琼东南盆地松涛凸起低阻油藏特征及储层下限

综合利用常规测井、核磁共振测井、电阻率成像测井及地层测试数据，并结合岩芯实验分析结果对琼东南盆地松涛凸起区低阻油藏的储层特征进行精细表征，从宏观及微观等多方面深入分析了低阻油藏的成因及主控因素并定量确定低阻油藏的储层下限。结果表明，低阻油藏岩性以细砂岩为主，含少量粉砂岩、泥质粉砂岩及生屑砂岩，孔隙度及渗透率值变化较大，电阻率增大系数<1.5。研究区沉积环境主要为滨岸相环境，细粒物质含量偏高，较小的粒间孔隙及较差的孔隙结构造成地层中束缚水含量偏高，是造成研究区储层电阻率偏低的重要因素，泥浆侵入、导电矿物及黏土矿物附加导电性等对储层电阻率影响较小。在此基础上对低阻油藏储层下限进行了定量分析，确定了研究区低阻油藏储层孔喉半径、孔隙度、渗透率、电阻率、含油饱和度及泥质含量的下限值。此研究为琼东南盆地松涛凸起区低阻油藏的识别及勘探评价提供了理论基础，加速了研究区低阻油藏的开发进程。

Reservoir characteristics and cutoffs of low resistivity reservoir in Songtao Uplift,Qiongdongnan Basin

To finely characterize reservoir property, understand the genesis and main controlling factors, and quantitatively determine the cutoffs of low-resistivity reservoir in Songtao Uplift of the Qiongdongnan Basin in South China Sea, conventional logging, nuclear magnetic resonance logging, resistivity imaging logging, and formation testing data, as well as the core data were analyzed. Results show that the lithology of the low-resistivity reservoir is mainly fine-grained sandstone, including siltstone, argillaceous siltstone, and bioclastic sandstone. The porosity and permeability vary greatly, and the resistivity increase factor is less than 1.5. The sedimentary environment was sea shore, featuring fine-grained materials that have poor pore structure and pore connectivity. This feature resulted in the high content of pore irreducible water and capillary irreducible water in the sedimentary rock, which is the key reason for the low-resistivity oil reservoir, while mud invasion, conductive minerals, and additional conductivity of clay minerals had little effect on the reservoir resistivity. Therefore, the reservoir cutoffs were analyzed and determined quantitatively, including pore radius, porosity, permeability, resistivity, oil saturation, and clay content. This study paved road for identification and evaluation of low-contrast reservoir and will accelerate the development of low-resistance reservoirs in the study area.