A method for estimating wear of a drill bit in percussive rock drilling. A percussion device is configured for generating shock waves in a drill bit for breaking rock. The method includes, during drilling determining a percussion frequency of the percussion device; and estimating wear of the drill bit based on the determined percussion frequency of the percussion device and a model representation of the wear of the drill bit as a function of percussion frequency, wherein the model representation is configured to output the estimated wear of the drill bit utilizing the determined percussion frequency as input signal.

Methods and systems for determining whether a base oil for use in drilling muds will be compatible with cement during subsequent cementing operations include: providing a drilling fluid that includes a base oil; using the drilling fluid to drill at least a portion of a wellbore penetrating at least a portion of a subterranean formation; measuring a compositional characteristic of the base oil using one or more analytical tests; determining whether the base oil is a compatible base oil or an incompatible base oil based at least in part on the compositional characteristic of the base oil; injecting an amount of spacer fluid into the wellbore, wherein the amount of spacer fluid is selected based on the determination of whether the base oil is a compatible base oil or an incompatible base oil; and injecting the one or more cementing or completion fluids into the wellbore.

A logging tool electronics system is disclosed with noise minimization features and pulse compression signal processing techniques to improve the signal-to-noise ratio of array induction logging tools. The borehole is radiated with a magnetic field produced by a configurable multi-frequency and/or multi-amplitude sine wave signal stimulus section driving a fully differential single transmitter coil. Received signals from multiple mutually balanced fully differential receiver arrays are processed by receiver signal chains using adaptive algorithms under firmware control. The received signals are used to determine the conductivity and resistivity of the formation surrounding the borehole.

A fastener driving workhead unit is provided for performing an operation on spikes of a railroad track having a plurality of ties, and includes a hammer housing configured for accommodating a hammer, the housing being attached to a hammer bushing having a hammer bushing clamp. Also included in the workhead unit is an anvil assembly having an anvil and an extension coupler, the extension coupler being releasably secured to the hammer bushing by fastening the hammer bushing clamp. Further, the workhead unit includes a jaw assembly having a jaw block, the jaw block having at least one jaw block clamp for releasably securing a guide rod to the jaw block by the jaw block clamp, such that the anvil freely reciprocates in the hammer housing for driving the spikes into the plurality of ties.

A percussion unit for a rotary hammer and/or percussion hammer includes a control unit that is configured for open-loop and/or closed loop control of a pneumatic percussion mechanism. In at least one operating state in which the control unit changes from an idle mode to a percussion mode, the control unit is configured to adjust at least one operating parameter temporarily to a starting value.

A drill string rod and a drill string assembly includes a drill rod and a drill bit. The rod includes a threaded male end and a female end. An axially extending shoulder is provided at the male end and has an axial length greater than an outside diameter of the shoulder to provide a shoulder driven rod exhibiting enhanced guidance to achieve straighter holes and better collaring.

A hydraulic hammering device includes a piston front chamber and a piston rear chamber defined between an outer circumferential surface of the piston and an inner circumferential surface of the cylinder and disposed separately from each other at front and rear, respectively, in an axial direction. A switching-valve mechanism drives the piston by switching at least one of the piston front chamber and the piston rear chamber into communication with at least one of a high pressure circuit and a low pressure circuit. An acceleration piston is disposed behind the piston and is configured to come into contact with the piston during a retreat stroke thereof to urge the piston forward, in which a timing where the acceleration piston itself starts to come in contact with the piston is set to be earlier than a timing where the piston is braked by the switching-valve mechanism.

A drill string section of a drill string for drilling in the ground having arranged on the outside of the drill string section at least one marking by means of which abrasion can be recognized.

A drill string section of a drill string for drilling in the ground having arranged on the outside of the drill string section at least one marking by means of which abrasion can be recognized.

A method of separating gas from a fluid mixture in a production stream of a well where the method includes using an outer tube and an inner tube positioned concentrically with the outer tube to separate gas and liquid from a mixture. The production stream is directed through the outer tube and into a space between a well casing of the well and the outer tube where gas in the production stream can separate from fluid in the production stream. The separated fluid is then directed through the inner tube to a pump.