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以鄂尔多斯盆地东部奥陶系风化壳为对象,以大量地质录井及实验分析资料为依据,密切结合古岩溶储层岩性和物性分析,综合探讨了古岩溶地貌与古岩溶储层的岩溶效应特征。研究结果表明,盆地东部奥陶系风化壳储层岩石类型可归纳为白云岩类、次生灰岩类、石灰岩类、云化灰岩类等四大成因组合。古岩溶地貌不同,则与储层的岩性效应不同,石灰岩及云化灰岩类是斜坡台地及残丘和盆地残台及残丘发育的标志性岩类;白云岩及次生灰岩类则是斜坡台缘、斜坡阶坪及盆地洼地发育的基础岩类。古岩溶地貌不同,则与储层的物性效应不同,斜坡台缘效应最好,斜坡阶坪中等,斜坡台地及残丘中下,盆地残台及残丘较差,盆地洼地最差。斜坡台缘与斜坡阶坪分界为盆地东部古岩溶效应的重要转折点,居其两侧的小层渗透率随古岩溶地貌的变迁而逆向增减,发育红色和蓝色2种不同的效应模式。小层物性效应则与白云岩类和次生灰岩类的含量密切相关,其效应模式呈现出此消彼长同时又互为补充的特点。如果储层岩类组成过于单一、或者某类组分含量过低或过高,都将对古岩溶地貌发育产生重要的影响;适度比率的岩类组合或者混合岩化对古岩溶储层的物性效应更为有利。
Taking the Ordovician weathering crust in the eastern part of Ordos Basin as an example, based on a large number of geological logging and experimental analysis data, the karst effects of paleokarst and paleokarst reservoirs were comprehensively analyzed according to the lithology and physical properties of ancient karst reservoirs feature. The results show that the rock types of the Ordovician weathering crust reservoir in the east of the basin can be classified into four major genesis combinations: dolomite, secondary limestone, limestone and limestone. Different ancient karst landforms have different lithology effects with the reservoir rocks. Limestone and limestone limestone are the symbolic rocks for the development of the stumps and remnant mounds in the slope lands and remnant mounds and basins. The dolostones and secondary limestone It is the basement rock of slope platform, slope terrace and basin depression. Paleo-karst topography is different from the physical property of reservoirs. The effect of the slope edge is the best. The slope slope is middle level, the slope terrace and the residual hill are middle and lower, and the basin residual station and residual hill are worse, and the basin depression is the worst. The boundary between the slope margin and the slope terrace is an important turning point of the paleokarst effect in the east of the basin. The permeability of small reservoirs on both sides increases or decreases inversely with the change of paleokarst geomorphology, and develops two different modes of red and blue effect. The physical properties of small layers are closely related to the content of dolomite and secondary limestone, and their effect patterns show the characteristics of shifting from one another to complement each other. If the composition of reservoir rocks is too single, or the content of some kinds of components is too low or too high, it will have an important influence on the development of ancient karst landforms. The moderate ratio of lithic assemblages or mixed rock sets have great influence on the physical properties of paleokarst reservoirs The effect is more favorable.