ROTARY STEERABLE PUSH-THE-BIT DRILLING APPARATUS WITH SELF-CLEANING FLUID FILTER

摘要

A steerable drilling apparatus includes a control system (50) inside a cylindrical housing (10) connected to a drill bit having radially- extendable pistons (40). A fluid-metering assembly directs a piston- actuating fluid into fluid channels leading to respective pistons (40). The control system controls the fluid-metering assembly to allow fluid flow to selected pistons (40), causing the actuated pistons to temporarily extend in the opposite direction to a desired wellbore deviation, thereby deflecting the drill bit away from the borehole centerline. An upper member in the fluid-metering assembly can be moved to stabilize, steer, and change TFA (total flow area) within the drill bit. The control system and drill bit are connected so as to facilitate removal to change the drill bit's steering section and cutting structure configuration or gauge simultaneously. The apparatus may incorporate a fluid filter module mounted to the control system. The pistons may incorporate auxiliary cutting elements to provide near-bit reaming capability.