Abstract: In the representative embodiment of the present invention disclosed herein, a well bore flowmeter is provided with a fluid-driven spinner which is uniquely mounted on the closed end of a hollow shaft that is coaxially disposed over a spindle and rotatably journalled thereon by one or more bearings located in the enclosed annular chamber defined between the shaft and the spindle. To protect the bearings, the chamber is filled with a lubricant and the chamber is communicated with the exterior of the flowmeter only by way of a multi-directional passage which effectively serves to block the entry of well bore debris as the flowmeter is operating. As a further protection for the bearings, one or more valve members are also preferably provided for blocking communication with the bearing chamber as the flowmeter is moved into and out of a well bore. These valve members are preferably actuated by the extension and retraction of a centralizer provided for centering the flowmeter as it is operated in a well bore.

Abstract: New and improved methods and apparatus exemplifying the present invention are disclosed herein for measuring the changes in total elongation of a drill string due to variations in the tensional forces acting thereon during a typical well drilling operation on a floating platform, measuring the changes in the total length of the drill string as it is moved into and out of the borehole from the platform, and measuring the changes in the position of the platform in relation to the upper end of the drill string which are caused by wave motion. Thereafter, these measurments are uniquely combined for producing an output signal which is representative of the changes in the borehole depth. The combined measurements are also converted for producing another output signal which is representative of the actual rate of penetration of a drill bit coupled to the drill string.