Multi-frequency Dielectric Tool for Downhole Wettability Estimation
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Solution Overview
Problem
Conventional methods for determining wettability in formations are time-consuming and often fail to accurately represent downhole conditions, as they do not adequately capture the complex polarization effects and wettability information necessary for effective reservoir management.
Innovation Solution
A multi-frequency dielectric measurement tool is used to estimate wettability by differentiating between bound and free water, incorporating bulk density and matrix permittivity into a modified petrophysical model to provide inversion results that inform reservoir management decisions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If conventional dielectric models are used to interpret measurements, then water saturation and reservoir properties can be estimated, but wettability information is not adequately provided
Solution Approach 1:
The patent segments the dielectric measurement interpretation by separating wettability estimation from standard water saturation calculation. It introduces distinct wettability indices (WI) derived from dielectric dispersion characteristics at different frequencies, allowing independent wettability assessment alongside traditional reservoir property evaluation.
Solution Approach 2:
The patent adds a new dimension to dielectric interpretation by incorporating frequency-dependent dielectric dispersion data. Instead of using single-frequency measurements, it utilizes multi-frequency data to extract additional wettability parameters, transforming the interpretation from two-dimensional (water saturation only) to three-dimensional (water saturation, wettability index, and bound water fraction).
2Measurement precision
If laboratory wettability measurements are performed, then wettability data can be obtained, but the measurements do not fully represent actual downhole wettability conditions
Solution Approach 1:
The patent enables the formation itself to provide wettability information through its natural dielectric response to multi-frequency electromagnetic fields. The formation's bound water fraction and dielectric dispersion characteristics directly reveal wettability properties in-situ, eliminating the need for external laboratory analysis and core sample retrieval.
Solution Approach 2:
The patent replaces mechanical laboratory measurement systems with electromagnetic field-based in-situ measurements. Instead of physically retrieving core samples for laboratory analysis, it uses electromagnetic waves to probe the formation's dielectric properties and derive wettability information directly downhole.
3Loss of information
If multi-frequency dielectric measurements are performed, then wettability information can be obtained, but the measurement and analysis process becomes more complex
Solution Approach 1:
The patent makes the dielectric measurement tool multi-functional by enabling it to simultaneously determine water saturation, wettability indices, and bound water fraction from the same multi-frequency measurements. The same electromagnetic measurement system serves multiple interpretation purposes, reducing the need for separate specialized tools.
Solution Approach 2:
The patent changes the measurement parameters by utilizing multiple frequencies rather than a single frequency. This parameter change enables the extraction of frequency-dependent dielectric dispersion characteristics, which contain additional information about bound water and wettability that is not accessible with single-frequency measurements.
4Ease of operation
If conventional electromagnetic tools are used in cased wellbores, then measurements can be made, but conductive casing limits the electromagnetic signal
Solution Approach 1:
The patent applies preliminary action by using high-frequency electromagnetic signals that are transmitted through the cased wellbore before the actual formation evaluation measurements. The system characterizes the casing's electromagnetic response in advance and uses this information to correct and compensate for signal attenuation and distortion during the formation measurements.
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 allows for an in-situ, quantitative estimation of reservoir wettability, improving the accuracy of oil saturation and production estimates by accounting for geometrical effects and thermodynamic conditions, validated through laboratory and field data.
Implementation Method 1
Multi-frequency dielectric dispersion measurements are made using the multi-frequency dielectric measurement tool on a sample
Implementation Method 2
a signal originates from a tool disposed in the interior of an uncased wellbore, passes through the formation outside the wellbore, and returns to a receiver within the wellbore
Data Source
AI summary
The wettability of a formation may be estimated using a multi-frequency dielectric measurement tool. Multi-frequency dielectric dispersion measurements are made using the multi-frequency dielectric measurement tool on a sample. The bulk density and the total porosity of the sample are also otherwise acquired. The bulk density, matrix permittivity, total porosity, and multi-frequency dielectric dispersion measurements are input into a petrophysical dielectric model and the petrophysical dielectric model is applied to obtain inversion results. A wettability state of the sample is determined using the inversion results and one or more reservoir management decisions are made based on the determined wettability state of the sample. A non-transitory, computer-readable storage medium may be provided that has stored on it one or more programs that provide instructions. The instructions are executed by a processor and cause the processor to develop an estimation of formation wettability that may be used for reservoir management.