Apparatus for arcuate drilling

Abstract

A system of apparatus for arcuate drilling into the earth is disclosed which comprises a drill string extending into a well bore in the earth and a fluid operated drill motor and drill bit operated thereby secured on the bottom end of the drill string. The drill motor is connected at its upper end to the drill string and at its lower end to the drill bit for rotating the drill bit independently of rotation of the drill string. The drill motor has a tubular drive section housing constructed of non-magnetic material, preferably a Beta-C titanium alloy containing titanium, aluminum, vanadium, chromium, zirconium and molybdenum in the proportions Ti-3Al-8V-6Cr-4Zr-4Mo. The longitudinal axis of the drill motor housing has its upper and lower ends angularly displaced from the longitudinal axis of its central portion end for directing the axis of rotation of the drill bit such that it is angularly displaced from the axis of the drill string for effecting a curved path for the wellbore. An orienting/circulating/float sub constructed of non-magnetic material, preferably Beta-C titanium alloy, connected above the drill motor. A drill collar constructed of non-magnetic material, preferably Beta-C titanium alloy, is connected to the upper end of the orienting/circulating/float sub. The drill collar may be of a one-piece Beta-C titanium alloy with integral threaded ends or may have separate threaded end pieces of steel or Beta-C titanium alloy welded thereon. A survey tool is positioned in and surrounded by the orienting/circulating/float sub. A drilling rig, instruments and controls positioned on the earth surface and connected by wire lines and a wet connect to the survey tool. The structure and configuration of the respective components cooperate to facilitate bending through a radius of curvature as short as 20 feet.