塔木察格盆地塔南凹陷南屯组储层特征

CHARACTERISTICS OF NANTUN-FORMATION RESERVOIRS IN TANAN SAG OF TAMUTSAG BASIN

南屯组是塔南凹陷下白垩统的主要勘探目的层之一.南屯组发育3套砂组,Ⅰ砂组的单层砂岩厚度大且空间分布稳定.岩石类型为岩屑长石砂岩、长石岩屑砂岩和岩屑砂岩.南屯组储层属于低孔、特低渗储层,连通粒间孔隙的喉道十分细小,岩石的排驱压力普遍偏大.南二段的储层物性优于南一段,影响储集性能的因素有沉积作用和成岩作用.沿次凹东侧同生控陷断裂呈北东向条带状分布的近源砂体是较好的储层,早期油充注的砂岩储层物性明显变好.

Nantun Formation is one of the main exploration target strata of Lower Cretaceous in Tanan Sag. There are three sets of sandstone groups of the formation, Sandstone Group I individual sandstone is pretty thicker and stably distributed in space. The rock types are divided into lithic arkose, feldspathic litharenite and lithic sand- stone. Nantun Formation reservoir is characterized by low porosity, extra/ultra -low permeability and very tiny pores and throats connecting the intergranular pores, so the expulsive pressure within the rocks is commonly on the high side. the physical properties of Member Nan-2 reservoir are much better than those of Member-1. The deposition and diagenesis are the influencing factors on the accumulating performances. The proximal sandbodies are devel- oped into much better reservoir, which are distributed linearly along NE-orientated syngenetic depression-controlling faults in the eastern boundaries of the subsags. The physical properties in the sandstone reservoirs become obviously favorite because the reservoirs have experienced early the filling of the crude oil.