中文摘要：

鄂尔多斯盆地镇泾区块长8致密砂岩储层普遍发育钙质夹层,本文利用露头、岩芯、薄片及测井等资料,对钙质夹层的岩性特征、电性特征、分布规律以及与天然裂缝分布的关系进行了研究。研究表明,钙质夹层具有明显的低伽马、低声波时差、高密度、高感应的特点,电成像测井表现为明显的亮色条带。钙质夹层主要分布在部分水下分流河道砂体的中部或下部及河口坝砂体的中部或上部,同时也发育在一些分选较好、颗粒支撑的薄层细砂岩中以及砂泥岩的接触地带。钙质夹层内主要发育高角度构造裂缝,不发育近水平成岩裂缝;与非钙质胶结致密砂岩储层相比,钙质夹层脆性较大,天然裂缝更为发育,且大部分裂缝被方解石充填,为无效裂缝;钙质夹层层厚及岩性界面控制着裂缝纵向延伸高度。论文成果对进一步研究致密储层天然裂缝的分布模式,弄清裂缝对注水开发的影响具有重要意义。

英文摘要：

Calcareous interbeds develop widely in Chang 8 tight sandstone reservoirs, Zhenjing Area, Ordos Basin. This paper reported the lithology, electricity, distributing characteristies of the calcareous interbed and the relationship with the distribution of natural fractures based on outcrops, cores and logs data. Studies have shown that calcareous iuterbeds have the following electrical character/sties. Natural gamma ray log is low. Longitudinal wave offset and transverse wave offset time are also low. The value of density logging is high and induction logging is obvious high. Electric imaging logging has the characteristic of clear light yellow （light）. Good development of calcareous interbeds presents at the middle or bottom of underwater distributary channel sand body and at the top or middle of mouth bar sand body in delta front. Besides, calcareous interbeds are distributed in well-sorted, grain supported fine sandstones and contact zones of mudstones and sandstones. There are mainly high angle tectonic fractures in calcareous interbeds with little nearly horizontal diagenetic fractures. Calcareous interbeds are brittler than non-calcareous cementation tight sandstone. In consequence there are more natural fractures and the majority of them are filled with calcite taken as invalid. The thickness and lithologic interface of calcareous inerbeds determine the longitudinal height of fractures. All the achievements of this thesis are significant to study the distribution patterns of natural fractures and the effect of fractures on water flooding development.