Lommatzsch Marco, Exner Ulrike, Gier Susanne, Grasemann Bernhard
Department of Geodynamics and Sedimentology, University of Vienna, Althanstrasse 14, 1090 Vienna, Austria.
Department of Geology and Paleontology, Natural History Museum Vienna, Burgring 7, 1010 Vienna, Austria.
Mar Pet Geol. 2015 Apr 1;62:144-160. doi: 10.1016/j.marpetgeo.2015.02.002.
The present study examines deformation bands in calcareous arkosic sands. The investigated units can be considered as an equivalent to the Matzen field in the Vienna Basin (Austria), which is one of the most productive oil reservoirs in central Europe. The outcrop exposes carbonate-free and carbonatic sediments of Badenian age separated by a normal fault. Carbonatic sediments in the hanging wall of the normal fault develop dilation bands with minor shear displacements (< 2 mm), whereas carbonate-free sediments in the footwall develop cataclastic shear bands with up to 70 cm displacement. The cataclastic shear bands show a permeability reduction up to 3 orders of magnitude and strong baffling effects in the vadose zone. Carbonatic dilation bands show a permeability reduction of 1-2 orders of magnitude and no baffling structures. We distinguished two types of deformation bands in the carbonatic units, which differ in deformation mechanisms, distribution and composition. Full-cemented bands form as dilation bands with an intense syn-kinematic calcite cementation, whereas the younger loose-cemented bands are dilatant shear bands cemented by patchy calcite and clay minerals. All analyzed bands are characterized by a porosity and permeability reduction caused by grain fracturing and cementation. The changed petrophysical properties and especially the porosity evolution are closely related to diagenetic processes driven by varying pore fluids in different diagenetic environments. The deformation band evolution and sealing capacity is controlled by the initial host rock composition.
本研究考察了钙质长石砂岩中的变形带。所研究的单元可被视为相当于奥地利维也纳盆地的马岑油田，该油田是中欧产量最高的油藏之一。露头出露了巴登阶不含碳酸盐和含碳酸盐的沉积物，它们被一条正断层分隔开。正断层上盘的含碳酸盐沉积物发育了具有微小剪切位移（<2毫米）的扩张带，而下盘不含碳酸盐的沉积物则发育了位移达70厘米的碎裂剪切带。碎裂剪切带在渗流带的渗透率降低了3个数量级，并具有强烈的遮挡效应。含碳酸盐扩张带的渗透率降低了1 - 2个数量级，且没有遮挡构造。我们在含碳酸盐单元中区分出两种类型的变形带，它们在变形机制、分布和组成上有所不同。完全胶结带是作为具有强烈同构造方解石胶结作用的扩张带形成的，而较年轻的松散胶结带是由斑状方解石和粘土矿物胶结的扩张剪切带。所有分析的带都具有因颗粒破碎和胶结导致的孔隙度和渗透率降低的特征。岩石物理性质的变化，尤其是孔隙度的演化，与不同成岩环境中不同孔隙流体驱动的成岩过程密切相关。变形带的演化和封闭能力受初始母岩成分控制。
