松辽盆地徐家围子断陷深层火山岩储层特征及有利区预测

松辽盆地徐家围子断陷火山岩可划分为火山熔岩和火山碎屑岩两类,火山岩储层的有效储集空间包括孔隙和裂缝两种类型。裂缝不仅为储集空间,还可连通各种孔隙并促进后期溶解作用。在识别裂缝类型的基础上,建立了裂缝孔隙度计算模型,根据12口井的测井解释结果,按裂缝孔隙度将火山岩储集层分为3级:Ⅰ级,孔隙度大于0.5%;Ⅱ级,孔隙度为0.2%～0.5%,Ⅲ级,孔隙度小于0.2%。火山岩相可划分为边缘亚相、过渡亚相和中心亚相,其中,中心亚相位于火山通道附近,发育构造裂缝和收缩缝,储集物性较好,是最有利的储集相带;过渡亚相的裂缝比较发育,储集物性中等,为有利储集相带;而边缘亚相储集物性差,为不利储集相带。

Reservoir characteristics of deep volcanic rocks and prediction of favorable areas in Xujiaweizi fault depression in Songliao basin

Volcanic rocks in Xujiaweizi fault depression in Songliao basin can be classified into lava and vocaniclastic rocks.The effective reservoir spaces of volcanic reservoirs are pores and fissures. Fissures can not only act as reservoir spaces, but can also interconnect pores of different types and promote dissolution at later stages. A computation model of fissure porosity is developed based on recognition of fissure types. According to logging interpretation of 12wells, the volcanic reservoirs are divided into 3 grades based on their fracture porosity,i.e.grade Ⅰ with porosity above 0.5%, grade Ⅱwith porosity ranging from 0.2% to 0.5%, and grade Ⅲ with porosity below 0.2%. Volcanic rock facies can be subdivided into marginal, transitional and central subfacies. The central subfacies, located near volcanic conduit, has well developed structural and contraction fissures and relatively good poroperm characteristics,so it would be the most favorable reservoir facies belt; the transitional subfacies, having relatively well developed fissures and moderate poroperm characteristics,would be a favorable reservoir facies belt; while the marginal subfacies has poor poroperm characteristics,it would be an unfavorable reservoir facies belt.