Coring Bit Face Discharge Channel Design
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Solution Overview
Problem
Conventional core barrel assemblies face issues with core sample damage due to excessive drilling fluid invasion and contamination, leading to unreliable formation data, and are prone to leaving core stumps in the well bore, which interfere with operations.
Innovation Solution
The design includes a core barrel assembly with a tubular body and bit body that manage fluid flow by increasing hydraulic losses in the throat discharge channel, reducing the Total Flow Area (TFA) and optimizing the location of face discharge channels to minimize drilling fluid contact with the core, using a bit body material like maraging steel or enhanced metal matrix bits with embedded hard particles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If drilling fluid is circulated through the throat discharge channel to cool and lubricate cutters, then cutter performance is improved, but drilling fluid invades and contaminates the core sample
Solution Approach 1:
A flow diverter is introduced as an intermediary component between the throat discharge channel and the core sample. This flow diverter redirects drilling fluid flow away from the core sample while still allowing the fluid to reach the cutters for cooling and lubrication, thus mediating between the conflicting requirements of cutter performance and core protection
Solution Approach 2:
The throat discharge channel is segmented into multiple flow paths: one path directs fluid to the cutters for cooling and lubrication, while another path directs fluid away from the core sample. This segmentation allows the system to simultaneously achieve cutter performance and prevent core contamination
2Productivity
If the core shoe is positioned to receive the core at the throat, then core recovery is improved, but core stumps are left in the well bore
Solution Approach 1:
The core shoe is designed with extended length and positioned to make preliminary contact with the core at the throat area. This preliminary action allows the core shoe to gradually engage and pull the core through the throat, preventing the formation of core stumps and ensuring complete core recovery
Solution Approach 2:
The core shoe has an asymmetric geometry with different diameters at different locations. The larger diameter at the throat area provides enhanced engagement with the core, while the tapered section facilitates smooth core passage, creating an asymmetric flow path that prevents core stump formation
3Temperature
If the narrow annulus between core bit and core shoe is used for fluid flow, then cooling is provided, but fluid velocity increases causing erosion and contamination
Solution Approach 1:
The fluid flow path is extended in the longitudinal dimension by increasing the throat discharge channel length. This dimensional change allows the fluid to travel a longer distance, increasing exposure to cutters for cooling while reducing velocity and erosive effects before reaching the core sample
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 core stump length and exposure to drilling fluid, improving core quality and recoverability while providing more reliable formation characterization by minimizing fluid invasion and contamination.
Implementation Method 1
a core bit having features to control flow of drilling fluid into a narrow annulus between the core bit inside diameter and the outside diameter of an associated core shoe
Implementation Method 2
application of weight to the core bit through the outer barrel and drill string in conjunction with rotation of these components
Implementation Method 3
a drilling fluid is usually circulated through the core barrel assembly to lubricate and cool the plurality of cutters disposed on the face surface of the core bit
Implementation Method 4
remove formation cuttings from the bit face surface to be transported upwardly to the surface through the annulus defined between the drill string and the wall of the well bore
Implementation Method 5
a core bit adapted to cut the cylindrical core and to receive the core in a central opening, or throat
Implementation Method 6
The core shoe is configured to receive the core as it enters the throat and to guide the core into the inner tube
Data Source
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AI summary
A coring bit for extracting a sample of subterranean formation material from a well bore may include a bit body having a bit face and an inner surface defining a substantially cylindrical cavity of the bit body. A first portion of the inner surface may be configured to surround a core catcher. The coring bit may include a face discharge channel inlet formed in the inner surface of the bit body longitudinally at or above the first portion of the inner surface. The coring bit may also include a face discharge channel extending through the bit body from the face discharge channel inlet to the bit face. A tubular body having a core catcher may be disposed in the coring bit to form a coring tool. Methods of forming such bit bodies may include forming an inlet for a face discharge channel in the inner surface of the bit body at a location longitudinally at or above the first portion of the inner surface and forming a face discharge channel extending from the inlet to the bit face.