Slimdril International, Inc.

Steven W Drews

Albert E Roos, Jr

William J McDonald

Roger C Leaf

Frederick J Pittard, Jr

A flexible steering sub is disclosed for flexible drilling of horizontal oil and gas wells, horizontal storage wells, geothermal drilling for electric power generation; earth sciences study of and monitoring of earth movement with respect to fault movement; environmental science cleaning up of inaccessible polluted areas; coring to test rock strength prior to large scale constructions such as dams; introduction of chemicals for solution mining logging while drilling short radius well bores, and the like. The flexible sub comprises an elongated housing having a plurality of housing sections connectable at one end to an orientation sub for a PDM drill and connectable at the other end to a wire line connector. An electronics assembly including guidance directional guided sensors, directional probe and logging while drilling probe is positioned in a plurality of the housing sections, interconnected electrically, and connected at one end to the wire line connector. An articulated sinker bar and an articulated housing section spaced along the length of the housing and operable to bend in preference to bending of the housing sections containing the electronics assemblies. The steering sub is operable during drilling to bend along its length at the said articulated sinker bar and said articulated housing section on a short radius without bending the electronics assembly.

Steering sub for flexible drilling

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.

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Houston, TX, United States of America

Steven W Drews