Mudweight Window Calculation for Fractured Shale Stability
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Solution Overview
Problem
Current methods for determining mudweight in hydrocarbon reservoirs fail to account for the combined effects of natural fractures and chemical and electrokinetical activity in shale formations, leading to wellbore instability issues such as fluid lost circulation, wellbore collapse, and wellbore enlargement.
Innovation Solution
A computer-implemented method and system using a dual-porosity dual-permeability porochemoelectroelastic approach that considers the porosity, permeability of both rock matrix and natural fractures, and the Hoek-Brown failure criterion to compute safe mudweight windows, integrated into drilling geomechanics software or as a stand-alone wellbore stability analyzer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional mudweight determination methods are used, then the calculation process is simple, but wellbore instability occurs due to not accounting for natural fractures and chemical/electrokinetical activity
Solution Approach 1:
The patent applies a composite theoretical model that integrates dual-porosity (rock matrix and fractures), dual-permeability, poroelasticity, chemomechanics, and electrokinetics. This composite approach combines multiple physical mechanisms into a unified calculation framework, enabling accurate prediction of wellbore stability in complex fractured shale formations while accounting for chemical and electrokinetical effects that conventional single-mechanism models miss.
Solution Approach 2:
The patent transforms the mudweight determination from a simple pressure balance calculation to a multi-parameter analysis involving porosity, permeability, pore pressure, effective stress, chemical potentials, and electrokinetical coefficients. By changing the parameters considered in the calculation, the model captures the complex interactions in fractured formations, resolving the contradiction between computational simplicity and prediction accuracy.
2Measurement precision
If a comprehensive model accounting for all factors is used, then wellbore stability prediction accuracy improves, but computational complexity and data requirements increase
Solution Approach 1:
The patent performs preliminary characterization of the fractured formation by determining dual-porosity and dual-permeability parameters before drilling operations. By pre-establishing the geomechanical and hydraulic properties of both the rock matrix and fracture networks, the model reduces the need for complex real-time measurements during drilling, as the critical parameters are determined in advance through formation evaluation techniques.
Solution Approach 2:
The patent introduces an intermediary computational framework that integrates multiple physical mechanisms (poroelasticity, chemomechanics, electrokinetics) into a unified mudweight calculation model. This intermediary model acts as a bridge between complex formation characteristics and practical drilling parameters, translating complex multi-physics interactions into actionable mudweight recommendations without requiring direct measurement of all underlying mechanisms.
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 effectively determines a safe mudweight window that maintains wellbore stability by accounting for the complex interactions in naturally fractured shale formations, preventing wellbore collapse and fracturing, and ensuring stable drilling operations.
Implementation Method 1
determining, by the hardware processor, Hoek-Brown failure criterion data
Data Source
AI summary
The present disclosure describes methods and systems, including computer-implemented methods, computer program products, and computer systems, for determining a mudweight of drilling fluids in a hydrocarbon reservoir. One computer-implemented method includes: receiving pore pressure data of a rock formation in the hydrocarbon reservoir; determining permeability data of fractures of the hydrocarbon reservoir; determining Hoek-Brown failure criterion data; and determining a safe mudweight window based on the pore pressure data of the rock formation, the permeability data of the fractures, and the Hoek-Brown failure criterion data.