碳酸盐烃源岩排烃的若干特点  

SOME CHARACTERISTICS OF HYDROCARBON EXPULSION IN CARBONATE SOURCE ROCKS

作　　者：汪本善[1] 张丽洁[1] 麦碧娴[1] 邢福建[1] 

机构地区：[1]中国科学院广州地球化学研究所

出　　处：《地球化学》1996年第4期317-323,共7页Geochimica

摘　　要：通过典型碳酸盐型油气田的野外调查研究和对未成熟碳酸盐生油岩在外加温、外加压条件下所作的生烃一排烃模拟实验结果，获得下列新的认识：（１）碳酸盐烃源岩排烃的驱动力主要不是来自地层的压实作用，而是由于生烃过程中分子体积膨胀所产生的内应力（即生烃增压）。该应力与周围环境形成潜在的压力梯度，这是排驱动力的内在因素。但是单凭此因素尚不足以造成排烃，只有当后来烃源层受到外力作用（如导致微裂隙产生的区域性构造活动、造成溶蚀交代出现缝缝洞洞的地下水活动等）生成裂隙空间，并在源岩与裂隙间出现真正的压差时，才引发烃源层中积蓄的应力释放，从而造成排烃。因此、区域性的外力作用是排烃的控制因素。（２）碳酸盐烃源岩中生烃时间甚早，一般在Ｒ＿０为０．４５％左右时就开始生成低熟原油。但由于碳酸岩岩石粒间孔径甚小，虽有低熟油生成，却不能象泥质烃源岩那样在其烃浓度超过最低石油运移饱和度时就可排烃。事实证明，无论生烃量多大，只要碳酸盐烃源岩中不出现有效的通道，排烃作用可能永远不会进行。因此，当碳酸盐烃源岩中油气生成之后，裂隙发生的时间就成为决定碳酸盐烃源岩排烃时间的基本因素。（３）碳酸盐烃源岩中烃类初次运移基本上是以全烃相进行的，这与碳酸盐岩在后?Based on the investigations of carbonate source rocks, which had expelled oil and gas in the past, and studies of simulation experiments about the generating and expelling hydrocarbons in carbonate rock at a series of temperature and pressure conditions. In this paper, the following novel points have been submitted:1.The expulsion energy of carbonate source rock mainly come from the increasing pressure within itself caused by the great increase in molar volumes with the generating and further cracking of hydrocarbons. However, the hydrocarbons would still be sealed untill micro-fracture appears in the rock caused by regional tectogene or exogenetic actions. In those cases, only by relying on the initiation of outside force, intrinsic pressure does be the expulsion energy. Compaction doesn't be expulsion factor due to the diagenesis-catagenesis particularities of carbonate rocks.2. Although the oil-generating time of carbonate source rock is earlier, generally the immature crude oil has been generated at R_0≈0.45%, yet the oil-expelling time would be delayed owing to missing the micro-fracture in rocks. Therefore, hydrocarbon-expelling time of carbonate source rock is controlled mainly by its fracturing time, not by its thermal evolutional stage.3. Basically, the phases of hydrocarbons of carbonate source rock during primary migration are oil and gas. It may be suggested that the release of either mineral crystallization water or free water have not being in catagenetic and metagenetic stages of carbonate rocks.

关 键 词：碳酸盐 烃源岩 排烃 油矿床 天然气矿床 

分 类 号：P618.130.5[天文地球—矿床学]