Abstract: The lower cretaceous oil-bearing reservoir of Hailar-Tamtsag basin is composed of several NNE trending volcanic rift basin group during the early cretaceous. In the early phase, large-scale volcanic debris flow sediment filled in the lacustrine basin center where the source was prolific, which then caused the formation of endogenous volcanic debris flow oil and gas reservoirs that became a new and major reservoir type in the basin. The petrology experiments suggest that the combination of lithology in this reservoir is different from the usual pyroclastic rock such as “tuffaceous sandstone” and “tuff glutenite”. Its mixed facies are caused by rapid accumulation of volcanic debris flow with specific sedimentary origin and paleogeographic environment, which is also a new type of reservoir sedimentary origin on which there is less domestic and international research. The characteristics of this reservoir includes mélange accumulation of tuff and normal glutenite, complex types of pore space, strong water-sensitivity, low permeability, fast change of facies, strong heterogeneity. Since the reservoir is a special type of reservoir with unstable physics and chemistry, it has strong sensibilities and weak cementation, which likely causes strong water-sensitivity, speed-sensitivity, casing damages and deformations, sand productions, and the development is difficult. The investigation of the genetic mechanism of volcanic debris flow reservoir will provide the theoretical basis for optimizing the development method, making rational policy and exploiting economically and effectively.

Key words: volcanic debris flow, Hailar-Tamtsag basin, chaotic lithology, strong water-sensitivity, low permeability

摘要： 海拉尔-塔木察格盆地早白垩世由若干个北东向展布的含火山断陷盆地成群排列组成。早期大量的火山物质充填在盆地箕状断陷湖盆中心,形成内源型火山泥石流油气藏,成为一种新的而且是该盆地主要的油气储集类型。通过大量的岩石学观察研究, 表明盆地内储层岩性组合不同于通常火山碎屑岩中的“凝灰质砂岩”或“凝灰质砂砾岩”,而是火山泥石流快速堆积的混杂岩相,有其特殊的储层沉积成因和特定的古地理环境,属于一种研究程度较低的新型沉积成因储层类型。该种储层类型具有凝灰岩与正常砂砾岩混杂堆积、岩性复杂、分选差、孔隙类型复杂多样、渗透率低、非均质性强等特点。储层物理、化学性质不稳定,敏感性强,胶结作用弱,常规注水开采容易造成水敏、速敏、套损、套变和出砂严重等问题,开发难度大。探讨了火山泥石流储层成因机理,可为优选开发方案、制定合理的开发技术政策、获得经济有效开发提供理论依据。

关键词: 火山泥石流, 海拉尔-塔木察格盆地, 混杂岩性, 强水敏, 低渗透