Abstract: Bore hole underreamer in a terrestrial formation, intended in particular for oil drilling and especially to be fixed in the vicinity of a drill head, the underreamer having a hollow body (1), with a longitudinal axis (3), which has an external wall (5), at least two cylindrical bores (7) provided through the external wall (5) and whose axes (9) are transverse to the longitudinal axis (3), the bores being distributed over the circumference of the hollow body, and in each of the bores, a cylindrical widening arm (11) which has a cutting end (13), disposed on the outside of the body and provided with blades (15) for widening the hole, which is arranged in the bore like a hydraulic piston, so as to be able to slide therein between an active position in which this cutting end (13) is distant from the body, and an inactive position, and whose other end, inside the body, is intended to receive from a fluid a pressure capable of pushing the said arm into its active position, the underreamer having a locking member (2

Abstract: Provided is a bore hole underreamer in a terrestrial formation, intended in particular for oil drilling. The underreamer has a hollow body and at least two cylindrical bores. The bores are provided through an external wall of the body and have axes that are transverse to a longitudinal axis of the body. The bores are distributed over the circumference of the hollow body and each bore contains a cylindrical widening arm. Each arm has a bladed cutting end disposed on the outside of the body that slides between active and inactive positions. Another end of each arm is disposed inside the body and receives fluid pressure for pushing the arm into the active position. The underreamer includes a locking member for locking the arms in their inactive position when the locking member is immobilised in the body in a releasable fashion in a locking position.

Abstract: The invention concerns a core barrel, in particular for oil exploration, comprising a string, an external tube (2) fixed at the front end of the string, a core bit mounted on a front section (3A) of the external tube, and an internal tube assembly (8) mounted in the external tube and comprising hydrodynamic means transforming a core sampling line pressure into a load thrusting said assembly towards the core barrel front, the front section of the external tube being mounted axially sliding, limited by front and rear stop elements (12A, 12P), in a rear section (3P) of the same external tube to project therefrom longitudinally, the assembly comprising a support stop (14) arranged to thrust selectively forward the front section of the external tube, means being arranged between the inner tube (9) proper and said front section such that the latter can be driven in rotation about its longitudinal axis independently of said internal tube, a motor (7) capable of driving the core bit in rotation relative to the string

Abstract: A double-tube core drill wherein the inner tube (2) is connected to the outer tube (1) by a multi-element needle and/or ball bearing (11), allows for the inner tube (2) to be made rigid and prevents it from rotating along with the outer tube (1). The extraction device (9) and the inner wall (38) of the tube are preferably covered with an antifriction coating. A set of stabilizing elements (67) are spread along the outer tube to stabilize the inner tube (2). Said inner tube has a tapered shoe (32) provided with a lower bevelled lip (14). The drill also comprises a device for indicating that the core has jammed in the inner tube (2) and a sealing device (19) designed to receive a ball (46) provided for sealing the inner tube (2) of said core drill.

Abstract: The invention concerns a core barrel, in particular in the field of oil exploration, comprising at least an outer tube (2) and a core bit (3) forming an outer assembly (4) and at least an inner tube (5) forming with a drilling core optionally present therein, and optionally with part of the groups arranged under the drilling core base, an inner assembly (7), suspension and/or guiding means being provided for maintaining the inner assembly (7) inside the outer assembly (4), the suspension and/or guiding means being further arranged such that the inner assembly (7) maintains at least perpendicular to these means (9), with respect to the outer assembly (4), a predetermined axial and/or radial and/or angular freedom of movement greater than usual.

Abstract: A core sampling method, particularly for the oil industry, wherein actual core sampling is performed by means of a core sampler (1) comprising at least one Inner barrel (5), an outer barrel (2) and a bit (3), and a substantially axial compressive force (F) is exerted on the top (7A) of a core sample (7) being formed, at least during a major part of the core sampling process, said force being within a range determined particularly on the basis of the material of the core sample (7), whereafter the force (F) is removed at the latest before the core sample (7) is withdrawn from the inner barrel (5). A core sampler for carrying out the method is also provided.

Abstract: A core sampler, particularly for oil prospecting, including a coring bit (2), an outer barrel (3) for rotating the coring bit (2), and an inner barrel (5) for receiving the core sample (7) in its internal space (8) during coring, the inner (5) and outer (3) barrels being substantially coaxial, and further comprising an intermediate barrel (15) coaxially arranged between the inner (5) and outer (3) barrels and defining a first longitudinal coring fluid channel (16) with the outer barrel (3), and a second longitudinal coring fluid channel (17) with the inner barrel (5), as well as said longitudinal channels (16, 17) and valving for at least temporarily selectively causing and/or cutting off coring fluid communication between the rear end (17B) of the second longitudinal channel (17) and/or the rear end (16B) of the first longitudinal channel (16) and/or the rear end (8B) of the internal space (8).

Abstract: A core sampler, particularly for use in oil prospecting, including a flexible movable ring (5), provided in particular at the front end (2) of the core sampler, which end is connected to a coring bit (3), for grasping a core sample (C) to be brought to the surface. The ring has a cylindrical internal surface (6) to be clamped around the core sample (C), and a frustoconical external surface (7) tapering towards the front end (2). In the end or starting position, the ring (5) is exposed to zero or minimal strain from the bearing surface (12) and has an internal diameter no smaller than the outer diameter of the core sample (C) to be grasped. The core sampler (1) comprises control mechanism for longitudinally moving the movable ring (5) from the end starting position to an end clamping position. A flexible sleeve (15) is advantageously substantially coaxial with the movable ring (5) and engages the side thereof opposite the front end (2) of the core sampler (1).