Reservoir Property Estimation via Temperature Cross-Correlation
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Solution Overview
Problem
Conventional methods for determining reservoir properties, such as hydraulic diffusivity, require invasive and difficult-to-analyze tests or measure proxies that are not directly related to flow properties, making them inefficient and costly.
Innovation Solution
The implementation of a system that uses long-term temperature monitoring from sensors in subsurface boreholes to determine hydraulic diffusivity by correlating ambient temperature fluctuations, allowing for passive estimation of reservoir properties without manipulating the reservoir, thereby providing accurate and efficient estimates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional invasive tests are used to determine reservoir properties, then measurement precision may be improved, but device complexity and ease of operation deteriorate due to invasive procedures and difficult analysis
Solution Approach 1:
The patent replaces invasive mechanical testing procedures with passive thermal sensing. Instead of injecting fluids or applying mechanical stress to measure reservoir properties, the system uses temperature sensors to detect natural temperature fluctuations and derives hydraulic diffusivity from these passive measurements, eliminating the need for complex invasive test equipment and procedures
Solution Approach 2:
The system utilizes naturally occurring temperature fluctuations in the reservoir as the measurement signal source. The reservoir's own thermal behavior serves as the test input, eliminating the need for external energy input or active testing equipment. The ambient thermal noise becomes the probing signal that reveals reservoir properties
2Measurement precision
If conventional invasive tests are used to determine reservoir properties, then measurement precision may be improved, but productivity deteriorates due to difficult analysis and time-consuming procedures
Solution Approach 1:
The patent replaces complex mechanical testing and analysis procedures with automated thermal data processing. The system automatically computes cross-correlations of temperature signals and derives hydraulic diffusivity through computational algorithms, eliminating the need for manual analysis of complex test data and significantly improving determination efficiency
Solution Approach 2:
The system performs preliminary data processing by continuously recording temperature fluctuations and pre-computing cross-correlations. This preparatory work is done in advance so that when reservoir property determination is needed, the analysis can be quickly completed using pre-processed data, improving overall productivity
3Measurement precision
If conventional tests are used to measure reservoir properties, then measurement precision may be improved, but ease of operation deteriorates due to difficult-to-analyze data
Solution Approach 1:
The patent replaces difficult-to-analyze pressure or flow data with temperature fluctuation data that follows simpler thermal diffusion equations. The temperature signals naturally encode reservoir properties through thermal conduction and advection, making the data inherently easier to interpret through straightforward cross-correlation analysis compared to conventional pressure transient analysis
4Ease of operation
If passive temperature monitoring is used to determine reservoir properties, then ease of operation and productivity are improved, but measurement precision may deteriorate compared to invasive tests
Solution Approach 1:
The patent uses temperature as an intermediary parameter that indirectly measures hydraulic properties. Temperature fluctuations act as a mediator that translates fluid flow and pressure information into thermal signals that can be easily measured and analyzed, maintaining measurement precision while improving ease of operation
Solution Approach 2:
The system changes the measurement parameter from pressure or flow rate to temperature. This parameter transformation allows passive measurement while maintaining precision because temperature diffusion is directly coupled to fluid flow through the heat advection term in the thermal diffusion equation, providing an accurate proxy for hydraulic diffusivity
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 enables non-invasive, cost-effective determination of hydraulic diffusivity and other reservoir properties, overcoming the limitations of traditional methods by utilizing ambient noise in temperature data to infer hydrogeological properties, thus facilitating precise characterization of fluid flow and pressure migration.
Implementation Method 1
long-term temperature data obtained from sensors in subsurface boreholes
Implementation Method 2
the ambient temperature fluctuations record flow fluctuations
Implementation Method 3
compute a cross-correlation of their corresponding time-series temperature data, to compute a time derivative of the cross-correlation
Data Source
AI summary
An apparatus comprises at least one processing device comprising a processor coupled to a memory. The processing device is configured to obtain time-series temperature data from respective temperature sensors arranged at respective different subsurface depths, and for each of a plurality of pairs of the temperature sensors, to compute a cross-correlation of their corresponding time-series temperature data, to compute a time derivative of the cross-correlation, and to generate an estimate of at least one reservoir property based at least in part on the time derivative of the cross-correlation. At least one automated action is performed based at least in part on the generated estimate, such as, for example, controlling an amount of fluid flow into or out of a particular subsurface region. The generated estimates illustratively comprise estimates of subsurface hydraulic diffusivity.