Downhole Rock Characterization With In Situ Strength Testing
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Solution Overview
Problem
Conventional core sampling methods for rock mechanics characterization in oil wells result in sample damage, alteration of the original tensional state, increased non-productive time, and safety risks due to manual handling and transportation of core samples, especially when laboratories are distant.
Innovation Solution
A downhole rock characterization tool with integrated surface preparation and testing cutters that perform measurements in situ, allowing for unconfined compressive strength and internal friction angle tests without removing samples to the surface, using a single drill bit with interchangeable blunt and sharp cutters to clear debris and perform tests.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If core samples are removed from the formation and transported to the surface for analysis, then sample analysis can be performed, but the sample's original tensional state is altered and samples are damaged or excessively fractured
Solution Approach 1:
The invention extracts the testing function from the surface laboratory environment and places it downhole at the formation site. The testing tool performs rock mechanics tests directly on the formation in situ, eliminating the need to extract and transport core samples while preserving the original stress state and sample integrity.
Solution Approach 2:
The invention introduces a downhole testing tool as an intermediary device that enables rock mechanics characterization directly within the wellbore. This intermediary system includes testing cutters, force sensors, and torque sensors that work together to perform tests on the formation without requiring sample removal.
2Measurement precision
If core samples are transported to distant laboratories for testing, then comprehensive analysis can be performed, but time and costs increase significantly
Solution Approach 1:
The invention enables the formation to be tested in situ using the downhole testing tool, eliminating the need for external laboratory services. The tool performs all necessary rock mechanics tests directly at the formation site, making the system self-sufficient and eliminating transportation time and associated costs.
3Measurement precision
If manual handling and transportation of core samples is performed, then samples can be retrieved for analysis, but safety risks increase due to manual labor requirements
Solution Approach 1:
The invention replaces the mechanical system of manual core sample handling and transportation with an automated downhole testing system. The testing tool performs all operations mechanically within the wellbore, eliminating the need for human operators to handle core samples manually and thereby removing the associated safety risks.
4Measurement precision
If conventional coring operations are performed with multiple drill strings, then core samples can be obtained, but non-productive time increases due to making and breaking drill strings
Solution Approach 1:
The invention creates a multi-functional downhole tool that combines the capabilities of core sampling, debris removal, and rock mechanics testing in a single device. This universal tool can perform multiple functions without requiring changes to the drill string configuration, thereby eliminating non-productive time associated with making and breaking drill strings.
Data Source
AI summary
The present disclosure relates to the drilling of oil wells and more particularly to a testing tool, a testing assembly and method for use in measuring selected rock mechanics characteristics downhole.