东营凹陷盐家地区沙四上亚段砂砾岩储层岩相与物性关系

依据岩性、粒度、沉积构造等特征,将东营凹陷盐家地区沙四上亚段近岸水下扇砂砾岩体划分为10种岩相类型和13种在一次沉积事件中形成的岩相组合类型,并将其岩相组合类型划分为3大类6小类。针对砂砾岩储层在任一深度物性范围变化较大的问题,遵循"岩相组合类型-岩相类型-距砂泥接触面距离"的研究思路,采用逐步分解的方法,建立"岩相组合类型-岩相类型-距砂泥接触面距离"约束下的物性纵向演化图,结果显示任一深度物性参数变化范围相对较小,各岩相类型储层孔隙度的变化一般为±2%,渗透率的变化一般在一个数量级以内。对比分析各岩相类型物性图可知:随埋深增加,各岩相类型远泥岩部位储层物性整体变差;同一深度,由Ⅰ型岩相类型到Ⅱ型岩相类型物性变好。与远泥岩的各岩相组合底部岩相类型相比,扇中比扇根部位各级别孔隙度和渗透率的深度上限增加了800~1 200 m;与远泥岩的各岩相组合中上部岩相类型相比,扇中比扇根部位各级别孔隙度和渗透率的深度上限增加了1 100~1 650 m。扇中近泥岩部位和扇缘薄层砂因发生强烈胶结作用而使物性变差,在3 400 m以下基本为超低孔超低渗储层。

Relationship Between Lithofacies and Physical Properties of Sandy Conglomerate Reservoirs of Es 4s in Yanjia Area,Dongying Depression

According to the characteristics of lithology, particle size as well as sedimentary structure,the sandy conglomerate bodies are divided into 10 types of lithofacies as well as 13 types of lithofacies assemblages; each of which is of the same event deposits of Es 4s in Yanjia Dongying depression.The types of lithofacies assemblages are further divided into three categories and six subcategories.The scientific issue is that the range of the physical parameters of the sandy conglomerate reservoirs are relatively large at an arbitrary depth.Following the thought of “types of lithofacies assemblages-types of lithofacies-distance from sand-mud boundary”,and decomposing the lithofacies step by step,we achieved the charts of longitudinal physical property evolution which are restrained within each group of the lithoface division.Within each group of the lithofacies,the range of physical parameters of the lithoface is relatively small at an arbitrary depth:the range of porosity is ±2%;while the range of permeability is in one order of magnitude.When the lithofacies are far away from the mudstone,their physical property becomes weak with the increase of the burial depth.The physical property of type Ⅱ lithofacies is better than those of type Ⅰ lithofacies at the same depth.Compared to the lithoface types, which are at the bottom of lithoface assemblages far away from mud, the corresponding depth-upper-limit of different grades of porosity and permeability of the lithofacies types of the middle fan is 800 1 200 m deeper than that of the inner fan.Compared to lithofacies types which are at the middle-upper part of lithofacies assemblages far away from mud,the corresponding depth-upper-limit of different grades of porosity and permeability of the lithofacies types of the middle fan is 1 100 1 650 m deeper than that of the inner fan.The sandstones near mudstones in middle fan and thin sandstones in outer fan both have weak physical properties because of their intensive cementation.They are ultra-low porosity and ultra-low permeability reservoirs under the depth of 3 400 m.