Abstract: At least one transmitting coil 1 and at least one receiving coil 2 are disposed along the bore axis 18 of a borehole 7 such that these coils are inclined and face each other, thus causing these coils to have directivity for examining electric characteristics of a formation around the borehole. More specifically, a method of and an apparatus for directional induction logging are provided, which permit measurement of the electric conductivity distribution of a formation in the circumferential direction in a range of several meters around the borehole and also imaging reflecting the electric conductivity.

Abstract: A speed detection apparatus intended to be placed in a borehole containing high temperature flowing fluid consists of an elongated casing with a rotary shaft having a helical rotary blade in the casing. Secured to the rotary shaft is a sensor control rotor with a plurality of metal targets on the periphery. Opposed to these targets is an eddy currents displacement transducer with electric circuitry including a coil. The displacement of the targets due to fluid flow causes impedance change in the coil which produces an electrical signal proportional to the rate of flow.

Abstract: A cable connection head is disclosed, in which a well logging cable is inserted through an upper head housing of a head housing consisting of a lower head housing coupled to an upper portion of a measuring instrument housing and the upper head housing coupled to an upper portion of the lower head housing, armoring wires of the well logging cable secured to the upper head housing, and core wires of the well logging cable are connected to a connector which is fittedly secured to the lower head housing. A metal covered cable of the well logging cable is constructed by accommodating a plurality of core wires and filling with an electric insulating material in a metal tube. The lower head housing and metal covered cable are reliably sealed to each other such as to be able to withstand high temperature by inserting the metal tube of the metal covered cable through the lower head housing and securing the metal tube by means of welding around the entire outer periphery to the top of the lower head housing.