利用地震信息定量预测烃源岩热成熟度——以琼东南盆地乐东—陵水凹陷为例  

Source rock maturity quantitative prediction using seismic information,a case study in the LedongLingshui Depression,Qiongdongnan Basin

作　　者：黄艳辉[1] 刘震[1] 陈婕[1] 郭志峰[1] 武彦[1] 孙志鹏[2] 

机构地区：[1]中国石油大学(北京)地球科学学院油气资源与探测国家重点实验室,北京102249 [2]中国海洋石油有限公司湛江分公司技术部,广东湛江524057

出　　处：《石油地球物理勘探》2013年第6期985-994,1016+853,共10页Oil Geophysical Prospecting

基　　金：国家重点基础研究发展计划(973)项目"南海深水盆地油气资源形成与分布基础性研究"(2009CB219400);国家重大科技专项项目"南海北部深水区成藏组合评价研究"(2011ZX05025-002-05)联合资助

摘　　要：琼东南盆地深水区钻测井数量少、钻遇层位浅和难以获取高精度地层速度,不利于有机质成熟度的预测。为此,本文从烃源岩镜质体反射率—孔隙度(Ro-Φ)预测模型建立和地层速度提取两个关键环节入手,形成了一套适用于琼东南盆地乐东—陵水凹陷的烃源岩成熟度地震定量预测方法:①采用研究区及邻区烃源岩Ro与Φ的乘方关系,建立了烃源岩Ro-Φ预测模型;②利用有色反演方法确定了相对速度分量与低频速度分量,再将相对速度分量与低频速度分量合成为频带适中的地震绝对速度。对比Ro-TTI方法与本文采用的Ro-Φ方法的烃源岩成熟度预测效果可知:前者预测有机质成熟度精度更高,适用于勘探程度较高的地区;后者主要基于地震、钻井和地质资料,可以从宏观上了解烃源岩的空间展布及生烃潜力,适用于勘探程度较低的地区。古近系烃源岩成熟度的地震定量预测结果表明,古近系烃源岩在凹陷中心部位成熟度较高,向四周逐步降低,表现为:古近系上部渐新统(陵水组、崖城组)烃源岩达到成熟—高成熟阶段,局部地区甚至达到过成熟阶段,现今及成藏期对本区供烃具有重要贡献,其中崖城组烃源岩生烃最为有利;下部始新统烃源岩在全区几乎处于过成熟阶段。Actual conditions in deepwater areas of Qiongdongnan Basin,such as sparse well controls, shallow-drilling depth,and low-precise formation velocity,are not conducive to organic maturity prediction.Therefore,based onRo-Φ 'prediction model building for source rock and formation velocity extract,this paper proposes an applicable organic matter quantitative prediction method by the use of seismic data from the Ledong-Lingshui Depression,Qiongdongnan Basin.First we establishRo-Φ' prediction model for source rock using the power relationship of organic matter maturity(Ro)and mudstone porosity(Φ)in the study area and its adjacent area.Then using colored inversion method we determine low frequency velocity and relative velocity,and compose relative velocity component and low frequency velocity component to seismic absolute velocity in a moderate broadband.On the comparison of organic matter maturity prediction,Ro-TTI ' method predicts organic matter maturity with higher accuracy,and is suitable for high degree exploration areas.Based on seismic,drilling and geological data,Ro-Φ' method can be used to understand the spatial distribution of source rocks and hydrocarbon potential,and is suitable for low degree exploration areas. Quantitative prediction results of Paleogene source rock maturity show that Paleogene source rock maturity is relatively high in the center part of the Ledong-Lingshui Depression,and gradually reduced towards the boundary.Source rocks of Upper Oligocene strata including Lingshui formation and Yacheng formation have reached high maturation stage,some of them even have reached over-mature stage which make important contributions to hydrocarbon accumulation in the area.Source rock of Yacheng formation is the most favorable for hydrocarbon generation.Source rock of Lower Oligocene strata is almost in over-matured stage.

关 键 词：琼东南盆地深水区 乐东-陵水凹陷 烃源岩 R0-φ垂预测模型 地震绝对速度 有色反演 

分 类 号：P631[天文地球—地质矿产勘探]