三塘湖盆地马朗凹陷哈尔加乌组致密凝灰岩储集层特征

Characteristics of Dense Tuff Reservoir of Haerjiawu Formation in Malang Sag in Santanghu Basin

三塘湖盆地马朗凹陷哈尔加乌组发育多种岩性,利用测井交会图版,可以很好地识别出玻屑凝灰岩、晶屑玻屑凝灰岩和岩屑玻屑凝灰岩3种类型。平面上,马朗凹陷哈尔加乌组沉积中心多为玻屑凝灰岩和晶屑玻屑凝灰岩,向沉积边缘岩屑含量增多,逐步过渡到火山岩。储集空间可分为原生孔隙、次生孔隙和裂缝3大类,其中原生孔隙中的晶间孔和次生孔隙中的溶蚀孔是主要的储集空间,微裂缝可以有效提高局部储集层渗流性能。玻屑凝灰岩和晶屑玻屑凝灰岩物性较好,但玻屑凝灰岩分布较局限;岩屑玻屑凝灰岩物性较差。哈尔加乌组致密凝灰岩油藏,其形成主要受成熟烃源岩展布与有利凝灰岩储集层分布共同控制,位于M2井—M15井区块的互层型凝灰岩具有良好的源储共生关系,是最有利的勘探区带。

The Haerjiawu formation in Malang sag in Santanghu basin is of variety of lithologies. Using logging crossplots can well identify its three types of lithologies such as vitric tuff, crystal-vitric tuff and lithic-vitric tuff. In plane, the sedimentary center of Haerjiawu formation is dominated by vitric tuff and crystal tuff, and toward sedimentary edge, the lithic content is increased and then transitional to volcanic rock. The reservoir space mainly includes primary pores, secondary pores and fractures, among which the intercrystalline pore in primary pores and dissolution pore in secondary pores are the main reservoir spaces, and micro-fracture can effectively improve the local reservoir＇s percolation. The study shows that the vitric and crystal-vitric tuffs contain good physical property, but the vitric tuff is in limited distribution, and the lithic-vitric tuff is poor. The formation of Haerjiawu dense tuff reservoir is mostly controlled by mature source rock and favorable tuff reservoir distributions. The interbedded tuff in M2-M15 well block has a good relationship of source-reservoir coexistence and could be the most favorable zone for petroleum exploration.