Wellbore Stability Prediction via Caliper Log Feedback
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current wellbore stability prediction techniques rely on breakout width or yield zone calculations, which lack direct comparison with actual measurements and are uncertain due to limited image data quality and coverage, leading to inaccurate mud weight determination and increased drilling non-productive time.
Innovation Solution
A methodology that calculates the failure zone around a wellbore by transforming in-situ earth stresses into a local coordinate system, incorporating principal stresses, mud weight, and rock strength to predict the maximum wellbore diameter and calibrate geomechanical models for accurate mud weight prediction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If breakout width or yield zone calculations are used for wellbore stability prediction, then the prediction can be made using available data, but the accuracy is reduced due to lack of direct comparison with actual measurements
Solution Approach 1:
The patent applies feedback by comparing predicted wellbore diameters from geomechanical models with actual caliper log measurements. This comparison provides feedback to validate and calibrate the models, improving both accuracy and reliability of wellbore stability predictions. The caliper logs serve as ground truth data that verifies whether the model predictions match actual wellbore conditions.
Solution Approach 2:
The patent replaces indirect mechanical inference methods (breakout width calculations from image logs) with a more direct approach using caliper log measurements. Instead of inferring stability from breakout morphology, the method directly compares predicted diameters with actual measured diameters, substituting indirect mechanical analysis with direct measurement validation.
2Ease of operation
If breakout width calculations are used, then wellbore stability can be assessed, but the measurement precision is limited due to image data quality and coverage issues
Solution Approach 1:
The patent introduces caliper log measurements as an intermediary validation tool. Instead of relying solely on breakout width calculations from image logs, the method uses caliper logs as an intermediary data source that directly measures wellbore diameter. This intermediary measurement bridges the gap between theoretical predictions and actual wellbore conditions, providing more precise validation.
3Productivity
If currently available prediction techniques are used, then mud weight can be determined, but the reliability is reduced leading to increased drilling non-productive time
Solution Approach 1:
The patent uses caliper log measurements as feedback to validate mud weight predictions. By comparing predicted wellbore diameters with actual measurements, the system can verify whether the determined mud weight is appropriate. This feedback loop increases reliability of mud weight determination, reducing drilling problems and non-productive time.
Data Source
AI summary
Disclosed are methods, systems, and computer-readable medium to perform operations including: determining a state of in-situ earth stresses around a wellbore located in a formation; transforming the in-situ earth stresses from a global Cartesian coordinate system to a local wellbore coordinate system; calculating, based on the transformed in-situ earth stresses in the local wellbore coordinate system, principal stresses around the wellbore; generating, using a failure criterion that incorporates (i) principal stresses, (ii) mud weight, and (iii) rock strength, a function for calculating a rock compressive failure; and predicting, using the function, a failure zone around the wellbore.