Rotary Steerable Tool Housing for Vibration-Resistant Azimuthal Logging

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Solution Overview

Problem

Conventional formation evaluation sensors deployed in drilling operations are susceptible to shock and vibration-related errors and failures, and require uniform drill string rotation for accurate azimuthal logging, limiting their effectiveness in geosteering applications.

Innovation Solution

Deployment of formation evaluation sensors in a rotary steerable tool housing with controlled rotation rate, using blades to eccenter the housing and maintain desired orientations for improved measurement accuracy, enabling both azimuthal and non-azimuthal measurements and simultaneous physical standoff calculations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If FE sensors are deployed in a rotating section of the BHA with the drill string rotation rate, then azimuthal logging measurements can be obtained, but the sensors are subject to high lateral, axial, and torsional vibrations causing shock and vibration related errors and failures

Engineering Contradiction:

Improveazimuthal logging measurement accuracyVSAvoidsensor reliability under vibration

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The system separates the drilling function (rotating drill string) from the measurement function (stationary housing with FE sensors). The housing is decoupled from the drill string rotation, creating an independent measurement platform that is not subjected to drilling vibrations while still enabling azimuthal measurements through controlled rotation of the housing at much lower speeds.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent replaces the conventional mechanical coupling between the drill string and FE sensors with a hydraulic control system. The housing rotation is controlled by hydraulic pressure applied to a piston that interacts with a cam mechanism, allowing precise control of rotation speed and position independent of drill string rotation, thereby eliminating vibration-related measurement errors.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Measurement precision

If conventional FE sensor deployments are used, then sensors can be deployed in the rotating BHA, but uniform drill string rotation rate is required to reduce statistical errors in azimuthally focused logging data

Engineering Contradiction:

Improveazimuthal logging data accuracyVSAvoidcontrol system complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The system transitions from requiring uniform drill string rotation to using a dynamically controlled housing rotation system. The housing can be rotated at variable speeds and held at specific orientations using hydraulic control, allowing the system to adapt to different measurement requirements without requiring uniform rotation throughout the entire drilling process.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent incorporates feedback control through hydraulic pressure sensing and cam mechanism positioning. The system can detect the housing orientation and rotation speed, and adjust the hydraulic pressure accordingly to maintain desired measurement conditions, replacing the need for complex uniform rotation control with a more flexible feedback-based approach.

Inventive Principle:

Principle #23Feedback

3Productivity

If FE sensors are rotationally coupled to the drill string, then the sensors rotate with the drill string during drilling, but the sensors are exposed to high lateral, axial, and torsional vibrations during normal drilling operations

Engineering Contradiction:

Improvedrilling productivityVSAvoidshock and vibration exposure

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent introduces an intermediary hydraulic control system between the drill string and the FE sensors. This intermediary mechanism (hydraulic piston with cam) acts as a buffer and controller, allowing the housing to rotate independently of the drill string at much lower speeds while protecting the sensors from high-vibration exposure during drilling operations.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS7950473B2Non-azimuthal and azimuthal formation evaluation measurement in a slowly rotating housing

Publication Date: 2011.05.31 SCHLUMBERGER TECH CORP

AI summary

A steering tool configured for making azimuthal and non-azimuthal formation evaluation measurements is disclosed. In one embodiment a rotary steerable tool includes at least one formation evaluation sensor deployed in the steering tool housing. The steering tool may include, for example, first and second circumferentially opposed formation evaluation sensors or first, second, and third formation evaluation sensors, each of which is radially offset and circumferentially aligned with a corresponding one of the steering tool blades. The invention further includes methods for geosteering in which a rotation rate of the steering tool housing in the borehole (and therefore the rotation rate of the formation evaluation sensors) is controlled. Steering decisions may be made utilizing the formation evaluation measurements and/or derived borehole images.