In-situ Stress Estimation from Drilling Response Data
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Solution Overview
Problem
Conventional methods for estimating in-situ stresses in the Earth's crust are inadequate in cases where sonic and image data are lacking, particularly in overburden sections, development wells, and unconventional wells due to data scarcity or budgetary constraints, leading to inaccurate stress assessments that can result in uncontrolled fluid escape and inefficient hydrocarbon recovery.
Innovation Solution
A method that estimates principal in-situ stresses using drilling response data, such as weight on bit, rate of penetration, and rotations per minute, which allows for stress estimation in data-scarce intervals by calibrating and validating a drilling response-related stress model using data-rich reservoir intervals, enabling accurate stress estimation independently along the wellbore.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional stress estimation methods using sonic and image logs are used, then measurement precision is improved, but device complexity and data availability requirements increase
Solution Approach 1:
The patent extracts the essential stress estimation function from complex logging operations by using drilling response parameters (WOB, RoP, RPM) that are already collected during routine drilling operations. This eliminates the need for separate sonic and image log acquisitions, reducing device complexity while maintaining stress estimation capability.
Solution Approach 2:
The drilling operation itself generates the data needed for stress estimation through standard drilling parameters. The drilling process serves dual purposes: both cutting rock and providing stress measurement data, eliminating the need for separate measurement devices or operations.
2Measurement precision
If sonic and image logs are acquired for stress estimation, then measurement precision improves, but loss of time and increased cost occur
Solution Approach 1:
The patent merges stress estimation data acquisition with routine drilling operations. By combining these functions, the time required for separate logging operations is eliminated, as stress data is obtained concurrently with drilling activities using existing drilling parameters.
Solution Approach 2:
Stress estimation data is obtained during the drilling process itself, before separate logging operations would be conducted. This preliminary acquisition of stress data during drilling eliminates subsequent time-consuming logging trips and data collection activities.
3Ease of operation
If drilling response parameters are used for stress estimation, then ease of operation and data availability improve, but measurement precision may be compromised
Solution Approach 1:
The patent transforms routine drilling parameters (WOB, RoP, RPM) into stress estimation data through empirical relationships and calibration. By changing the interpretation and application of these parameters from purely operational to diagnostic, measurement precision is improved while maintaining ease of operation.
Solution Approach 2:
The system uses calibration against known stress conditions and iterative refinement of drilling response interpretations to improve measurement precision. Feedback loops allow the system to learn from accumulated data and improve accuracy over time while maintaining operational simplicity.
Data Source
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AI summary
Estimating in-situ stress of an interval having drilling response data is described. Estimating involves obtaining drilling response data of a data rich interval with available data. Estimating relative rock strength as a composite value that includes in-situ stress and rock strength. Estimating a Poisson's ratio from the relative rock strength. Generating a stress model that includes uniaxial strain model using the Poisson's ratio. Verifying the stress model with the available data. Applying the stress models in a non-data rich interval.