Abstract: A centralizer for an oil well drill casing including at least one strip of ceramic or plastic material applied onto an outer wall of the casing.

Abstract: A centralizer for an oil well drill casing including at least one strip of ceramic or plastic material applied onto an outer wall of the casing.

Abstract: A centralizer for an oil well drill casing including at least one strip of ceramic or plastic material applied onto an outer wall of the casing.

Abstract: A centralizer for an oil well drill casing including at least one strip of ceramic or plastic material applied onto an outer wall of the casing.

Abstract: Method for the centralization of drill casings in a tight borehole, both vertical and deviated, comprising the following operations: Application on the casing section in question, of an adherence strip equipped with one or more housings and rapid adjustable lever closure; Insertion of suitable molds in the housings of which the strip is equipped; Injection into the molds of plastic material characterized by a high mechanical resistance, a high degree of surface adhesion and resistance to abrasion by friction, and also in-place elasticity, higher than the elasticity of the casings; Removal of the adherence strip once the hardening of the plastic material in the shape of the mold, has been completed.

Abstract: Method for the centralization of drill casings in a tight borehole, both vertical and deviated, comprising the following operations: Application on the casing section in question, of an adherence strip equipped with one or more housings and rapid adjustable lever closure; Insertion of suitable moulds in the housings of which the strip is equipped; Injection into the moulds of plastic material characterized by a high mechanical resistance, a high degree of surface adhesion and resistance to abrasion by friction, and also in-place elasticity, higher than the elasticity of the casings; Removal of the adherence strip once the hardening of the plastic material in the shape of the mould, has been completed.

Abstract: A method for selecting a drilling parameter is disclosed. The method includes determining a loading displacement relationship for samples of earth formations. The loading displacement measurements are made by an indenter. The drilling parameter is selected from the loading displacement relationship. In one embodiment of the invention, the loading displacement relationship is determined from cuttings made during drilling of a wellbore. The loading displacement relationship determined during drilling is used to select at least one drilling parameter during drilling to improve drilling performance. Drilling parameters which can be selected include mill tooth and/or insert bit type; type of gauge protection to be used on the bit; type, size and orientation of jet nozzles on the bit; and blade structure, cutter type and density as well as the cutter impact resistance for fixed cutter bits. Other drilling parameters include weight on bit, drill bit rotation rate, and drilling fluid flow rate.

Abstract: Method for measuring the propagation velocities of ultrasonic acoustic waves through rock fragments which includes the steps of (a) introducing the fragment in a coupling fluid between a pair of piezoelectric transducers capable of generating highly damped ultrasonic acoustic waves; (b) passing highly damped ultrasonic acoustic waves through the fragment, said waves being generated by a pulse generator with a pulse width varying from 0.1 .mu.s to 20 .mu.s; (c) visualizing the obtained electric signals by an oscilloscope with a resolution of at least 10.sup.-2 .mu.s; and (d) measuring the transit time of the waves themselves. The ultrasonic acoustic waves may be compressional or shear waves. In one embodiment the coupling fluid has a viscosity varying be 200 and 800 poises.