鄂尔多斯盆地华池地区长6油层组重力流特征及控制因素

Characteristics of gravity flow and controlling factors of Chang 6 oil reservoir set in Huachi area, Ordos Basin

以岩心观察为基础,通过岩石学特征和原生沉积构造等相标志分析,认为华池地区长6油层组主要包括砂质碎屑流和浊流2种重力流沉积,但二者发育位置存在差异。其中,砂质碎屑流位于上游,浊流位于下游。砂质碎屑流和浊流在沉积上的差异,决定了其储层特征的差异,相对于浊流砂体,砂质碎屑流砂体成分成熟度更低,填隙物含量更低,储层物性更好和含油性更好。华池地区长6油层组储层中填隙物类型主要为伊利石、钙质和绿泥石膜,砂质碎屑流砂体中伊利石和钙质含量较高,浊流砂体中绿泥石膜含量较高。华池地区长6油层组储层主要储集空间为原生粒间孔和粒内溶孔,而且砂质碎屑流砂体的面孔率明显高于浊流砂体。砂质碎屑流砂体中长石含量较高,为溶蚀作用提供了更多的物质基础,因此砂质碎屑流砂体中的粒内溶孔较浊流砂体发育,这是该砂体储层物性好于浊流砂体的重要原因。

Based on core observation, this paper analyzed the petrology characteristics and primary sedimentary structure and other sedimentary facies symbols, and concluded that the gravity current sedimentation of Chang 6 oil reservoir set in Huachi area is mainly consist of sandy debris flow and turbidity current sedimentation. These two kinds of gravity current sedimentation stay quite different in their growing location. Sandy debris flow locates in upstream, while turbidity current sedimentation stays in downstairs. This difference leads to the zonation in reservoir characteristics between south and north. Sandy debris flow has lower compositional maturity and interstitial fillings but better reservoir physical properties and oiliness, while turbidity current sandstone reservoir performs by contraries. The types of interstitial fillings of reservoir sand body of Chang 6 oil reservoir set in Huachi area are mostly illite, calcareous cementitious and chlorite film. Sandy debris flow has higher contents of illite and calcareous eementitious, but turbidity sand body possesses higher contents of chlorite film. The main reservoir space of Chang 6 oil reservoir set in Huachi area is primary intergranular pores and intragranular dissolved pores. The surface porosity of sandy debris flood is apparently higher than that of turbidity sand body. The feldspar which consists more sandy debris flood provides more physical foundation of dissolution, thus the content of intragranular dissolved pores in sandy debris flowsand body is larger than that of turbidity sand body.