Directional Casing-While-Drilling Rotary Steerable System
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Solution Overview
Problem
Current directional drilling technologies face challenges in efficiently steering drill bits during subterranean operations, particularly in casing while drilling, as they often require rotating the entire drill string, which can lead to inefficiencies and increased wear on drilling equipment.
Innovation Solution
The implementation of a rotary steerable system (RSS) within the casing string, where the RSS is coupled to the drill bit and under-reamer, allowing for radial deviation of the drill bit without rotating the lower section of the casing string, utilizing a swivel to decouple rotational forces and enable precise directional control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the entire drill string is rotated to steer the drill bit, then directional control is achieved, but wear on drilling equipment increases and drilling efficiency decreases
Solution Approach 1:
The drill string is divided into an upper rotatable section and a lower non-rotatable section. The upper section can be rotated to change the orientation of the drill bit, while the lower section remains stationary to reduce wear. This segmentation allows directional control without rotating the entire drill string, resolving the contradiction between directional precision and equipment reliability.
Solution Approach 2:
The system transitions from a static entire-drill-string rotation to a dynamic selective rotation of only the upper section. The ability to independently control rotation of different segments allows the system to achieve directional changes while minimizing wear on the lower section, thereby improving both directional control and equipment lifespan.
2Measurement precision
If the entire drill string is rotated for directional steering, then the drill bit can be steered, but drilling productivity is reduced
Solution Approach 1:
By segmenting the drill string into rotatable and non-rotatable sections, the system enables directional steering through rotation of only the upper section. This reduces the time and energy required for steering operations, thereby maintaining drilling productivity while achieving accurate directional control.
Solution Approach 2:
Instead of rotating the entire drill string (excessive action), the system rotates only the necessary upper section (partial action) to achieve directional steering. This partial rotation reduces operational time and maintains higher drilling productivity while still achieving the required steering accuracy.
3Ease of operation
If the drill bit is coupled directly to the lower section of the casing string, then rotation can be imparted, but spiral patterns are created and precision is lost
Solution Approach 1:
The system introduces an intermediate upper section between the rotation source and the drill bit. This segmentation allows the upper section to rotate without causing the lower section to rotate, thereby preventing spiral patterns and maintaining drilling path accuracy while still enabling rotation transmission to the drill bit.
Solution Approach 2:
The upper section acts as an intermediary between the rotation source and the drill bit. It transmits rotation to the drill bit while isolating the lower section from rotational forces, thus preventing spiral patterns and maintaining precision. The intermediary section resolves the contradiction between ease of rotation transmission and drilling accuracy.
Data Source
AI summary
A directional casing-while-drilling system includes a rotary steerable system disposed within a casing string used as a drill string during casing-while-drilling operations. The casing string of some embodiments may include an upper section and a lower section coupled by a swivel, which may enable the upper section of the casing string to be rotated without substantially rotating the lower section. The rotary steerable system may be disposed at least partially within the lower section of the casing string, and coupled to a drill bit and/or under-reamer. The rotary steerable system may enable radial diversion of the drill bit and/or under-reamer, for example by actuation of one or more components in the rotary steerable system.