SIDEWALL ROTARY CORING TOOL

A sidewall coring tool for wireline use in an earth bore hole is provided which includes an elongated tool body adapted for suspension within the bore hole by the wireline cable at a selected depth, low speed high torque rotary coring bit apparatus mounted within the elongated tool body and cooperating therewith for advancing and retracting a rotary coring bit transversely therefrom for drilling and recovering a large core sample from the sidewall of the bore hole, and decentralizing arm apparatus mounted in the tool body on the side opposite the side of the body from which the rotary coring bit is advanced, the decentralizing arm apparatus spaced above and below the location of the rotary coring apparatus for deploying decentralizing arms from the tool body into contact with the bore hole walls and forcing the side of the tool body from which the rotary coring bit will be advanced into contact with the bore hole wall and for maintaining the tool body in rigid contact during the coring operation. In addition, the sidewall rotary coring tool further includes an electrical control circuit disposed on the earth's surface for permitting control of preselected functions of the rotary coring apparatus, and monitoring apparatus and circuitry disposed in the tool body and cooperating with the rotary coring bit apparatus for permitting continuous surface visual indication of the travel of the coring bit with respect to the tool body during the coring operation.