Abstract: The invention is an electronic wire length measuring apparatus for accurately measuring and indicating the height of a traveling block above a fixed reference point in oil well drilling applications where a traveling block is hooked to a cable and pulley arrangement and to a winch drum, said winch drum being used to vary the height of the traveling block. The wire length measuring apparatus produces an output visual indication of the height of the traveling block independent of variations in drum size, wire size, number of layers on the drum, and the weight load on the traveling block, which causes a lower actual traveling block position due to stretching in the wire.

Abstract: In an offshore oil well system wherein a floating well platform is connected through a telescoping cylindrical member to a marine riser extending down to the drilling area, the telescoping cylindrical member being mounted for slidable, sealable movement within the top of the marine riser, said movement occurring as a result of heave of the floating platform due to wave and tide action, a drilling fluid compensator for compensating for a change in the flow of drilling fluid out of the telescoping cylindrical member into the return system.

Abstract: Apparatus adapted to compensate for the heaving of a floating offshore drilling platform, which heaves relative to the ocean bottom due to wave action of the water in which the platform is floating, which heave-compensation apparatus is adapted to be connected to apparatus for measuring the rate of penetration of pipe run into a well beneath the floating platform. The heave-compensating apparatus nullifies the effect of movement of the drilling platform relative to a stationary object, such as a riser pipe beneath the platform, so that false or erroneous reading on the rate of penetration measuring apparatus is prevented.