SOME CHARACTERISTICS OF HYDROCARBON EXPULSION IN CARBONATE SOURCE ROCKS
Wang Benshan;Zhang Lijie;Mai Bixian;Xing Fujian (Guangzhou Institute of Geochemistry, Chinese Academy of Sciences.Guangzhou 510640)
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.
【CateGory Index】： P618.130.5