Steering sub for flexible drilling

Abstract

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.