X-CT扫描成像技术在致密砂岩微观孔隙结构表征中的应用——以大安油田扶余油层为例

以松辽盆地南部大安油田扶余油层致密砂岩样品为研究对象,利用VGStudio MAX强大的CT数据分析功能结合Avizo软件先进的数学算法,建立了大安油田扶余油层致密砂岩多尺度三维数字岩心模型,该模型具有样品无损、结果直观、数据丰富等优势;同时结合环境描电镜(ESEM)、Maps图像拼接技术、铸体薄片、恒速压汞等油气分析测试方法对松辽盆地南部大安油田扶余油层微观孔隙特征进行了定量表征,为进一步开展大安油田扶余油层渗流机理的研究打下了基础。研究表明:微米尺度下,大安油田扶余油层储集空间类型以溶蚀型孔隙和微裂缝为主,不同孔渗的样品孔喉的形态和尺寸有所不同,孔喉形态多为球状和条带状,孔喉分布状态主要有连片状和孤立状两种;纳米尺度下,大安油田扶余油层储集空间类型以矿物颗粒内部或表面的溶蚀孔隙和微裂缝为主,纳米孔喉形态上多呈小球状、管状,微裂缝对纳米级孔隙有很好的沟通作用。喉道半径较窄是造成样品的实测渗透率较低的主要原因。

Application of X-CT Scanning Technique in the Characterization of Micro Pore Structure of Tight Sandstone Reservoir: an Example from Fuyu Oil Layer in Daan Oilfield

The tight sandstone samples from Fuyu oil layer in Daan oilfield of Songliao basin were studied .In order to further study on the mechanism of seepage ,a 3D digital core model with real pore throat structure was constructed by combining VGStudio MAX with Avizo ,which has the advantages of non‐destructive to samples ,visualized results ,and abundant data .Combining with ESEM Maps image splicing technology ,the casting thin sections ,and a constant speed mercury penetration analysis ,the micro pore structure quantitative characterization of Daan oilfield was studied in Fuyu oil layer in the southern Songliao basin .The research showed that at micro‐scale ,the reservoir space types are mainly dissolution pores and micro cracks ,the samples of different porosity and permeability have different pore throat size .The pore structure morphology is characterized by the two main forms of globular and stripped ,and their pore throat distribution are two forms of contiguous and isolated ;at nanoscale , reservoir space types are dissolution pores with mineral particles inside or on the surface and micro cracks ,the pore throat morphology is characterised by the two forms of small globular and tubular ,and the micro cracks have very good connection with nanoscale pore .Narrow throat radius is the main cause of low permeability of the samples .