Abstract: A method for monitoring structural changes in a binder in contact with a solid object, while the binder is curing. Conductivity measuring pick-ups are placed in the binder mass and at the boundary between the binder and the solid object. A low amplitude AC voltage is applied to each pick-up at a low frequency, and the pick-up output signals are compared by a differential inductive bridge. The difference between the output signals is indicative of the extent of adhesion of the binder to the solid object. Preferably, only those components of the pick-up signals which are in phase with the applied AC voltage are employed for the comparison.

Abstract: A device for the transfer of plugging and grouting materials to, and their processing at, a pre-set level in a well comprises a pipe container which is rigidly mechanically connected by means of series installed limiter and cylinder to a drilling string. In the lower part of the pipe container, which is stopped by a plug, is installed a splitter and in the upper part, above waterproofing envelopes, is installed for axial movement along the pipe container a main piston having a rod to which is rigidly secured a retainer engageable with the limiter, and an auxiliary piston installed in the cylinder for axial movement therein, which is hydraulically coupled to the drilling string. The retainer is provided on the rod at a distance from the main piston to retain the main piston in its lowermost position immediately above the splitter.

Abstract: A device for applying plugging mix to well walls comprises installed in series and interconnected a piston having passages for the flow of a fluid and spring-biased locking members for fixing the position of the device with respect to a drilling string, and a head carrying vanes for applying plugging mix to well walls and a bit for drilling-off the mix installed at the distal end of the head. The head has passages for the flow of the fluid. The vanes are made in the form of two plates installed on opposite sides of the head at an angle with respect to its axis of rotation, the vanes being radially movable with respect to the axis of rotation. The piston, the head and the bit are of a diameter which is slightly smaller than the nominal inside diameter of the drilling string.

Abstract: A method for preparing a plugging material of an alumina-base cement, by mechanical stirring of alumina cement with additives of the pre-rated quantities to improve the physical and mechanical characteristics of the plugging material. The stirring is effected by magnetized working bodies in an alternating electromagnetic field. The resultant material is subjected to a batch forming by compression at a pressure between 50 and 120 MN/m.sup.2.

Abstract: An arrangement for full hole drilling, wherein a drilling bit having a passage for drilling fluid is attached to a drill pipe string. A hole wall former is provided above the bit for closing the space between the hole walls and the drill pipe string. A container containing a plugging material is provided in the interior of the drill pipe string immediately above the bit, which is adapted to let drilling fluid between the walls of said container and said drill pipe string. The bit has an axial bore of a diameter which is greater than the inside diameter of the container and which is adapted to receive the lower end of said container.

Abstract: An apparatus for the activation of cement comprises at least one electromagnetic particle size reducer having a common reducer hopper at the inlet ensuring a gravity feeding of cement to the reducer, and a series sequence including a receiving hopper having a crusher and a conveying screw in a casing having a classifier in the form of a screen arranged at the outlet of the screw and communicating with the reducer hopper having an inclined bottom wall, the screen of the classifier comprising a body of revolution which is rigidly secured to the shaft of the screw coaxially with the shaft and arranged together with a portion of the screw and casing inside the reducer hopper upstream the inlet of the electromagnetic reducer.

Abstract: A rapid-setting dry packing mix for eliminating bore hole troubles contains: 40 to 50 percent by weight of cement powder, 50 to 60 percent by weight of gypsum or alabaster, 0.01 to 3.0 percent by weight of barium hexaferrite powder in particles commensurate in size with those of the binder.A method for manufacturing the rapid-setting dry packing mix for eliminating bore hole troubles consists in a mechanical mixing in an alternating electromagnetic field powders of cement, gypsum or alabaster and barium hexaferrite taken in required proportions, the above barium hexaferrite powder being introduced through abrasion of working tools which are magnetized pellets prepared on the basis of barium hexaferrite.

Abstract: A plug for eliminating troublesome zones in wells, comprising a plugging agent in the form of a dry quick-setting mixture packed in an elastic water-proof cylindrical chamber having the same diameter as the well being treated and whose bottom end is stoppered, whereas the top end thereof is provided with retainers and is shaped as a double strip formed by the walls of the cylindrical chamber and defined by two peripheral longitudinal seams running to the boundary line of the plugging agent, said strip being bent along said boundary line over the plug body so as to be forced thereagainst by said elastic retainers.