Methods, systems, and computer-readable medium to perform operations for identifying fracture barriers in a well. The operations include converting rebound hardness values of a rock specimen from the well to unconfined compressive strength (UCS) values, where each of the rebound hardness values corresponds to a respective coordinate of a measurement grid imposed on the specimen. The operations further include, for each column of the grid, plotting the UCS values versus depth. Further, the operations include mapping, based on a maximum UCS value and a minimum UCS value, a relative strength contour plot for the specimen. Yet further, the operations include mapping, based on a fixed strength range, an absolute strength contour plot for the specimen. In addition, the operations include determining, based on the relative strength contour, the absolute strength contour, and mineralogy of the rock specimen, that the rock specimen is indicative of a fracture barrier in the well.

A controller of a hardness tester can determine, in a condition where a driver is not in operation and when a spring displacement detector and an arm displacement detector detect an amount of displacement of respective objects (plate spring and loading arm), that a loading arm and a plate spring are deformed according to changes in environmental temperature. A favorable hardness test can be performed by the hardness tester corresponding to the environmental temperature according to the determination by carrying out an initialization process that resets the displacement amount of respective object to zero, the displacement amount detected by the spring displacement detector and the arm displacement detector respectively.

An apparatus includes a holder to support an indenter relative to a sample of material, a depth sensor, and a controller to execute instructions for performing operations. The operations include controlling the holder to apply a first force on the sample with the indenter and determining a first depth of the indenter based on first data generated by the depth sensor, controlling the holder to move the indenter from the first depth to a predetermined depth greater than the first depth, after the indenter is moved to the predetermined depth, controlling the holder to apply the first force on the sample with the indenter and determining a second depth of the indenter based on second data generated by the depth sensor, and determining a value indicative of hardness of the sample based on a difference between the first depth and the second depth.

A heated or cooled sample holding stage for use in a nanoindentation measurement system is described. The geometry of the design and the selection of materials minimizes movement of a sample holder with respect to a nanoindentation tip over a wide range of temperatures. The system controls and minimizes motion of the sample holder due to the heating or cooling of the tip holder and/or the sample holder in a high temperature nanoindentation system. This is achieved by a combination of geometry, material selection and multiple sources and sinks of heat. The system is designed to control both the steady state and the transient displacement response.

A heated or cooled sample holding stage for use in a nanoindentation measurement system is described. The geometry of the design and the selection of materials minimizes movement of a sample holder with respect to a nanoindentation tip over a wide range of temperatures. The system controls and minimizes motion of the sample holder due to the heating or cooling of the tip holder and/or the sample holder in a high temperature nanoindentation system. This is achieved by a combination of geometry, material selection and multiple sources and sinks of heat. The system is designed to control both the steady state and the transient displacement response.

An apparatus for performing a contact mechanics test in a substrate includes a stylus having at least two contact elements. Each contact element has a contact profile, and the contact elements are disposed in the stylus to define a stretch passage therebetween. The stylus is configured to deform the substrate so as to cause the substrate to flow between the contact elements and induce tension in the substrate in order to generate and preserve micromodifications in the substrate. Methods of performing a contact mechanics test using the apparatus are also provided.

An apparatus for performing a contact mechanics test in a substrate includes a stylus having at least two contact elements. Each contact element has a contact profile, and the contact elements are disposed in the stylus to define a stretch passage therebetween. The stylus is configured to deform the substrate so as to cause the substrate to flow between the contact elements and induce tension in the substrate in order to generate and preserve micromodifications in the substrate. Methods of performing a contact mechanics test using the apparatus are also provided.

A polyimide film, which is a reaction product of a diamine including an amide structural unit in an amount of greater than about 0 mol % and less than or equal to about 80 mol % and an aromatic dianhydride, wherein the polyimide film has a Martens hardness of about 14 N/mm.sup.2 to about 120 N/mm.sup.2 at a thickness of about 30 m to about 100 m.

A polyimide film, which is a reaction product of a diamine including an amide structural unit in an amount of greater than about 0 mol % and less than or equal to about 80 mol % and an aromatic dianhydride, wherein the polyimide film has a Martens hardness of about 14 N/mm.sup.2 to about 120 N/mm.sup.2 at a thickness of about 30 m to about 100 m.

Devices and methods are described for evaluating tubulars installed in a wellbore, which permit detection of wellbore construction errors. Errors in the hardness or grade of the material installed, e.g., in critical wellbores, could potentially affect the integrity of the wellbore and lead to catastrophic effects with respect to well control, pipe connection failure while running casing down-hole, or pipe body failure due to buckling or axial/triaxial failure during stimulation and production. Once tubulars are installed, the devices and methods permit testing the hardness of the steel or other material forming the tubulars. Determining the hardness of the tubulars may provide assurances or indications that remedial action may be appropriate to secure the wellbore. The devices and methods can be implemented to deliver a down-hole Rockwell hardness test in connection with logging while drilling technologies, with wireline tools, or in connection with other deployment mechanisms.