陕北地区延长组长6 1段油水层识别及含油性评价

Identification of Oil-Water Layers and Their Oil-Bearing Property Evaluation of Yanchang Formation Chang 61 Member in Northern Shaanxi

陕北地区三叠系延长组长6 1段是石油勘探开发的重要层位，该段普遍发育高自然伽马砂岩，该类储层和常规储层测井响应特征不同，这使得陕北地区延长组长61段储层电性、物性变化复杂，给储层测井评价带来很大困难，本文提出在分区域、分储层类别基础上建立测井解释图版，该解释图版油、水层点的分布规律较为明显，可以进一步应用到实际的测井解释中。高伽马储层岩心分析饱和度与邻近常规储层相差不明显．但是．由于高伽马储层电阻率数值下降明显，造成高伽马储层与邻近常规储层利用测井资料计算出来的含水饱和度相差较大．因此，有必要对高伽马储层饱和度计算公式进行修正。本文在储层分类基础上，分析了陕北地区延长组长6 1段储层饱和度测井计算的影响因素，建立了该地区长6 1段复杂储层含水饱和度计算公式。

As important horizons tor petroleum exploration and development, there was high natural gamma-value sandstone developed widely in the Chang61 Member of Triassic Yanchang Formation in Northern Shaanxi. The well logging response characteristics of these reservoirs are different from those of conventional reservoirs. This makes the electrical and petrophysical properties of tire northern Shaanxi Yanchang Chang61 reservoirs varied intricately. It brings big difficulty to the well logging evaluation of the reservoirs. The paper puts forward that a well-logging interpretation chart is set up on the basis of different regions and reservoir classification. On this chart, the distribution of oil/water layer points is obvious, and can be further applied to the actual well logging interpretation. The differenees between the saturation from core analysis of high gamma-value reservoirs and that of neighboring conventional reservoirs are not ob,Aous. However. differences between water saturation calculated by the log data from high gamma-value reservoirs and neighboring conventional reservoirs are large due to the significant decrease of resistivity values of high gamma-value reservoirs. Therelore. it＇s necessary to modify. （revise） the calculation formula of water saturation of high gamma-value reservoirs. The factors affecting Northern Sbaanxi Chang61 reservoirs water-saturation calculations from well-logging data are analyzed in this paper. on the basis of the reservoir classification. The calculation lormula of water saturation of complex reservoirs of Chang61 Member in the region is established.