基于构型单元的储层质量分布模式——以胜坨油田二区沙二段8砂组厚层河口坝砂体为例

Distribution patterns of reservoir quality based on configuration unit of mouth bar sandbody: A case study from the 8^(th) sand group of the 2^(nd) member of the Shahejie Formation in Shenger Block of Shengtuo oilfield,East China

以取心井岩心、薄片、扫描电镜、测井资料及生产动态分析为基础,采用"垂向细分"、"侧向划界"以及"平面组合"的思路,针对胜坨油田二区厚层河口坝砂体,按复合河口坝、单一河口坝及单一河口坝内部增生体3个层次进行构型单元的逐级解剖,在此基础上探讨了基于构型单元的储层质量分布模式。研究结果表明,不同构型单元内部储层参数分布规律分异性较强。Ⅰ类和Ⅱ类储层主要分布于河口坝主体,Ⅲ类储层多分布在河口坝侧翼以及河口坝内部夹层的遮挡区,Ⅳ类储层则集中分布于席状砂。此外,结合生产动态数据等探讨了注水开发过程中不同构型单元内储层参数的动态变化特征。其中,储层孔隙度随注水开发的进行总体趋势是增大的,但变化幅度不大。坝主体孔隙度增幅最大,坝侧缘次之,席状砂基本不变。储层渗透率的趋势既有增大、又有减小。随注入水的不断冲洗,坝主体等高-特高渗储层有效渗透率升高,坝侧缘、水下分流河道等中-低渗储层渗透率降低,席状砂等低渗储层基本不变。储层孔隙度增加幅度较渗透率小得多。从低含水到特高含水阶段,不同构型单元的粒度中值都有所增大,泥质含量均降低。

Based on core,thin section,SEM,well logging data and performance analysis and guided by reservoir configu-ration theory,configuration analysis of thick mouth bar sandstone in the second block in Shengtuo oilfield was carried out at three levels including composite mouth bar,single mouth bar and internal accretion within single mouth bar.On this basis,reservoir quality distribution patterns of different configuration units were analyzed.Result indicates that reservoir parameters of different configuration units are significantly different.ClassⅠandⅡreservoirs mainly occur in the major parts of mouth bars.ClassⅢreservoir is generally distributed on flanks of mouth bar and under interlayers in the interior of mouth bars, while Class Ⅳ reservoirs mainly occur in sheet sands.In addition, dynamic characteristics of reservoir parameters in different configuration unit during waterflooding were discussed by using performance data.The reservoir porosity increased during waterflooding as a whole,but changed slightly.The largest increase appeared in the center of mouth bar,followed by bar flank,and nearly no changes occurred in sand sheet.In contrast,reservoir permeability showed different trends in different configuration units.Some units increased while others decreased.With constant flushing of injected water,effective permeability increased in high or ultra-high permeability reservoirs such as mouth bar center,＆amp;nbsp;decreased in middle or low permeability reservoirs like bar flanks and underwater distributary channels and remained unchanged in low-permeability sheet sand.The amplitude of porosity increase was much smaller than that of permeability. Median grain size of different configuration units all increased to some extent at both low and high water-cut stages,while clay content decreased.