mud and debris relieving notches formed in the inside diameter.

Abstract: Sampling bullets of the type which are fired into rock formations adjacent a well bore. Surprising and unexpected increases in the service life of the bullet and reliability in obtaining and retrieving core samples have been achieved.