西湖凹陷D构造花港组储层成岩环境的变化对物性的影响

花港组储层作为西湖凹陷的主要油气储层之一,其储集岩主要为长石岩屑砂岩和岩屑长石砂岩,少部分长石石英砂岩和岩屑石英砂岩,具有中—低孔、低—特低渗特征。通过岩石薄片鉴定(431块)、扫描电镜(20块)、薄片粒度(106块)、地层水分析(8块)和黏土矿物X衍射(78块)等资料分析认为,成岩环境在影响了水岩反应及次生孔隙的发育。花港组上部(2 500~3 300 m)以酸性成岩环境为主,以长石溶蚀形成自生高岭石、石英次生加大和次生溶孔为特征;花港组下部(3 300~4 000 m)以碱性还原环境为主,菱铁矿等碳酸盐胶结物的大量出现,高岭石转化为伊利石、绿泥石,是造成孔隙度,特别是渗透率降低的主要原因。

9 SCHERER M.Parameters influencing porosity in sandstone:a model for sandstone porosity prediction[J].The AAPG Bullitin,1987,71(5):485-491.

HuagangSFormation is one of the main oil-gasSreservoirs in Xihu depression.These reservoir rocksSare mainlySfeldspar-lithic sandstone and lithic-feldspar sandstone,Sa fewSfeldspar-quartz sandstoneSand lithic-quartz sandstone,Swith medium-low porosity,Slow-extra low permeability. The diagenetic environment results in different water-rock reaction and development of secondary porosity by according toSthin-section identification,Sscanning electron microscopy , grain size analysiscast , formation water salinity and X ray diffraction.Upper Huagang group (2500m~3300m) in acidic diagenetic environment,theSfeldspar corrosionSformedSauthigenic kaolinite,Skiesel Sand dissolved pore.Lower Huagang groupSS(3300m~4000m)SinSalkaline environment,these emergences of a large number of carbonate cementation, kaolinite into illite and chlorite,are caused bySporosity,Sespecially permeability reduction