长岭断陷南部断陷层湖相优质烃源岩发育控制因素  

Controlling factors of high-quality lacustrine hydrocarbon source rocks in southern Changling Depression

作　　者：李浩[1] 陆建林[1] 左宗鑫 王保华[1] 李瑞磊[2] 刘娅昭[1] 

机构地区：[1]中国石化石油勘探开发研究院无锡石油地质研究所,江苏无锡214126 [2]中国石化东北油气分公司勘探开发研究院,吉林长春130062

出　　处：《石油与天然气地质》2015年第2期209-218,229,共11页Oil & Gas Geology

基　　金：中国石化科技部项目"长岭断陷结构充填特征及有利成藏组合研究"(P13073)

摘　　要：明确湖相优质烃源岩形成的主控因素对其非均质性的刻画意义重大。对松辽盆地长岭断陷南部地区沙河子组和营城组两套烃源岩进行岩石学、地球化学和层序地层学分析,并利用元素含量比Al/Ti值评估烃源岩古生产力,同时利用V/Cr、V/(V+Ni)、Sr丰度、Sr/Ba、Sr/Cu和古气候指数来评估沉积环境。研究表明,长岭断陷断陷层优质烃源岩层位(沙河子组上部)发育于原始生产力中等、气候潮湿、低盐度、沉积速率较低的高位域和湖侵域,具有富集Al,Ba,Cu,Cr,V和Ni,亏损Mn,Pb和S的特征;而差烃源岩层位(营城组)发育于原始生产力较低、气候半干燥、半咸水、沉积速率较高的低位域,具有富集Co,Sr和V,亏损Al,Ba,Cr,Cu,Mn,Pb和Ni的特征。由此认为,体系域控制了烃源岩的宏观分布,中等-好的初级生产力是优质烃源岩发育的首要条件,而潮湿气候、较低的盐度和沉积速率促进了有机质的富集。Heterogeneity study of lacustrine source rocks relys heavily on a deeper understanding of the major controlling factors on their formation. Geochemical,petrological and sequence stratigraphy analyses of two sets of source rocks（ K1 sh and K1 yc） in southern Changling Depression,Soliao Basin,reveal that multiple factors played roles in shaping the distri-bution of organic matters there. Al/Ti ratio was used to evaluate their paleoproductivity. Parameters like V/Cr,V/（ V＋Ni） ,Sr concentration,Sr/Ba,and Sr/Cu as well as paleoclimatic indexes,were also employed to study their sedimentary settings. Results show that high-quality source rocks（ mainly in upper Shahezi Formation） were developed in a highstand system tract and lacustrine transgressive system tract that featured in medium paleoproductivity,humid paleoclimate,low paleosalinity and low deposition rate. They are rich in Al,Ba,Cu,Cr,V and Ni,but lack of Mn and S. Meanwhile,low-quality source rocks（ maninly found in the Yingcheng Formation） ,were developed in lowstand system tract（ LST） that was characterized by low paleoproductivity,semi-arid paleoclimate,high paleosalinity and high deposition rate. They are abun-dant in Co,Sr and V but lack of Al,Ba,Cr,Cu,Mn and Ni. We therefore suggest that,in the study area,（1）system tracts controlled the distribution of source rocks,（2） moderate-to-good primary productivity was a critical precondition for the development of high-quality source rocks,and（3）humid climate,low salinity as well as favorable sedimentation rate,were the reasons behind organic matter accumlations.

关 键 词：微量元素 古生产力 沉积环境 优质烃源岩 长岭断陷 松辽盆地 

分 类 号：TE121.3[石油与天然气工程—油气勘探]