鄂尔多斯盆地山城-演武地区三叠系延长组长6-长8低渗储层特征及成岩作用研究

LOW PERMEABLE SANDSTONE RESERVOIR CHARACTERISTICS AND DIAGENESIS OF CHANG 6,CHANG 7 AND CHANG 8 FORMATION OF THE YANCHANG FORMATION(TRIASSIC),SHANCHENG-YANWU AREA,ORDOS BASIN

鄂尔多斯盆地山城-演武地区三叠系延长组长6-长8段砂岩属于典型的低孔低渗储集岩,具有粒度细、成分成熟度低、磨圆度差、分选中等等特征。通过薄片、X射线衍射、扫描电镜、压汞、阴极发光等分析手段,研究了延长组长6-长8段砂岩储层的特征、成岩阶段及演化模式,分析了低渗储层物性的影响因素,指出沉积相带是影响储层储集性能的地质基础,机械压实作用和晚期的铁方解石胶结作用是影响低渗透砂岩储层形成的主要因素,绿泥石包膜、溶蚀作用及微裂缝对储层储集性能的改善起到了积极作用。

Reservoir sandstone of Chang 6, Chang 7 and Chang 8 formation of the Yanchang formation （Triassic） in Shancheng-Yanwu area of Ordos basin is typical of low porosity and low permeability, which has the characteristics of fine grain size, low composition maturity, poor roundness and middling sorting. Based on thin-section observation, X-ray diffraction, SEM, mercury injection and cathodolum inescence techniques, this article takes research on reservoir sandstone characteristics, diagenetic stage and diagenetlc mode in Member 6 to 8 of Yanchang formation, analyses their influence on low permeability reservoir physical property. Meanwhile, the article indicates that mechanical compaction at the early diagenesis phase and ferroan calcite cementation at the late dlagenesis phase are main factors making them very low permeable, chlorite rim, grain dissolution and micro-fracture are believed to have improved the reservoir quality.