Abstract: A tool for housing a magnetic directional survey instrument for inserting the instrument into a deviated well bore. Means are provided on the tool for circulating well fluids past the tool while it is in the well bore. There is provided means, connectable on the tool, for centering the tool in the vertical, as well as the deviated portion of a well bore.

Abstract: A guide for drilling a straight section of a bore hole deflected from the vertical. The apparatus comprises either a normally straight or a curved-straight tubular member which has a plurality of generally circumferential cuts disposed along the length of the guide. The cuts allow the guide to be bent sufficiently to enter and traverse a short radius curve and then return to its normal configuration for guiding the drilling of the straight portion of the deflected bore hole. A clutch mechanism disposed in the drill guide permits engagement of the guide by the drill string for orientation of the guide.

Abstract: A flexible pipe adapted for connection in a drill string, having sufficient wall thickness in order to withstand forces imposed by drilling a well. The flexible pipe has a plurality of improved, essentially circumferential cuts, each cut being through the wall thickness of the pipe. The cuts provide a pipe having a plurality of dovetail teeth and complimentary recesses on each end of the intermediate segments. The teeth on one segment are positioned in the recesses and interlocking with the teeth of the adjacent segment. Each side of each tooth consists of two reversed, intersecting semicircles. The tooth and recess interlock has sufficient clearance to form a joint which has limited relative movement in any direction between the segments.