Step-wise Pyrolysis Gas Chromatography for Kerogen Maturity
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Solution Overview
Problem
Current methods fail to accurately determine the degree of transformation of kerogen to hydrocarbons at different maturity levels, making it difficult to assess when shale will start generating significant oil and gas, and optimizing pyrolysis conditions for oil shale conversion.
Innovation Solution
A step-wise pyrolysis gas chromatographic method that heats shale samples at increasing temperatures, analyzing hydrocarbons generated at each step to quantify kerogen conversion to gas, light oil, and heavy oil, and correlating pyrolysis conditions to equivalent maturity levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional single-temperature pyrolysis is used, then the analysis is simple and quick, but it cannot determine the degree of kerogen transformation at different maturity levels
Solution Approach 1:
The pyrolysis process is divided into multiple temperature steps (e.g., 300°C, 400°C, 500°C, 600°C) instead of using a single temperature. Each step allows measurement of hydrocarbon generation at different maturity levels, enabling determination of kerogen transformation degree at various stages of maturation.
Solution Approach 2:
The pyrolysis temperature is changed in a step-wise manner from 300°C to 600°C or higher, simulating the progressive increase in geological maturity. This parameter change allows the system to capture hydrocarbon generation at different maturity stages, providing detailed transformation data.
2Loss of information
If step-wise pyrolysis at multiple temperatures is implemented, then transformation ratios at different maturities can be determined, but the analysis time and complexity increase
Solution Approach 1:
The method performs preliminary measurements at multiple temperature steps before complete maturation occurs. By measuring hydrocarbon generation at each temperature step (300°C, 400°C, 500°C, 600°C), the method captures information about when oil generation begins, when gas generation begins, and the progression of transformation, preventing loss of this critical timing information.
Solution Approach 2:
The pyrolysis process continues progressively through multiple temperature steps, with each step building on the previous one. The same sample is subjected to increasing temperatures in sequence, maintaining continuous measurement of transformation ratios and providing a complete picture of the maturation process without interrupting the useful action of hydrocarbon generation simulation.
3Reliability
If pyrolysis temperature is increased to simulate higher maturity, then more complete hydrocarbon generation is achieved, but the risk of secondary cracking and information loss increases
Solution Approach 1:
The high temperature pyrolysis process is segmented into multiple smaller temperature increments (300°C, 400°C, 500°C, 600°C). Each step allows hydrocarbons to generate and be measured before the temperature is increased further, preventing secondary cracking of already-formed hydrocarbons and maintaining reliability of the generation potential assessment.
Solution Approach 2:
The method rushes through the temperature increase in controlled steps rather than gradually heating to maximum temperature. By quickly progressing through defined temperature steps and measuring at each stage, the method captures hydrocarbon generation data before secondary cracking can occur at excessively high temperatures.
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 method provides real data to calibrate petroleum system models, optimizing pyrolysis conditions for converting oil shale to hydrocarbons and determining the maturity at which oil and gas generation begins, offering precise transformation ratios and generation indices.
Implementation Method 1
the source rock is subjected to pyrolysis at increasing temperatures in step-wise manner
Implementation Method 2
kerogen becomes more mature when subjected to heating for long periods of time and is converted to hydrocarbons
Implementation Method 3
the hydrocarbons generated from shale sample pass through the capillary column of the GC and are separated in to different components in order of their boiling points
Data Source
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AI summary
A method for evaluating a degree of transformation ratio of kerogen to oil and/or gas and/or gas to oil generation index using a pyrolysis gas chromatography is disclosed. The method comprises providing (302) a rock sample in powdered form; determining (304), by a source rock analysis instrument, total organic carbon in said rock sample, remaining hydrocarbon generation potential in rock sample, and a maturity of rock sample; feeding said sample in a pyrolyzer if said sample satisfies a pre-defined condition; analyzing (306), said sample in said pyrolyzer, by heating said sample at a pre-specified pyrolysis temperature in pre-specified pyrolysis steps and for pre-specified pyrolysis time; determining (308), by a gas chromatograph, a peak area of hydrocarbons present in said sample analyzed; evaluating (310), in a said degree of transformation ratio of said sample to oil and/or gas and/or said gas to oil generation index.