Subsurface Parameter Realization via Stratigraphic Segmentation
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Solution Overview
Problem
Current methods for estimating subsurface parameters, such as horizontal stress, are computationally challenging to apply meaningfully in models due to uncertainty, particularly in hydraulic fracturing models.
Innovation Solution
The method involves dividing the subsurface parameter profile into stratigraphic units and layers, determining parameter value ranges, selecting layer parameter values, and generating parameter realizations by assigning these values to specific depth ranges, while enforcing predetermined trends to facilitate accurate modeling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If standard statistical methodologies are used to estimate uncertainty for subsurface parameters, then probability distributions can be generated, but the computational application of this uncertainty becomes challenging and difficult to utilize meaningfully in models
Solution Approach 1:
The method segments the continuous subsurface parameter profile into discrete stratigraphic units and further into stratigraphic unit layers. Each layer is assigned a constant parameter value selected from a probability distribution, transforming a continuous uncertainty representation into a discrete, computationally tractable form that can be directly applied in hydraulic fracturing models.
Solution Approach 2:
The method changes the parameter representation from continuous probability distributions to discrete parameter values assigned to specific depth intervals. By selecting parameter values from the probability distribution and assigning them to stratigraphic layers, the uncertainty is preserved in a form that is computationally efficient for modeling applications.
2Reliability
If continuous probability distributions are used to represent subsurface parameters, then uncertainty is captured, but the parameters become difficult to apply as inputs to hydraulic fracturing models
Solution Approach 1:
The continuous subsurface parameter profile is divided into discrete stratigraphic units and further segmented into layers. Each layer is assigned a constant parameter value, converting the continuous distribution into a discrete representation that is directly applicable to hydraulic fracturing models while preserving uncertainty through the statistical selection process.
Solution Approach 2:
The method creates a discrete copy of the continuous probability distribution by selecting parameter values from the distribution and assigning them to stratigraphic layers. This copied discrete representation maintains the statistical characteristics of the original continuous distribution while being computationally compatible with modeling software.
3Productivity
If subsurface parameter profiles are divided into multiple stratigraphic units and layers, then parameter realizations can be generated efficiently, but the process complexity increases
Solution Approach 1:
The method divides the subsurface parameter profile into stratigraphic units and further into layers, creating a hierarchical structure that enables efficient parameter realization generation. Each layer is independently assigned a parameter value from the probability distribution, allowing parallel processing and reducing overall computational complexity despite the increased number of discrete elements.
Solution Approach 2:
The method applies different parameter values to different stratigraphic layers based on local conditions. By selecting parameter values from the probability distribution for each layer independently, the method captures local variability while maintaining a systematic overall structure, improving efficiency through localized parameter assignment rather than uniform treatment.
Data Source
AI summary
Methods of generating a parameter realization, for a subsurface parameter, as a function of depth within a subsurface region are disclosed herein. The methods include dividing a subsurface parameter profile for the subsurface region into a plurality of adjacent stratigraphic units. The methods also include splitting each stratigraphic unit of the plurality of adjacent stratigraphic units into a plurality of stratigraphic unit layers. The methods further include determining a layer parameter value range for each stratigraphic unit layer of the plurality of stratigraphic unit layers and for each stratigraphic unit. The methods also include, within each stratigraphic unit layer, selecting a corresponding layer parameter value from within the layer parameter value range. The methods further include generating the parameter realization by assigning the corresponding layer parameter value to the parameter realization for a corresponding layer depth range of each stratigraphic unit layer.