Karst Cave Location Determination in Geological Models
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Solution Overview
Problem
Current methods for modeling karstification in geological models, particularly island karstification, fail to accurately represent the formation and impact of caves, which are crucial for estimating hydrocarbon resources and understanding karstic zones in island and coastal areas.
Innovation Solution
A method for determining the location and characteristics of karstified caves in a geological model using a three-dimensional mesh model, where the presence of caves is represented by binary variables, and their size and number are determined based on distribution functions and distance values, with the option to account for cave collapse by multiplying the proportion of caves by a factor, and integrating permeability calculations through statistical approaches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If usual karstic simulation tools are used, then the simulation process is simple, but the accuracy of modeling island karstification is insufficient
Solution Approach 1:
The method segments the karstification modeling process into distinct computational stages: defining karstic zones based on geological criteria, generating cave networks using stochastic processes, calculating collapse volumes separately, and integrating results into the geological model. This segmentation allows each aspect to be handled with appropriate algorithms while maintaining overall model accuracy for island karstification.
Solution Approach 2:
The invention introduces specific parameters for island karstification including salt wedge position, aquifer beat characteristics, and dissolution rates that vary with depth and proximity to salt water. These parameter changes enable accurate representation of the unique chemical and physical conditions in island and coastal karst environments that standard tools cannot capture.
2Reliability
If the proportion of cellars is increased to account for collapse, then the representation of collapsed volume is improved, but the model complexity increases
Solution Approach 1:
The method performs preliminary identification of potential collapse zones based on cellar proximity to salt water and depth criteria before calculating actual collapse volumes. By pre-defining which areas are susceptible to collapse and applying multiplication factors only to those zones, the model accurately represents collapse phenomena without requiring complex real-time calculations throughout the entire model.
Solution Approach 2:
The invention applies different collapse multiplication factors (3-5 times) locally to cells containing cellars versus cells without cellars, and further differentiates between cells near salt water interfaces and deeper cells. This local differentiation allows accurate representation of collapse variability in different geological contexts while maintaining computational efficiency.
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 method enables accurate and effective modeling of cave formation and permeability in karstic zones, improving the estimation of hydrocarbon resources and understanding of karstification phenomena in island and coastal areas, by accounting for the specific geological features and processes involved.
Implementation Method 1
the phenomenon by which a rock is shaped by dissolving carbonates, for example, in water. Water infiltrates through interstices in the rock, such as pores or fractures. This infiltration increases the size of these interstices due to the dissolution of carbonates from the rock in the infiltrated water.
Data Source
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AI summary
The present invention concerns a method for determining a location of karst caves (503, 504) in a geological model (100, 601), the method comprising, for each current point (109, 108, 107) of a set of points of a closed space of the model, determining (606) a distance value; receiving an average value (608); and, for each current point of said set of points of the closed space, determining (607) a presence of caves for said current point, said determination of the presence of caves depending at least on the received average value and on the distance value determined for said current point. A collapse procedure can also be implemented as described in the description.