应用碳同位素动力学模拟评价天然气的成因

简要介绍天然气形成过程中碳同位素分馏的理论基础、动力学参数模拟计算、碳同位素动力学模拟应用于天然气评价等方面的最新成果。揭露了几个值得注意的问题:天然气碳同位素特征不仅受母源、成熟度的影响,而且与运聚条件、沉积盆地增温速率有关;累积聚集气与阶段聚集气在碳同位素特征存在明显差别;碳同位素分馏动力学模型在不同盆地会存在差异,不仅取决于气源条件,还与聚集历史、沉积-构造史有关。我国天然气藏成因复杂,具有多期、多源的特点,对这类天然气的成因研究与评价提供了新思路。

The Origin Evaluation of Natural Gas With Carbon Isotope Kinetic Modeling

The origin evaluation of natural gas is more difficult than that of oil in petroleum exploration. At present, there are some obvious problems when the isotopic data are applied to the assessment of natural gas. The latest approach on the theoretical basis of carbon isotope fractionation, the calculation of kinetics parameters, and the application in the assessment of natural gas with carbon isotope kinetic modeling are briefly introduced in this paper. Some noticeable questions are also purposed as follows. The carbon isotopic characteristics of natural gas is not only affected by gas source and maturity, but also related to accumulation condition and thermal rate in a basin. There are obvious differences in the characteristics of carbon isotope ratios between instantaneous gas and cumulative gas. The kinetic model of carbon isotope fractionation may have difference in the different basin, which lies on gas source condition, accumulation history and sedimentary-tectonics history. As the origin of natural gas pool in our country is very complicated, and natural gas pool has the feature of multiphase and various gas source, this paper may provide a new thought for the origin assessment and research on this type of natural gas.