Method and apparatus for steering a drill string and reaming well bore surfaces nearer the center of drift

Abstract

A steerable well bore drilling device and method are disclosed. The steerable well bore drilling device comprises a drill string, a bit coupled to the drill string, a drilling motor within the drill string and driving the bit, and a pair of eccentric reamers coupled to the drill string and positioned between the bit and the motor.

Description

REFERENCE TO RELATED APPLICATIONS[0001]This application is a continuation-in-part of U.S. non-provisional application Ser. No. 14 / 298,484, filed Jun. 6, 2014, entitled “METHOD AND APPARATUS FOR REAMING WELL BORE SURFACES NEARER THE CENTER OF DRIFT, which is a continuation of U.S. non-provisional application Ser. No. 13 / 442,316, filed Apr. 9, 2012, entitled “METHOD AND APPARATUS FOR REAMING WELL BORE SURFACES NEARER THE CENTER OF DRIFT,” which claims priority to U.S. provisional application Ser. No. 61 / 473,587, filed Apr. 8, 2011, entitled “METHOD AND APPARATUS FOR REAMING WELL BORE SURFACES NEARER THE CENTER OF DRIFT.” U.S. non-provisional application Ser. No. 14 / 298,484 is also a continuation of U.S. non-provisional application Ser. No. 13 / 517870, filed Jun. 14, 2012, entitled “METHOD AND APPARATUS FOR REAMING WELL BORE SURFACES NEARER THE CENTER OF DRIFT,” which is a continuation of U.S. non-provisional application Ser. No. 13 / 441230, filed Apr. 6, 2012, entitled “METHOD AND APPAR...

AI Technical Summary

Benefits of technology

The present invention provides new tools and methods for drilling well bores. One embodiment is a steerable well bore drilling device, which includes a drill string, a bit, a drilling motor, and a pair of eccentric reamers positioned between the bit and the motor. The eccentric reamers have multiple sets of cutting elements arranged along a spiral path, and they provide a steering force when the drill string is sliding and condition the well bore when it is rotating. The device can be controlled to steer the drill string using a measure while drilling device. The method involves drilling the well bore, steering it by sliding the drill string, and reaming it by rotating the drill string. The eccentric reamers are positioned at a predetermined separation and extend from the drill string a predetermined distance. The method further involves separating the eccentric reamers along the drill string at a predetermined distance corresponding to a curvature of the well bore. The technical effects include improved well bore trajectory, reduced well bore deviation, and improved well bore quality.

Problems solved by technology

Repeated correcting of the direction of the well bore causes micro-ledging and “doglegs,” inducing friction and drag between the well bore and the bottom hole assembly and drill string.

This undesired friction causes several negatives on the drilling process, including but not limited to: increasing torque and drag, ineffective weighting on bit transfer, eccentric wearing on the drill string and bottom hole assembly (BHA), increasing the number of days to drill the well, drill string failures, limiting the distance the well bore can be extended, and issues related to inserting the production string into the well bore.

Such additional reaming runs add considerable expense and time to completion of the well.

Moreover, conventional reaming techniques frequently do not improve the well bore, but instead simply enlarge certain areas of the well bore.

Additionally, one of the problems in steerable drilling is that the elbow of current bent-motors moves around impacting the well bore when drilling straight.

These vibrations negatively impact the drill bit and various electronic sensors in the BHA.

Rotational vibrations also come from the bit due to stick-slip behavior.

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