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自从二十世纪五十年代开始,烃类生成被认为是最重要的异常压力机制之一。烃类生成影响孔隙—压力演化:(1)通过固体干酪根向液态或气态烃类的转化增加孔隙流体的体积;(2)由于烃类在孔隙水中保持非混溶相,减少了沉积岩的渗透率。本文中,假定有机质分解的两个产物液态烃(石油〕和气态烃(甲烷)作为孔隙中的补充相存在于地层中,并成为评价这一压力机制有效性的基础。用一个简化的三步一级动力学反应模型模拟油气的生成。我们用两相水动力公式的盆地数值模拟计算有机质成熟对地压演化的影响。除了在岩石有机质含量比较大(>5%)的情况下,否则,石油生成没起重要作用,然而气的生成有很大影响。结果表明,在一定埋深下,油至气的裂解强烈地影响超压。随着岩石有机质含量增加,这一机制的作用变得更加重要。一些环境条件,像干酪根类型、温度梯度和岩石性质,不同程度地影响有机质成熟对超压发育的作用。
Since the 1950s, hydrocarbon generation has been considered as one of the most important abnormal pressure mechanisms. Hydrocarbon generation affects pore-pressure evolution: (1) increases the volume of pore fluid by the conversion of solid kerogen to liquid or gaseous hydrocarbons; (2) reduces the infiltration of sedimentary rocks as the hydrocarbons remain immiscible in pore water rate. In this paper, it is assumed that the two products of organic matter, liquid hydrocarbons (petroleum) and gaseous hydrocarbons (methane), are present in the formation as complementary phases in the pores and form the basis for evaluating the effectiveness of this pressure mechanism. First-order kinetic reaction model is used to simulate the formation of oil and gas. We use two-phase hydrodynamics basin numerical simulation to calculate the effect of organic matter maturation on the evolution of ground pressure. Except for a large organic matter content (> 5%), The formation of gas did not play an important role, however, the generation of gas had a great effect.The results show that the cracking of oil-to-gas strongly affects overpressure at a certain depth, and as the rock organic matter content increases, the mechanism becomes More important.Some environmental conditions, such as kerogen type, temperature gradient and rock properties, affect the maturation of organic matter to overpressure development in varying degrees.