Method for quantitatively judging thermal cracking degree of crude oil and application of method

Abstract

The invention discloses a method for quantitatively judging the thermal cracking degree of crude oil. By using the methylcyclohexane / dimethylcyclopentane mass ratio and the xylene / normal octane mass ratio as judgment indexes, the thermal cracking degree of the crude oil is quantitatively judged. Through the method, the thermal cracking degree of the crude oil subjected to thermal alteration can bequantitatively judged, the cause type of the crude oil can be effectively identified, and a scientific basis is provided for correctly evaluating effective hydrocarbon source rocks and evaluating thepotential of cracking gas.

Description

technical field [0001] The invention belongs to the technical field of petroleum exploration and development research, and in particular relates to a method for quantitatively judging the thermal cracking degree of crude oil and its application. Background technique [0002] The analysis of the origin type of crude oil is the basic work of oil and gas exploration. Traditional research on the genetic type of crude oil focuses on the analysis of hydrocarbon-generating parent material type, maturity, and depositional environment. At the same time, researchers also noticed that epigenetic alterations such as thermal effects can change the geochemical appearance of crude oil and affect the analysis of its genetic type. It is a common geochemical method to study thermal alteration through thermal simulation experiments. More and more researchers pay attention to the importance of epigenetic alteration and carry out related work. The research work on thermal alteration is constant...

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Problems solved by technology

There are several problems in judging the thermal cracking degree of crude oil by using the content of adamantane: ① There is one biggest limitation in the application of adamantane in different exploration blocks, that is, it is difficult to determine the adamantane line of crude oil in each area; Unclear, making its application uncertain; ③The quantitative method of adamantane is complicated and the test cost is high, and there are few relevant units for quantitative analysis of adamantine at home and abroad, which limits the application of this technology

[0004] In "Simulation Experimental Research on Quantitative Characterization of Crude Oil Thermal Cracking Degree" (CNKI Geochemistry, 2010.01) and (2009.12) "Simulation Experimental Research on Quantitative Description of Crude Oil Thermal Cracking Degree" (Xinjiang Petroleum and Natural Gas, 2009.12), it is reported that the application of heat The simulation experiment technology studies the different geochemical characteristics of the simulated products that undergo thermal cracking. This method has the following disadvantages: If the degree of thermal cracking of crude oil is quantitatively studied based on the absolute concentration of related compounds in the aromatic components, it is necessary to analyze the aromatic hydrocarbons in the crude oil sample. For quantitative testing and analysis of compounds, crude oil samples with different biostandard concentrations need to adjust the amount of standard samples during the testing process. The experimental process is cumbersome and the testing cost is high; For mixed crude oils that have undergone multiple stages of accumulation, the aromatic components are more of the geochemical characteristics of crude oils with lower maturity in the early stage, and cannot accurately indicate the geochemical characteristics of crude oils with higher maturity in the later stage after thermal alteration. chemical characteristics

[0005] "Geochemical evolution characteristics of crude oil cracking under different pressure systems" (Science in China, 2013.10) and "Thermal evolution characteristics of deep crude oil in the Tarim Basin-Evidence from thermal simulation experiments" (Journal of Applied Basic and Engineering Sciences, 2015.12), described in detail After the crude oil undergoes thermal simulation, the isoprenoids, steranes, and terpenes of the liquid hydrocarbon products are commonly used to characterize the changes in the parameters of the maturity during the thermal evolution process. It is considered that these parameters are at Ro>1.0% has reached the equilibrium value, but with the increase of the degree of thermal evolution, the change trend is very complicated, most of them present a wave-like change trend, and it is difficult to quantitatively identify the plate

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