碳酸盐岩压溶埋藏史和排烃数值模拟模型初步探讨

Numerical Model about Pressure-solution Burial History and Hydrocarbon Expulsion of Carbonate Rock

压溶作用产生的缝合线是烃富集的场所及初次运移的通道。碳酸盐岩烃源岩压溶过程中,随着地层厚度和体积的减小,未熟和低熟油气会伴随孔隙流体一同排出。根据碳酸盐岩埋藏与压溶机理,提出了压溶的碳酸盐岩缝合线或溶解缝厚度恢复及其古厚度恢复的数学模型,同时结合碳酸盐岩基质和缝合线孔隙度随深度的变化曲线建立了定量计算碳酸盐烃源岩压溶排烃量的数学模型。上述数学模型的关键是确定压溶作用开始和结束的深度和时间。缝合线的厚度可根据岩心或岩石薄片直接测定。

Sutures caused by pressure solution are either a space for organic enrichment and hydrocarbon-forming or a conveyer for hydrocarbon primary migration.Immature and lower-mature oil and gas may be expelled with pore fluids as reduction of bed thickness and volume during pressure solution of carbonate source rock.A numerical model restoring paleothickness from suture (solution)thickness is put forward based on carbonate rock burial and pressure solution mechanism.Meanwhile a numerical model quantitatively calculating hydrocarbon expulsion caused by pressure solution of carbonate source rock is built up according to carbonate rock matrix and suture porosity change with depth.It is a key point of the model to determine the beginning and ending depth and time of pressure solution.The suture thickness may be measured based on cores or sections.