冲积扇相储层沉积微相分析——以吐哈盆地鄯勒油气田第三系气藏为例

SEDIMENTARY FACIES OF THE FORTH SUB-MEMBER OF THE SHANSHAN FORMATION AT SHANLE OIL AND GAS FIELD IN TUHA BASIN

在岩芯观察的基础上,综合运用地质、测井和地震资料,从单井相分析入手,并通过连井对比将剖面扩大到全区范围,详细研究了吐哈鄯勒油气田第三系气藏储层的沉积微相类型,重点分析了主要产气层的沉积微相平面展布特征。认为本区第三系鄯善群属冲积扇扇中亚相沉积,主要微相类型是辫状水道和漫溢(可见扇中泥石流和辫流砂岛)。通过分析测试发现,天然气主要分布于扇中辫状水道中,其次是漫溢微相,因此,在研究区储层埋藏浅和年代新的情况下,天然气优先进入砂层厚度相对大和储集物性相对好的扇中内侧前缘辫状水道微相砂体中。

By using the geological, log and seismic data,the types of the micro-facies of the Shanshan formation in Shale oil and gas field in Tuha basin were studied, and the distribution of the micro-facies of the forth sub-member was analyzed. The results show that the Shanshan formation belongs to the middle fan of alluvial fan deposits, which can be further divided into 4 sub-faciese, including braided channel, overbank deposits, debris flow and braided bar. The former two are the main sub-faciese. The analysis of the well testing data shows that natural gas is mainly dispersed in the micro-facies of braided channel, secondly in overbank deposits and in braided bars. In the background of being shallow-burried and in relatively young strata, the gas accumulation favorably occurs in the sand bodies of the braided channel micro-facies.