258 / 2022-03-30 23:02:55

玛瑚南斜坡区A井区四性关系及有效厚度下限研究

玛瑚南斜坡区 四性关系 有效厚度下限 钙质砂岩

摘 要  为提高玛湖南斜坡区A井区目的层段测井解释及有利区域预测的精度，本研究基于岩心、测井、分析化验资料、试油及地震反演等基础资料，井震结合，通过测井曲线解释、“四性”关系研究、油层有效厚度下限标准的确定，进行了小层细分、油层及钙质隔夹层识别。研究表明：（1）目的层根据SP与GR测井曲线划分为2个小层。第一小层渗透性砂体发育，以细砂岩为主，第二小层以非渗透性砂体为主。（2）目的层段主要岩性为细砂岩，其次有粉砂岩、泥质粉砂岩、泥岩及钙质砂岩。储层岩性以细砂岩为主，属压嵌型胶结，胶结物以高岭石为主，其次是伊蒙混层。储集空间类型以原生孔隙为主,占比80%，属于中孔、低渗储层。（3）第一小层多为复合水下分流河道，局部发育泥岩或钙质砂岩薄夹层。（4）通过绘制油层识别图版，综合确定A井区目的层有效厚度下限为：DEN≤2.35g/cm³，Rt≥4.4Ω.m，Φ≥19.0%，So≥40.0%。属低阻油层，储层主要发育于第一小层。（5）第一小层钙质隔夹层发育，平均厚度在0.97m，测井响应特征表现为低自然伽马值、高密度、高电阻率，电阻率陡增，多发育在复合水道形成的两套砂体底部。底部砂体比上部砂体厚，物性好，且钙质隔夹层对流体的向上运移起到阻碍作用，导致下部砂体油气相对富集。

关键词  玛瑚南斜坡区  四性关系  有效厚度下限  钙质砂岩

Abstract In order to improve the accuracy of log interpretation and favorable region prediction of target horizon of A well area in Mahu south slope area, the study has carried out the subdivision of thin layers and the identification of oil layers and calcareous interlayer by using the methods of logging curve interpretation, the study of four-property relationship, the determination of the lower limit of oil layer effective thickness and well seismic combination. The results show that：(1) The target horizon is divided into two sub layers according to SP and GR logging curves. The first thin layer is mainly permeable sand body, while the second thin layer is mainly impermeable sand body. (2) The main lithology of the target horizon is fine sandstone, followed by siltstone, muddy siltstone,mudstone and calcareous sandstone. The reservoir lithology is mainly fine sandstone, and the cementation type belongs to pressure inlay type. The cement is mainly kaolinite, followed by montmorillonite. The reservoir space type is mainly primary porosity, accounting for 80%,.The reservoir belongs to medium porosity and low permeability reservoir.(3)The first thin layer is mostly a composite underwater distributary channel, with interlayer of mudstone or calcareous sandstone developed locally.(4)By drawing the oil layer identification chart, it is comprehensively determined that the lower limit of the effective thickness of the target horizon of A well area is：DEN ≤ 2.35g/cm3, RT ≥ 4.4 Ω m， Φ ≥19.0%，So≥40.0%. The study area belongs to low resistivity oil layer, which is mainly developed in the first thin layer. (5) The first thin layer of calcareous interlayer is developed, with an average thickness of 0.97m. The logging response is characterized by low natural gamma value, high density and high resistivity values. It is mostly developed at the bottom of two sets of sand bodies formed by channel complex. the relative enrichment of oil and gas in the bottom sand body is due to the thicker thickness of the bottom sand body and the barrier effect of calcareous interlayer.

Key words  Mahu south slope area ，four-property relationship ，lower limit of effective thickness，calcareous interlayer