摘要
烃源岩评价是深水区油气勘探非常关键的问题,由于深水区没有井钻穿始新统,所以本研究只能根据相邻浅水区钻井和区域对比的方法,通过层序地层格架、沉积相、地震相、地震速度岩性等资料与相邻地区对比识别烃源岩,确定烃源岩的性质和分布。白云凹陷古近系地层沉积中,沉积密集段具有如下特征:(1)准层序逐步向岸推进;(2)陆源碎屑物质供应不足;(3)水体相对较深的中深湖细粒沉积发育。地震反射特征与有利烃源岩具有良好的对应关系,白云凹陷恩平组湖扩体系域和文昌组湖扩体系域发育中弱振幅、中低频率和中高连续性地震相,是有利烃源岩发育区。利用单井资料建立起一个通过孔隙度来预测烃源层有机质成熟度的预测模型,泥岩孔隙度可以较容易从地震信息中获取,从而对白云凹陷的烃源层的热演化程度进行初步评价。根据沉积相与有机相的关系,直接将沉积相转换为有机相,预测有机相类型。在白云凹陷深水烃源岩预测实践的基础上,本文总结了一套深水区烃源岩早期评价方法,包括:(1)层序格架分析法确定有利烃源岩发育的垂向位置;(2)地震反射特征分析法确定烃源岩的横向分布范围;(3)根据泥岩层速度计算烃源岩热成熟度;(4)沉积相转有机相预测有机相类型。(5)对烃源岩进行综合评价优选次洼。
Source rock is very important for deepwater. Because there is no well piercing the Eocene strata, regional correlation method is applied to identify the source rock and define its distribution in Baiyun Depression, including the correlation of subsidence rate, sedimentary facies, seismic facies and seismic velocity lithology with the adjacent areas. The condensed section in the Paleogene strata of Baiyun Depression has three features： ① parasequences moved forward the shore ; ② the supply of terrigenous detrital material was not enough ; ③semideep lacustrine fine sediment developed well. The seismic reflection characters are well corresponding to the favored source rock. The seismic facies of medium-weak amplitude, medium-low frequency and medium-high continuity of lake progressive system tracts of Enping and Wenchang Formation in Baiyun Depression is the area of favored source rock. A forecast model is built up for the degree of organic maturity of source beds with single well and the mudstone porosity which can be got easily from the seismic information. This model is then applied to evaluate the thermal evolution degree of the source beds in Baiyun depression preliminarily. Based on the research of Baiyun depression, this paper represents a Methodology of evaluation on source rocks of deep water. This methodology includes five aspects： （ 1 ） analysis of sequence stratigraphy to determine the main formation of source rocks, （2） analysis of seismic reflectance signature to determine the occurring position of source rocks, （3） prediction of vitrinite reflectance based on mudstone velocity to determine the maturation of source rocks, （4） prediction of types of organic facies based on the conversion from sedimentary facies to organic facies, （5） comprehensive evaluation to select optimum hydrocarbon-generating sag.
出处
《沉积学报》
CAS
CSCD
北大核心
2007年第1期139-146,共8页
Acta Sedimentologica Sinica
关键词
沉积密集段
地震相
沉积相
有机质成熟度
condensed section, seismic facies, sedimentary facies, organic maturity
