Downhole Asphaltene Analysis via Size Exclusion Chromatography
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Solution Overview
Problem
Current downhole fluid analysis techniques are limited by the extreme conditions of the well environment, restricting the measurement of fluid properties to a small subset of those available in conventional surface laboratory analysis, which hampers accurate reservoir modeling and optimization.
Innovation Solution
A downhole tool equipped with a size exclusion chromatography module, including a solvent reservoir, dilution module, and size exclusion separation module, performs size exclusion chromatography to estimate properties like average molecular weight, API density, and asphaltene content of hydrocarbon samples, providing more detailed chemical composition information for reservoir modeling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If downhole fluid analysis is performed using conventional DFA techniques, then fluid property information can be obtained at downhole conditions, but the measurement capability is limited to a small subset of properties due to extreme downhole conditions
Solution Approach 1:
The downhole tool is divided into functional modules: a sampling module for obtaining fluid samples, a chromatography module for separating components, and a detection module for analyzing properties. This segmentation allows each module to be optimized for its specific function while working together to provide comprehensive fluid analysis capability that overcomes the limitations of conventional DFA techniques
Solution Approach 2:
A chromatography column acts as an intermediary between the downhole environment and the detection system. The column separates complex hydrocarbon mixtures into individual components that can then be detected and quantified, enabling detailed compositional analysis that would otherwise be impossible under extreme downhole conditions
2Loss of information
If surface laboratory analysis is used to measure comprehensive fluid properties, then detailed chemical composition information is available, but samples must be brought to surface conditions which may alter fluid properties
Solution Approach 1:
The system performs preliminary separation and analysis actions downhole before the fluid sample is brought to the surface. By conducting chromatography separation and property measurements at downhole conditions, the system preserves the fluid's native state and avoids property changes that would occur during transport to surface laboratories
Solution Approach 2:
The downhole tool performs self-analysis by integrating sampling, separation, and detection capabilities within the tool itself. The system autonomously analyzes fluid properties at the measurement location, eliminating the need to transport samples to surface laboratories and ensuring that measurements reflect true downhole conditions
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
Enables real-time, detailed chemical composition analysis of hydrocarbon samples, enhancing reservoir modeling and optimization by providing comprehensive data on molecular weight distribution and asphaltene content, thereby improving production strategies.
Implementation Method 1
The size exclusion separation module includes at least one size exclusion chromatography column configured to receive solvent and at least a portion of the hydrocarbon liquid sample from the injection module
Data Source
AI summary
A system and method for determining the asphaltene content of a downhole oil sample are provided. In one example, the method includes obtaining a hydrocarbon sample from a hydrocarbon formation of a reservoir at a given depth using a downhole tool. A liquid phase of the hydrocarbon sample is isolated within the downhole tool and the liquid phase is subjected to downhole analysis within the downhole tool to create a chromatography sample. The downhole analysis is based at least partially on size exclusion chromatography. A first property of the chromatography sample is measured to obtain a measured value, and a second property of the chromatography sample is estimated based on the measured value and known calibration curves.