Core Wettability Characterization via Dynamic Mass Imbibition
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Solution Overview
Problem
Current methods for determining reservoir rock wettability, such as the Amott and USBM tests, are insensitive near neutral wettability, require complex setups, and cannot accurately measure fractional or mixed wettability, leading to imprecise results and experimental challenges.
Innovation Solution
The Rise in Core (RIC) method employs the Washburn Equation for dynamic determination of contact angles, using a modified form of the equation to characterize wettability across a broad range of conditions from strongly water-wet to strongly oil-wet, requiring minimal equipment and simpler experimental procedures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional methods (Amott and USBM tests) are used to determine reservoir rock wettability, then wettability can be measured, but the methods are insensitive near neutral wettability and cannot accurately measure fractional or mixed wettability
Solution Approach 1:
The patent applies parameter changes by monitoring the change in mass of the core sample over time during imbibition, rather than using static endpoint measurements. The Washburn equation relates the square of the imbibition height (or mass change) to time, allowing dynamic tracking of the imbibition process. This enables differentiation between various wettability states including neutral and fractional wettability by analyzing the rate and extent of fluid uptake.
2Measurement precision
If traditional methods (Amott and USBM tests) are used to determine reservoir rock wettability, then wettability can be measured, but complex equipment and experimental setups are required
Solution Approach 1:
The patent extracts the essential measurement principle from complex traditional methods by using only the basic Washburn equation approach with minimal equipment. Instead of requiring complex centrifugal or pressure systems used in Amott and USBM methods, the invention uses simple imbibition experiments monitored by mass change measurements, isolating the core physical principle from unnecessary experimental complexity.
Solution Approach 2:
The patent replaces complex mechanical systems (centrifuges, pressure controllers, multiple fluid injection systems) with a simple gravitational imbibition system. The core sample is simply hung allowing spontaneous imbibition to occur under gravity, and the process is monitored by measuring mass change over time using a balance, substituting mechanical complexity with a simpler gravitational field-based system.
3Measurement precision
If traditional methods (Amott and USBM tests) are used to determine reservoir rock wettability, then wettability can be measured, but the procedures are time-consuming and require multiple experimental steps
Solution Approach 1:
The patent applies continuity of useful action by performing continuous mass measurements during the imbibition process rather than taking discrete endpoint measurements. The core sample mass is monitored continuously or at frequent intervals as imbibition proceeds, allowing the entire imbibition curve to be captured in a single experiment. This eliminates the need for multiple separate experimental steps required by traditional methods to determine different wettability parameters.
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
The RIC method provides quick, accurate, and reproducible measurements of wettability, capable of characterizing any type of reservoir rock and fluid system, offering a more straightforward and effective approach compared to traditional methods.
Implementation Method 1
The imbibition process of the core sample with the imbibition liquid is commenced
Implementation Method 2
a modified form of the Washburn equation, which is normally used to determine wettability of liquid/air/powder system
Data Source
AI summary
The various embodiments herein provide a method for determining core wettability characteristics of reservoir rock samples based on modified form of Washburn equation. The method involves saturating a core sample with a first reservoir fluid such as water and imbibing with a second reservoir fluid such as oil. The change in square of the core mass with respect to time is monitored during an imbibition process to acquire a data to calculate a contact angle to determine the wettability of the sample. The contact angle is calculated by using the modified form of Washburn equation. A single or twin core sample is used to calculate the wettability characteristics. The method measures wettability characteristics in terms of contact angle and not in terms of wettability index.