大港枣园油田火山岩裂缝性储层特征及其控制因素

大港枣园火山岩裂缝性稠油油藏,储层的复杂性和非均质性是导致其开采难度大的关键因素。岩心、薄片、CT扫描、压汞、测井和生产动态等资料研究表明,枣园火山岩为玄武岩类,可细分为气孔玄武岩、致密玄武岩、火山角砾岩和凝灰岩;岩相可划分为溢流相和爆发相2个亚相和气孔玄武岩、致密玄武岩、凝灰岩、火山角砾岩等4个微相;储集空间类型多样,既有孔隙,又有气孔和裂缝,储集空间划分为3大类和12种类型,可以组合成5种储渗配置关系,并以裂缝-孔隙型和大孔大缝-小孔小缝复合型储集渗流模式为主要的储渗模式。根据岩性、缝洞发育程度、物性高低和储量大小,本文对基质和裂缝的有效性进行了评价和分类。构造作用和岩相是火山岩裂缝性储层发育的主要控制因素。

The Zaoyuan Oil Field, Dagang, Tianjin:Crack-type volcanic reservoirs and their controlling factors

The complexity and heterogeneity of crack-type volcanic reservoirs are considered to be key factors controlling the exploitation of the Zaoyuan Oil Field in Dagang,Tianjin.The data on boreholes,thin sections,CT scanning electron photomicrographs,mercury-injection method,well logs and production regimes show that the Zaoyuan volcanic rocks are assigned to basalts,which may be subdivided into vesicular basalt,dense basalt,volcanic breccias and tuff. The lithofacies may be subdivided into two subfacies including the flood and explosion subfacies,and four microfacies including the vesicular basalt,dense basalt,volcanic breccia and tuff microfacies.The reservoir spaces include three types and twelve subtypes,which may be grouped into five reservoir-permeability associations represented by the reservoir-permeability models for the crackporosity type and composite macropore-macrocrack and micropore-microcrack type.The assessment and classification are further made on the validity of the matrix and cracks on the basis of lithology,crack and pore space development,physical property and reserves.The main controlling factors for the cruck-type volcanic reservoirs include tectonism and lithofacies.