莺歌海盆地LD区块地层超压对泥岩成岩作用的影响及其地质意义  

Effects of Formation Overpressure on Mudstone Diagenesis and Its Geological Significance in LD Block of Yinggehai Basin

作　　者：段威[1,2] 罗程飞 黄向胜 吕波[3] 左晓东[3] 丁亮[1,2] 

机构地区：[1]中国地质大学构造与油气资源教育部重点实验室,武汉430074 [2]中国地质大学资源学院,武汉430074 [3]中海油能源发展股份有限公司工程技术分公司中海油实验中心,广东湛江524057

出　　处：《地质科技情报》2015年第4期43-50,共8页Geological Science and Technology Information

基　　金：十二五国家油气重大专项课题(2011ZX05023-006-007);构造与油气资源教育部重点实验室开放基金项目(TPR-2013-09);中国地质大学(武汉)中央高校基本科研业务费专项资金项目(1410491T04)

摘　　要：在综合前人研究基础上,应用X衍射、薄片鉴定、热解分析、生物标志化合物研究等技术,并与邻区的常压环境下的相关特征进行了对比,深入分析了莺歌海盆地LD区块地层超压的分布状况及其对黏土矿物转化和有机质热演化的影响。结果表明,1研究区内,超压顶界面深度从盆地中心向边缘逐渐变深;2研究区内,超压顶界面之上,随埋深和地温的增大,蒙脱石、伊蒙混层中蒙脱石和高岭石的含量逐渐降低,而伊利石和绿泥石含量逐渐增加,但超压顶界面附近及往下时,黏土矿物各组分的含量几乎不再减少,受到了地层超压作用的抑制;3Pr/nC17和Ph/nC18随深度增大而降低,但在强超压顶界面以下,变化趋势发生逆转,出现微弱增大的趋势,超压顶界面以下的实测Ro值即有机质的成熟度也出现了明显的低异常。地层超压通过抑制黏土矿物转化,间接减弱了储层的胶结作用,有利于深层优质储层的形成。研究区地层超压抑制了有机质的热演化,地层超压对生烃的抑制作用扩大了研究区有效源岩的层位和体积,并使主力源岩的生、排烃期后移,从而有利于油气的晚期快速聚集成藏。According to previous studies, we applied a serious of techniques, such as X-ray diffraction, thin section analysis, pyrolysis analysis and biological marker analysis, and then compared the related charac- teristics between the study area and adjacent normal pressure areas. Based on the previous work, we made a further analysis on the distribution of overpressure in LD block and its effects on clay mineral transfor- mation and thermal evolution of organic matter. The results show that： In study area, the depth of the top interface becomes deeper from basin center to margin. Over the interface of overpressure, with the increase of depth and geotemperature, the content of montmorillonite, illite mixed montmorillonite and ka- olinite gradually decreased, while the content of illite and chlorite increased. However, below the interface of overpressure, content of every component in clay mineral almost has no change which inhibited by for- mation overpressure. With the increase of depth, the ratio Pr/nC17 and Ph/nC18 decreased. While below the interface of strong overpressure, the trend reversed and even appeared slight increase. Ro values, the maturity of organic matter, which are measured below the overpressure interface, also appeared signifi- cantly abnormal lower. Overpressure indirectly weakens the reservoir＇ s cementation by inhibiting the transformation of clay minerals, which promotes the formation of deep and high-quality reservoir. Over- pressure in the study area inhibits the thermal evolution of organic matter. The inhibiting effect of over- pressure on hydrocarbon generation enlarges position and volume of the later valid source rock. It delays the hydrocarbon-generating and expulsion times of main source rock, which contributes to the late hydro- carbon accumulation.

关 键 词：莺歌海盆地 LD区块 地层超压 流体 黏土矿物 有机质 

分 类 号：TE122.221[石油与天然气工程—油气勘探]