Physical properties of Cenozoic mudstones from the northern North Sea: Impact of clay mineralogy on compaction trends
Physical properties of Cenozoic mudstones from the northern North Sea: Impact of clay mineralogy on compaction trends
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DOI：
10.1306/08220808044
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发表时间：
2009
期刊：
影响因子：
3.5
通讯作者：
Ø. Marcussen;B. Thyberg;C. Peltonen;J. Jahren;K. Bjørlykke;J. Faleide
中科院分区：
文献类型：
--
作者：
Ø. Marcussen;B. Thyberg;C. Peltonen;J. Jahren;K. Bjørlykke;J. Faleide
北海盆地北方新生代泥岩物性的垂向和横向变化反映了原生矿物成分和埋藏史的差异，提供了沉积相和物源的信息。测井数据与矿物学信息的整合显示了不同粘土矿物学对泥岩压实曲线的影响。北海内始新世至早中新世泥岩压实的主要控制因素是蒙皂石含量，其来源于北海西北部的火山源。与埋深相同的其他粘土矿物组合的泥岩相比，具有高蒙皂石含量的泥岩的特征在于较低的P波速度和体积密度。蒙皂石粘土在机械压实过程中很重要，因为它们比其他类型的粘土矿物压缩性更低。测井资料与实验结果的对比也表明，在富含蒙脱石的始新统和渐新世沉积物中，蒙脱石可能是超压产生的控制因素。在更大的埋藏深度和温度（70- 80 ℃），蒙脱石的溶解和伊利石和石英的沉淀显着增加速度和密度。北海北方中新世和更年轻的泥岩通常具有较低的蒙皂石含量，因此具有比始新世和渐新世泥岩更高的速度和密度。这些沉积物的压实趋势在南北方向上也存在差异，这可能与上新世两个不同的物源区有关。北海盆地北方的测井岩石物理数据表明，泥岩岩性具有非常不同的压实趋势取决于主要成分。因此，简化的压实曲线可能会影响盆地模拟的结果。烃类砂岩的振幅-偏移距响应和地震剖面上的地震特征也取决于泥岩的岩石物理性质，并将根据矿物成分而变化。
Vertical and lateral changes in physical properties in Cenozoic mudstones from the northern North Sea Basin reflect differences in the primary mineralogical composition and burial history, which provides information about sedimentary facies and provenance. Integration of well-log data with mineralogical information shows the effect of varying clay mineralogy on compaction curves in mudstones. The main controlling factor for the compaction of Eocene to early Miocene mudstones within the North Sea is the smectite content, which is derived from volcanic sources located northwest of the North Sea. Mudstones with high smectite content are characterized by low P-wave velocities and bulk densities compared to mudstones with other clay mineral assemblages at the same burial depths. Smectitic clays are important during mechanical compaction because they are less compressible than other types of clay minerals. A comparison between well-log data and experimental work also shows that smectite may be a controlling factor for overpressure generation in the smectite-rich Eocene and Oligocene sediments. At greater burial depths and temperatures (70–80C), the dissolution of smectite and precipitation of illite and quartz significantly increases velocities and densities. Miocene and younger mudstones from the northern North Sea have generally low smectite contents and as a result have higher velocities and densities than Eocene and Oligocene mudstones. Lateral differences in the compaction trends between the north and south for these sediments also exist, which may be related to two different source areas in the Pliocene. The log-derived petrophysical data from the northern North Sea Basin show that mudstone lithologies have very different compaction trends depending on the primary composition. Simplified compaction curves may therefore affect the outcomes from basin modeling. The amplitude-versus-offset response of hydrocarbon sands and the seismic signature on seismic sections are also dependent on the petrophysical properties of mudstones and will vary depending on the mineralogical composition.