Orienting and circulating sub

Abstract

An orienting and circulating sub is disclosed for connection in an apparatus for angular drilling in the earth. The drilling apparatus comprises a drill string extending into a substantially vertical well bore in the earth supporting a fluid operated motor and drill bit at its lower end. The drill bit is supported for angular drilling by either using a bent sub for supporting the drilling motor or be using a drilling motor with a bent housing. A surveying tool is connected above the motor for determining and controlling the direction of drilling. A mule shoe keying sub is connected to the surveying tool for orienting the position of the motor in relation to said surveying tool. The orienting sub comprises a tubular housing formed in two sections threaded together with one end connected to the surveying tool by the mule shoe keying sub and the other end connected to the bent sub or to the bent motor housing. The orienting sub has a sleeve mounted in the end of the lower housing section with a key for receiving the mule shoe for locating the sub in relation to the surveying tool. The sleeve is oriented in the housing by a system of fine grooves and splines on the sub section and on the sleeve which permit fine angular adjustment. A modified Baker float valve is positioned in the lower end of the tool with a flapper check valve. A piston valve with shear pin is provided to open a bypass valve for draining the drill string during lifting.