Casing Bit Hollow Crown Segmented Blades Drill-Out
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Solution Overview
Problem
Conventional drilling and casing operations are time-consuming and costly due to the need for sequential drilling and retrieval of drill strings, and subsequent drilling through cemented casing bits can damage drill bits and casing due to the robust nature of these bits.
Innovation Solution
Development of earth-boring tools with a bit crown comprising a hollow body, radially extending blades, and polycrystalline diamond compact cutting elements, along with a structural inlay of composite material, designed to be more easily drilled through by subsequent drill bits, reducing the volume of hard-to-drill material and potential damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a robust drill bit is used to drill through cemented casing, then the drill bit can penetrate the casing, but the drill bit and casing may be damaged due to the robust nature of the bit
Solution Approach 1:
The bit crown is segmented into multiple blades rather than being a single solid structure. This segmentation reduces the overall volume of hard material that subsequent drill bits must penetrate, while each blade remains sufficiently robust to perform its drilling function. The blades are arranged radially to distribute the drilling load and reduce concentrated stress points that could cause damage.
Solution Approach 2:
Different regions of the bit crown have different material properties and structural characteristics. The blades contain cutting elements for effective rock cutting, while the spaces between blades and the hollow body structure reduce overall hardness and volume in regions that will be drilled through later. This local differentiation allows the bit to be robust where needed for drilling while being easier to penetrate where subsequent drilling occurs.
2Reliability
If sequential drilling and casing operations are performed, then proper well construction is achieved, but the process is time-consuming and costly due to retrieval procedures
Solution Approach 1:
The invention merges the drilling and casing operations into a single integrated process by attaching the bit crown directly to the casing string. This eliminates the need for separate drill string retrieval and casing installation steps, as the bit crown remains attached to the casing throughout the drilling and cementing process, enabling continuous operation without time-consuming interruptions.
Solution Approach 2:
The bit crown serves multiple functions: it drills the borehole, guides the casing into place, and remains attached during cementing operations. This multi-functionality eliminates the need for separate drill bits and drill strings, allowing the same structure to perform drilling, casing placement, and cementing support functions in sequence without retrieval or replacement.
3Productivity
If further drilling is required after cementing, then additional borehole depth or lateral drilling is achieved, but drilling through the robust casing bit is difficult and time-consuming
Solution Approach 1:
The design extracts or removes material from the bit crown structure by creating a hollow body with radial blades rather than using a solid robust bit. This extraction of material reduces the volume and mass of hard material that must be removed during subsequent drilling operations, making drill-out operations faster and less complex while still maintaining sufficient structural integrity for the original drilling function.
Data Source
AI summary
Casing bits include a bit crown having a substantially hollow interior. The bit crown has blades over a face portion thereof, the blades including a plurality of cutting elements attached thereto. The bit crown further includes a composite inlay positioned at least within the substantially hollow interior. The casing bits also include case hardened outer surfaces radially outside a drill-out region. The casing bits further include short-substrate cutting elements. Methods of forming a casing bit are also disclosed.