A method for limiting the speed of a hoist mounted to a mobile well service rig involves determining a safe speed limit that ensures the hoist's capable stopping time is less than the maximum allowed time for stopping. In some examples, the maximum allowed time for stopping is based on the wellstring's modulus of elasticity and independent of the hoist's braking characteristics. The capable stopping time, however, is independent of the wellstring's modulus of elasticity and dependent on the hoist's braking characteristics.

A method for limiting the speed of a hoist mounted to a mobile well service rig involves determining a safe speed limit that ensures the hoist's capable stopping time is less than the maximum allowed time for stopping. In some examples, the maximum allowed time for stopping is based on the wellstring's modulus of elasticity and independent of the hoist's braking characteristics. The capable stopping time, however, is independent of the wellstring's modulus of elasticity and dependent on the hoist's braking characteristics.

The invention relates to a construction machine, in particular drilling rig, comprising a mast, along which a tool is movably mounted, wherein the tool is suspended on a cable which can be actuated by means of cable winch for raising and lowering the tool, which cable winch is driven by an electric motor, as a winch drive, in a drive mode, wherein the electric motor is designed for operating in a recuperation mode in which the electric motor preferably generates electrical energy when the tool is lowered and outputs said electrical energy to an energy store, and a controller, which is designed to actuate the electric motor, depending on a specifiable target value, in such a way that the cable is tensioned both in the drive mode and in the recuperation mode of the electric motor.

A method for controlling a hydraulic winch includes acquiring measurements from sensors coupled to the hydraulic winch. A first control function is computed based on the measurements. The first control function sets pressure across a variable displacement motor that produces motion of the tool string following a desired motion trajectory. A second control function is computed. The second control function sets displacement of a variable displacement pump that causes the pressure across the variable displacement motor to track the first control function. A pump command is selected based on the second control function. The pump command is transmitted to the variable displacement pump. The tool string moves responsive to the pump command.

A method for controlling a hydraulic winch includes acquiring measurements from sensors coupled to the hydraulic winch. A first control function is computed based on the measurements. The first control function sets pressure across a variable displacement motor that produces motion of the tool string following a desired motion trajectory. A second control function is computed. The second control function sets displacement of a variable displacement pump that causes the pressure across the variable displacement motor to track the first control function. A pump command is selected based on the second control function. The pump command is transmitted to the variable displacement pump. The tool string moves responsive to the pump command.

A trigger mechanism is provided for a passive rotating jointed tubing injector having gripper blocks for moving connected, segmented oilfield tubulars axially into or out of horizontal, extended-reach oil and natural gas wells that may contain pressurized fluid or gas to complete for production, work over and service the wells, utilizing an operation commonly known as snubbing. The trigger mechanism can open the gripper blocks when a tapered upset section of increasing diameter on the tubulars is encountered that would not otherwise fully open and operate the gripper blocks.

A trigger mechanism is provided for a passive rotating jointed tubing injector having gripper blocks for moving connected, segmented oilfield tubulars axially into or out of horizontal, extended-reach oil and natural gas wells that may contain pressurized fluid or gas to complete for production, work over and service the wells, utilizing an operation commonly known as snubbing. The trigger mechanism can open the gripper blocks when a tapered upset section of increasing diameter on the tubulars is encountered that would not otherwise fully open and operate the gripper blocks.

An automated pipe tripping apparatus includes an outer frame and an inner frame. The inner frame includes a tripping slips and iron roughneck. The automated pipe tripping apparatus may, in concert with an elevator and drawworks, trip in a tubular string in a continuous motion. The tripping slips and iron roughneck, along with the inner frame, may travel vertically within the outer frame. The weight of the tubular string is transferred between the tripping slips and the elevator. The iron roughneck may make up or break out threaded connections between tubular segments, the upper tubular segment supported by the elevator and the lower by the tripping slips. An automated pipe handling apparatus may remove or supply sections of pipe from or to the elevator. A control system may control both the automated pipe tripping apparatus and the elevator and drawworks.

An automated pipe tripping apparatus includes an outer frame and an inner frame. The inner frame includes a tripping slips and iron roughneck. The automated pipe tripping apparatus may, in concert with an elevator and drawworks, trip in a tubular string in a continuous motion. The tripping slips and iron roughneck, along with the inner frame, may travel vertically within the outer frame. The weight of the tubular string is transferred between the tripping slips and the elevator. The iron roughneck may make up or break out threaded connections between tubular segments, the upper tubular segment supported by the elevator and the lower by the tripping slips. An automated pipe handling apparatus may remove or supply sections of pipe from or to the elevator. A control system may control both the automated pipe tripping apparatus and the elevator and drawworks.

A portable winch and method of use is shown. One advantage of winches shown includes an ability to lower a boom or boom sections into limited access exit pit for winching operations such as pipe bursting. Sectional boom designs shown provide the ability to easily raise and lower a boom large distances without the need for a single long boom. Selected winch designs shown include flexible inserts between the boom and the winch frame that help resist damage from unforeseen shifting of the device during operation. Designs and methods shown also include multiple pulleys on a boom end unit. Fasteners are shown that reduce build up of debris.