Separable Drill Bit for Casing Installation in Blind Horizontal Wells
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Solution Overview
Problem
In directional boring, especially in soft or loose soils, the borehole often collapses before well casing can be installed, as standard practices require removing the drilling string before casing insertion, leading to obstruction and reduced drilling effectiveness.
Innovation Solution
A system and method using a hollow drilling string with a separable drill bit assembly that allows the drill bit to be remotely uncoupled from the string, enabling the well casing to be installed while the drilling string remains in place to support the borehole, and then the string is removed, preventing collapse and facilitating casing installation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the drilling string is removed before casing insertion, then the casing can be installed in the borehole, but the borehole collapses in soft or loose soils
Solution Approach 1:
The drill bit assembly is segmented into a separable configuration where the drill bit can be detached from the drilling string. This allows the drilling string to remain in the borehole to provide support while the drill bit is removed, enabling casing installation without borehole collapse in soft soils.
Solution Approach 2:
The drilling string is left in place to preliminarily support the borehole walls before casing installation. This preliminary support action prevents borehole collapse during the subsequent casing installation process in unstable soil conditions.
2Reliability
If the drilling string remains in place to support the borehole, then the borehole remains open for casing installation, but the drill bit must be remotely uncoupled
Solution Approach 1:
The drill bit is extracted or removed from the drilling string by uncoupling the latch mechanism. This allows the drilling string to remain in the borehole for support while the drill bit is taken out, enabling casing installation without requiring complete string removal.
Solution Approach 2:
The latch mechanism acts as an intermediary coupling device that can be remotely actuated to uncouple the drill bit from the drilling string. This mediator enables the separation of the drill bit while maintaining the drilling string in place for borehole support.
3Ease of manufacture
If standard practice is followed, then the drilling process is simple, but productivity is reduced due to re-drilling needs
Solution Approach 1:
By segmenting the drill bit assembly from the drilling string, the system enables the drilling string to remain in place and support the borehole during casing installation. This eliminates the need to re-drill collapsed boreholes, significantly improving productivity while maintaining process simplicity.
Data Source
AI summary
A system and method for installing casing in a blind horizontal well for blind horizontal directional borings. The system and method may include an example of an offset transmitter sonde assembly that contains an open central passage through which well casing can be inserted, and an example of a drill bit assembly that may be remotely uncoupled from a drill string, leaving the bit in the bore created. Remote uncoupling of the drill bit assembly tends to allow a casing to be installed in the bore while the drill string and bit remain in the bore for support during casing installation. After installation of the casing the drill bit assembly may be uncoupled from the drill string, allowing the drill string to be withdrawn from the bore, with the drill bit assembly remaining in the bore.