Abstract: A method of determining the maximum temperature undergone by a specimen of sedimentary rock during natural heating over a geological process, within the range from 60° C. to 230° C. approximately. The method includes analysis at very low temperature, down to a few kelvin, for example down to 10 kelvin, of the magnetic transitions intended to characterize an iron oxide and an iron sulfide that are formed or destroyed in the specimen by the geological heating of the sediment; and determination of the maximum temperature undergone by the specimen, using a calibration obtained by measuring the same magnetic parameters on the same sediment or on other sediments of the same nature, heated beforehand in the laboratory to known temperatures.

Abstract: A method of determining the maximum temperature undergone by a specimen of sedimentary rock during natural heating over a geological process, within the range from 60° C. to 230° C. approximately. The method includes analysis at very low temperature, down to a few kelvin, for example down to 10 kelvin, of the magnetic transitions intended to characterize an iron oxide and an iron sulfide that are formed or destroyed in the specimen by the geological heating of the sediment; and determination of the maximum temperature undergone by the specimen, using a calibration obtained by measuring the same magnetic parameters on the same sediment or on other sediments of the same nature, heated beforehand in the laboratory to known temperatures.

Abstract: The present invention relates to the processes and devices for assessing the permeability of a rock medium 1 containing a fluid 2 in its interstices 3. The device and the process according to the invention are characterized essentially in that a given magnetic field is applied to the interstitial fluid 2 located in the rock medium 1, the variation in pressure of the interstitial fluid 2 resulting from the application of the magnetic field is measured, and the permeability of the rock medium is determined as a function of the value of the variation in pressure of the interstitial fluid.

Abstract: The present invention relates to the processes and devices for assessing the permeability of a rock medium 1 containing a fluid 2 in its interstices 3.

Abstract: A method and the apparatus for in situ analysis of a rock formation that already contains fluid in its interstices an excitation device is provided for imparting motion to the fluid relative to the rock formation and the magnetic fields created by the relative motion of the fluid in the rock formation measured. The permeability of the rock formation are deduced from the measurement. The measurement system is particularly applicable to in situ measurement of the permeability of rocks, e.g. down an oil well.

Abstract: Inside a syringe (1) slides a plunger (2) which bears a joint (4) sliding sealingly over the internal wall of the syringe. The flexible membrane (6) of the joint (4) fixed to the end of the plunger (2) bears a closing component (25, 27) which follows the movement of deformation or displacement of the membrane through the effect of the pressure built up during the injection stage, but which is retained by immobilizing strips (17) in a position in which it opens the orifice, breaking the seal between the top and the bottom of the joint, as soon as the membrane returns to its initial position.

Abstract: Apparatus for continuously recording, as a function of the depth, the residual magnetization of the rocks through which a well hole passes, comprising, on the one hand, a measurement probe which contains means for measuring the magnetic susceptibility and the magnetic field and, in a cryostat, three gradiometers and, on the other hand, a processing unit which incorporates an integrator (81) for carrying out integration of the data from the gradiometers, a multiplier (76) for multiplying the magnetic field by the magnetic susceptibility, and a subtractor (83) for deducting this product from the result of the integration.