Concentric Drill String for Heavy Oil Reservoirs
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Solution Overview
Problem
Conventional drilling methods for heavy oil and bitumen in carbonate and sandstone reservoirs face issues such as formation damage, lost circulation, and increased drilling time and cost due to the need to remove the drill string after drilling, which can lead to formation damage and impaired well completion.
Innovation Solution
The use of concentric or single wall drill strings equipped with induction heaters that remain in the well after drilling, allowing for in-situ heating and stimulation of heavy oil or bitumen, reducing the risk of lost circulation and enabling easier hole cleaning by delivering drilling fluids and chemicals through the annulus, and converting into a production string for efficient oil or bitumen extraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional single wall drill string is used for drilling heavy oil wells, then drilling operations can be performed, but formation damage and lost circulation problems occur
Solution Approach 1:
The drill string is segmented into two concentric tubes (inner and outer tubes) that can function independently or together. The outer tube handles drilling fluid circulation while the inner tube provides structural support and can serve as a production conduit, allowing separate optimization of drilling and production functions to avoid formation damage
Solution Approach 2:
The concentric drill string serves multiple functions simultaneously: the outer tube acts as a drilling conduit and circulation path, the inner tube provides structural support and can function as a production string, and together they enable hole cleaning and stimulation operations without requiring separate equipment or drill string removal
2Ease of operation
If drill string is removed after drilling to complete the well, then well completion can proceed, but lost circulation and formation damage increase
Solution Approach 1:
The concentric drill string is designed to remain in the well and transition from a drilling tool to a production string. The inner tube serves as the production conduit while the outer tube can be cemented in place to form a permanent liner, eliminating the need to remove the drill string and avoiding associated formation damage and lost circulation risks
Solution Approach 2:
The drill string is designed and installed with the understanding that it will remain in place for production. Slots are temporarily sealed during drilling, then opened through heating or mechanical means after drilling completion, allowing the same structure to serve both drilling and production functions without removal
3Productivity
If conventional drilling methods are used for heavy oil reservoirs, then drilling can be performed, but additional stimulation time and cost are required
Solution Approach 1:
The drilling and stimulation functions are merged into a single operation. Induction heaters are integrated onto the concentric drill string, allowing thermal stimulation to be applied immediately after drilling without removing the drill string or requiring separate stimulation operations, thereby reducing time and cost
Solution Approach 2:
The concentric drill string remains in place continuously from drilling through production. The induction heaters can be activated at any point during or after drilling to provide continuous or intermittent heating, maintaining reservoir temperature and heavy oil flowability without interrupting production operations
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach reduces formation damage, lowers the risk of lost circulation, and facilitates efficient well completion and production by allowing the drill string to act as both a drilling and production tool, enhancing the flow of heavy oil or bitumen while minimizing the need for additional stimulation methods.
Implementation Method 1
a portion of the outer tube of the concentric drill string or the wall of the single wall drill string comprises a plurality of temporarily sealed slots and/or induction heaters and may also be used to stimulate the well
Data Source
AI summary
An apparatus and method for drilling a well in a heavy oil or bitumen reservoir for in situ recovery of heavy oil and bitumen is provided. More particularly, an apparatus and method for drilling, completing and/or stimulating a heavy oil or bitumen well in a heavy oil or bitumen reservoir is provided, comprising: providing a concentric drill string having an inner tube and an outer tube defining an annulus therebetween, the outer tube further having a plurality of slots sealed with a temporary filler material; drilling a borehole into the reservoir using a drilling member connected at the lower end of the concentric drill string and delivering drilling medium through one of the annulus or inner tube and extracting the exhaust drilling medium through the other of the annulus or inner tube; leaving the concentric drill string in the well after drilling of the borehole is completed; and removing the temporary filler material to expose the plurality of slots in the outer tube and form a slotted liner.