Hexagonal Sandstone Compaction Model for Porosity Accuracy
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Solution Overview
Problem
Existing compaction models in reservoir characterization overestimate chemical compaction, leading to unrealistically low porosity estimates, as they simplify grain packing using cubic closed-packed arrangements, failing to accurately represent real-world compaction trends.
Innovation Solution
A method that models compaction using a hexagonal closed-packed arrangement of rock grains, incorporating both mechanical and chemical compaction profiles based on vertical burial depth, effective stress, and geological time, providing a more accurate estimation of porosity changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If cubic closed-packed arrangement is used to model grain packing, then calculation simplicity is improved, but porosity estimation accuracy deteriorates
Solution Approach 1:
The patent changes the geometric parameters of the grain packing model from cubic arrangement to hexagonal closed-packed arrangement. This parameter change maintains calculation feasibility while significantly improving porosity estimation accuracy, as hexagonal packing better represents natural sedimentary rock grain arrangements and yields more realistic porosity values that align with well logging observations.
2Device complexity
If cubic closed-packed arrangement is used for chemical compaction modeling, then model simplicity is improved, but compaction trend accuracy deteriorates
Solution Approach 1:
The patent modifies the structural parameters of the compaction model by adopting hexagonal closed-packed grain arrangement instead of cubic arrangement. This change preserves the mathematical tractability of the model while dramatically improving its reliability in predicting actual compaction trends observed in reservoirs, as the hexagonal geometry better captures the physical reality of grain packing under burial stress.
3Productivity
If simplified cubic packing model is used, then computational efficiency is improved, but final porosity realism deteriorates
Solution Approach 1:
The patent changes the geometric configuration parameter from cubic to hexagonal closed-packed arrangement. This modification maintains computational efficiency since both models use regular geometric patterns amenable to mathematical modeling, while the hexagonal arrangement produces more realistic final porosity values that match field observations from well logging data.
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 results in a more realistic compaction model that aligns with observed data, accurately capturing both mechanical and chemical compaction effects, thereby improving hydrocarbon production operations by providing a more precise porosity trend with depth.
Implementation Method 1
Physical compaction, also termed mechanical compaction, mainly involves grain reorientation and repacking accompanied by water expulsion from porous sediments
Implementation Method 2
Chemical compaction, sometimes termed pressure solution, in sandstones mainly refers to grain dissolution, diffusion, and precipitation at the grain-to-grain contacts
Implementation Method 3
Chemical compaction, sometimes termed pressure solution, in sandstones mainly refers to grain dissolution, diffusion, and precipitation at the grain-to-grain contacts
Data Source
AI summary
A method for modeling compaction in a reservoir including obtaining a profile of vertical burial depth, a profile of effective stress against the vertical burial depth, and approximating a plurality of rock grains with a hexagonal closed-packed arrangement of spheres to estimate compacted mechanical and chemical porosity profiles.