Abstract: An apparatus for drilling a sidewall core from a borehole which has a cylindrical housing with an opening through which a core bit and barrel are extended and retracted. In a preferred embodiment there is a fixed plate on opposite sides of the bit motor with guide slots cut therethrough. A drive plate is provided adjacent each fixed plate having guide slots. The bit motor has two pins on each side which extend through the guide slots of the drive plate. Movement of the drive plates causes the bit motor to follow the designated path.

Abstract: This relates to sidewall coring tools used to obtain samples of the formation through which the wellbore is drilled. It includes a housing which supports a guide means along which the drill bit, core barrel and motor can be moved to extend or retract the cutting bit and core barrel along a selected path. The core barrel is retracted inwardly on a horizontal path and tilted in an upward position such that the outer end of the core barrel is higher than the end near the motor. Means are provided to force the cut core from the barrel into a core container in association with indexing means.

Abstract: This invention relates to an apparatus for cutting cores from the sidewall of a borehole after the borehole has been drilled. The apparatus includes an elongated housing which supports guide means which provides a path along which a core bit and motor can be moved to extend and retract the core bit. The guide means has a rotational control section and a transverse control section. The rotation control section guides the motor and its core bit from an upright position in the housing to a selected angle and the vertical transverse control section guides the coring bit means in the direction of the formation.

Abstract: An apparatus operable on a wireline logging cable for drilling a hole in the sidewall of a drill hole which comprises a hydraulically operated backup shoe for wedging the apparatus at a selected location in the drill hole, a hydraulic motor with a drilling bit connected thereto for rotation by the hydraulic motor and hydraulic means connected to the hydraulic motor for moving the bit into drilling engagement with the sidewall of the drill hole. In the improvement of this invention, the hydraulic means for moving the bit into drilling engagement comprises a new flow restrictor valve. This flow restrictor valve has an orifice and a slender pointed rod for restricting the flow of fluid through the orifice. Opposing spring means and control fluid means engage the rod for controlling its movement toward and away from the orifice.