Intelligent Coring System Downhole Core Retrieval
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Solution Overview
Problem
Current methods for coring subterrain formations face challenges such as time-consuming and costly processes, risk of wellbore deterioration, loss of core integrity during transport, and incomplete data collection due to delayed analysis of drill cuttings and MWD sensor lag, leading to missed intervals and compromised core quality.
Innovation Solution
A method and apparatus for cutting and encapsulating cores downhole using a core barrel with a hollow core bit, encapsulating the core with a pressure-tight material, and employing downhole sensors to measure and transmit formation characteristics for real-time decision-making, allowing for selective core retrieval and continuous drilling without tripping the assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the coring assembly is tripped out of the wellbore to retrieve the core, then the core can be analyzed at surface, but the process becomes time-consuming and increases the risk of wellbore deterioration
Solution Approach 1:
A wireline retrieval system acts as an intermediary to retrieve the core barrel from the wellbore without requiring tripping of the entire coring assembly. The core barrel is engaged by a catch mechanism on the wireline and pulled to surface independently, eliminating the time-consuming roundtrip while maintaining core analysis capability
Solution Approach 2:
The coring system is segmented into independent components: the coring assembly remains in the wellbore for continuous drilling, while the core barrel can be independently retrieved via wireline. This segmentation allows core retrieval without interrupting the drilling operation, reducing time loss and wellbore deterioration risk
2Measurement precision
If the core is transported to surface for analysis, then the core can be examined, but the core loses downhole pressure and temperature causing gases and liquids to bleed out
Solution Approach 1:
The core barrel incorporates a pressure-controlled release mechanism that maintains downhole pressure conditions during retrieval and transport. The core is kept in a pressurized state (preventing fluid bleed-out) until analysis is required, at which point pressure is controlledly released to allow examination of core composition and fluids
Solution Approach 2:
A pressure-maintaining retrieval system acts as an intermediary between the high-pressure downhole environment and the low-pressure surface environment. The wireline retrieval system preserves downhole pressure conditions during transport, preventing gas and liquid bleed-out from the core until controlled release at the analysis stage
3Measurement precision
If MWD sensors are placed behind the drill bit to measure formation properties, then formation characteristics can be measured, but the sensors miss the uppermost part of the formation that is wanted to be cored
Solution Approach 1:
The system performs preliminary coring of the uppermost formation section before the MWD sensors reach that depth. By coring first and then allowing sensors to measure the cored section during retrieval or while passing through, the system captures formation data from intervals that would otherwise be missed by sensors positioned behind the drill bit
4Productivity
If a wireline catch mechanism is used to retrieve the core barrel, then the coring assembly doesn't need to be tripped out, but the core assembly may get stuck and the wireline may break
Solution Approach 1:
The wireline retrieval system incorporates beforehand cushioning measures including a gradual engagement mechanism that reduces impact forces when the catch mechanism engages the core barrel, and a controlled retrieval speed that prevents sudden jerks. These preventive measures reduce the risk of the core assembly getting stuck or the wireline breaking during retrieval operations
Data Source
AI summary
A technology is described of a system capable of altering between extracting a core sample from, or drilling of, a downhole subterrain formation. In coring mode the core is encapsulated downhole at in-situ conditions with a material capable of providing a pressure tight seal around the core, protecting the core and temporary storing the core downhole in an inner string for later retrieval. In drilling mode the unwanted sections of the core is grinded away and the material discarded. No tripping to surface is required to change the composition of the drillstring to alter between drilling mode and coring mode. Downhole sensor technology and intelligence is used to distinguish between areas of interest where the core is encapsulated and kept, and areas of no interest where the core is discarded.