Lateral periodic variations in the petrophysical and geochemical properties of dolomite
Lateral periodic variations in the petrophysical and geochemical properties of dolomite
复制标题
白云石岩石物理和地球化学性质的横向周期性变化
作者：
D. Budd;M. Pranter;Z. Reza
密西西比系白云岩中微量元素浓度、孔隙度和渗透率的横向分布存在周期性振荡。#30 cm间距处的随机变化占总变异性的50%-70%。其余的变异发生在短期和长期振荡模式与周期为1.2-7.6米，这只能通过高分辨率采样的解决;150米横向断面。这些模式的成因可能是：（1）继承沉积先驱，（2）在石化过程中通过自组织过程形成，或（3）后期变形的叠加。到目前为止，这些振荡模式尚未被认识到，解决它们的起源和意义代表了一种新的研究方法。了解白云岩储层岩石物性的横向分布，可以改进白云岩油气藏流体流动模型和白云岩含水层基质与管道间污染物运移模型。此外，如果任何地层中地球化学属性的30%-50%的变异性是由于横向周期性造成的，那么人们必须问，这种变异性是否太大，以至于不能假设现场样品将是古代地质过程和条件的合适代表。
Mississippian dolowackestones contain periodic oscillations in the lateral distribution of trace-element concentrations, porosity, and permeability. Random variations at #30 cm spacing account for 50%-70% of the total variability. The remainder of the variability occurs in short- and long-range oscillatory patterns with periods of 1.2-7.6 m, which can only be resolved by high-resolution sampling of an ;150 m lateral transect. Possible origins for these patterns are: (1) inheritance from the depositional precursor, (2) for- mation by self-organizing processes during dolomitization, or (3) overprinting by late dia- genesis. These oscillatory patterns have up to now been unrecognized, and addressing their origin and meaning(s) represents a new approach to the study of dolomites. Under- standing the lateral distribution of petrophysical properties can also improve models of fluid flow in dolomite petroleum reservoirs and contaminant transport between matrix and conduits in dolomite aquifers. Further, if 30%-50% of the variability in a geochemical attribute in any bed is due to lateral periodicity, one must ask if that variability is too great to assume a spot sample will be a suitable proxy for ancient geologic processes and conditions.