东营凹陷烃源岩排烃的地质地球化学特征

陈中红等，地球化学，2005，34（1）：79-87

摘要：利用地质地球化学信息研究烃源岩的排烃行为是一种重要而有效手段，东营凹陷较为丰富的地质地球化学信息对研究烃源岩的排烃行为具有重要的意义。东营凹陷烃源岩排烃的地质地球化学特征显示其排烃行为存在较强的非均质性：单层泥岩边缘地区排烃效率高，单层泥岩内部排烃效率相对较低，这种现象在厚层泥岩中（大于30m）表现更为明显，其中通常存在一定的相对“滞排区”；不同的压实阶段，排烃效率也不相同，快速压实带较缓慢压实带及稳定压实带排烃效率稍高。东营凹陷存在两类超压体系：一类是相对开放性质的，幕式排烃是其重要的排烃方式之一，其排烃效率较常压系统高，排烃效率平均在50%左右（常压体系排烃效率一般在40%左右）；另一类是相对封闭性的，为良好的超压“封存箱”，其排烃效率较常压系统低，排烃效率平均在20%左右，其地质地球化学行为显示一定的滞排特征，排烃行为不明显。研究结果认为压实不均衡是东营凹陷形成沙三中异常高压的主要原因，生烃作用是其形成沙四上超压的主要机制，而沙三下同时具备压实不均衡及生烃作用的双向增压效应。

关键词：东营凹陷；地质地球化学；烃源岩；压实；排烃；超压

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The Geochemistry Characteristics of hydrocarbon expulsion from source rocks in Dongying depression

Chen Zhonghong, et al，GEOCHIMICA，2005，34（1）：79-87

(The University of Petroleum, Dongying, Shandong, China,257061)

Abstract: Using geochemistry information to study hydrocarbon-expulsion behavior is an important and effective measure. The abundance of the geochemistry information in Dongying depression has great significance in studying hydrocarbon-expulsion behavior. The geochemistry characteristics indicated that  the hydrocarbon-expulsion in Dongying depression had stronger heterogeneity: the efficiency of hydrocarbon-expulsion in the edge of mud is much higher than the inner of the mud; the efficiency of hydrocarbon-expulsion in the edge of mud was much higher than in the inner of the mud, which was more obvious in the thick mud (thicker than 30m) , and there were stagnant-expulsion zone in the thicker mud commonly; in different compaction phase the efficiency of hydrocarbon-expulsion had discrepancy, the efficiency of hydrocarbon-expulsion in the rapid-compaction phase was higher than in the slow-compaction phase and the stabilized-compaction phase. There were two types of overpressured systems: the open and the closed relatively. The episodic hydrocarbon-expulsion was an important hydrocarbon-expulsion behavior in the open system, and its efficiency was higher comparatively (50% averagely, higher than 40% in normal pressure system); the closed system was overpressure compartment and its efficiency of hydrocarbon expulsion is lower (averagely 20%), and the characteristics of geochemistry demonstrated the stagnant-expulsion. The disequilibrium compaction was considered to be the primary reason for the overpressure formation in the middle part of the Member 3 of Shahejie Formation, hydrocarbon-generation was the key factor for the overpressure in the upper part of the Member 4 of Shahejie Formation, and the overpressure in the lower part of the Member 3 of Shahejie Formation was a result of the both factors.

Key words: Dongying depression; geochemistry; source rocks; compaction; hydrocarbon-expulsion；overpressure

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