Schlumberger Technology Corporation

Jean C Lavigne

Yves Nicolas

Gerard Bouguyon

Gerard Segeral

Pierre Chesnel

Andre Landaud

M Bosse Platiere

The invention relates to a well perforation device comprising a support (25) and encapsulated shaped charges (26) fixed unidirectionally on this support, usually on the back side of a support bar whose front side is to be applied against the casing. Positioning rings (35, 36) are snapped onto the charges (26) at regular intervals along the support (25). These rings have a rounded external surface on which the perforation device can swivel up to a correct balanced position for which the front sides of the charges are applied against the casing (13).

Well perforation device

A depth measurement system produces independent signals, each presumably corresponding to the same movement of a wireline if produced under ideal wireline measurement conditions. The system utilizes the signals to provide an accurate and repeatable signal under varying wireline measurement conditions and is particularly suitable for driving a recorder for depth recording and merging measurements from tools lowered in the borehole on different runs and to detect slippage between the wireline and a tangential wheel used to provide one of the signals. Slidably mounted measurement wheels insure tangential engagement of opposite sides of the wireline with equal pressure. Low-load signal generators each responsive to the rotation of the opposing wheels provide independent signals, each ideally corresponding to the movement of the wirline engaged between them. Magnetic marks written on the wireline are sensed and provide yet another independent signal. Automatic processing of these signals provides alarms and corrections for slippage, variations in measurement tension, and cable stretch.

Method and apparatus for providing repeatable wireline depth measurements

In the representative embodiment of the new and improved apparatus disclosed herein, a so-called 'stuck-point indicator' or 'freepoint-indicator' tool includes a deformation-responsive sensor tandemly supported between upper and lower hydraulically-operated tool anchors cooperatively arranged to be sequentially engaged with longitudinally-spaced wall portions of a string of well pipe believed to be stuck in a well bore. In the preferred embodiment of the tool, each tool anchor respectively includes a piston actuator which, upon application of a predetermined pressure as developed by a hydraulic-control system on the tool, operates to retract a set of movable anchoring elements and, upon a reduction in that hydraulic pressure, is biased by a spring to extend the anchoring elements. To assure sequential operation of the upper and lower anchors, the hydraulic-control system of the tool further includes a flow restrictor for cooperatively delaying the reduction of the hydraulic pressure acting to retain the lower anchoring elements in their retracted positions until such time that the upper elements are moved into anchoring engagement with the pipe wall.

Methods and apparatus for determining the stuck point of a conduit in a

In the representative manner of practicing the new and improved method disclosed herein, a so-called 'stuck-point indicator' or 'freepoint-indicator' tool including a unique deformation-responsive sensor tandemly arranged between unique upper and lower tool anchors is positioned in a string of well pipe believed to be stuck in a well bore. The tool is then moved to a selected depth location in the pipe string and, in keeping with the principles of the present invention, operated so that the upper anchor is engaged with the pipe string wall before the lower anchor is engaged. Thereafter, upon application of forces to the upper end of the pipe string, independent measurements are produced by the sensor which are respectively representative of tensional forces and torsional forces acting on that portion of the pipe string between the upper and lower anchors.

Methods for determining the stuck point of a conduit in a borehole

In the representative embodiment of the present invention disclosed herein, this new and improved perforating apparatus includes a unique elongated carrier strip of a ductile steel carrying encapsulated shaped explosive charges having their forward ends fitted and snugly secured against the concave rear face of the strip by means of externally-threaded axial projections respectively threaded into tapped charge-mounting holes closely spaced along the carrier. The forward face of the carrier strip and the rear portions of the capsules are complementally shaped for accommodation within a given size of well bore piping thereby allowing the largest-possible mass of explosive to be disposed in each capsule. To assure that the new and improved perforating apparatus can be used safely in gas-filled well bores without risking either severe distortion or breakage of the carrier, additional openings are arranged in the strip between adjacent charge-mounting openings and cooperatively sized for preferentially inducing a minor transverse bend in the strip across each of these additional openings upon detonation of the adjacent charges instead of allowing the carrier to be severely bent in a substantially-uninterrupted arc or exaggerated bow along its full length.

Growing community of inventors

Chevreuse, France

Jean C Lavigne