赤水地区上三叠统须家河组沉积特征

STUDY ON SEDIMENTARY CHARACTERISTICS OF UPPER TRIASSIC XUJIAHE FORMATION IN CHISHUI AREA

根据露头和井下资料并结合四川盆地的区域沉积特征,分析和总结了赤水地区上三叠统须家河组(T3x)的地层和岩性特征,并据此推测了沉积环境和指明了油气勘探的方向。认为须家河组系泛滥平原组合中的河流沉积环境,发育辫状河和曲流河2种类型;沉积相属辫状河相与曲流河相,包括河床和河漫2个亚相类型,从中可识别出心滩、边滩、河漫滩、河漫洼地及沼泽等微相;但须家河组砂岩层段的储集条件并不理想,而泥岩和煤层又比较薄,故勘探目标应首选构造裂缝和断层发育的区块。

Based on outcrop and drilling data and considering of regional sedimentary characteristics,both stratigraphic and lithologic characteristics of Xujiahe formation (T_3x) in Chishui area are deeply analysised in this article. The sedimentary characteristics was summarized, then the sedimentary environment was speculated, what's more the petroleum prospect was pointed out. It has been made known that T_3x here belong to fluvial deposit, which devides the braided river and the meander river. The corresponding sedimentary facies are braided river and meander river facies,including two kinds of sub-facies which are stream bed and valley flat. The identified micro-facies involves channel bar, bar point and alluvial flat, valley depression and valley marsh. The prospect of T_3x should lie in the place where joints and faults are windly found, for its own reservoir and source conditions are limited.