低渗透储层“四性”关系综合研究——以二连盆地吉尔嘎朗图凹陷为例

Integrated study of four-property relationship of low permeability reservoir: case study of Jirgalangtu depression, Erlian basin

（1.成都理工大学“油气藏地质及开发工程”国家重点实验室，四川成都610059；2.中国石油勘探开发研究院西北分院，甘肃兰州730020）

Institute of Sedimentary and Geology, Chengdu University of Technology, Chengdu 610059, China

吉尔嘎朗图凹陷是二连断陷盆地的重点勘探凹陷之一，储集层主要为以近源的扇三角洲、近岸水下扇和湖底扇沉积为主的砂砾岩体，油藏类型以岩性、构造-岩性油气藏为主，含有高电阻水层和低电阻油气层。通过对该地区钻井、录井、测井、试油和岩心分析等资料的综合分析研究，总结出该地区中孔、低渗油气层的“四性”关系，建立了测井解释模型，确定出油层的有效厚度下限标准。在此基础上，利用三孔隙度重叠法有效地判断出低电阻气层；利用自然电位异常幅度有效地判断出高电阻水层和低电阻油气层。对该地区所有老井进行了复查，将X4井区X4-12井Ⅰ号层(原水层)解释为油层,使得Ⅰ号层连成一片，扩大了含油面积。此外，X4井区有5层4.7m厚的致密层被解释为差油层，有17层23.8m厚的差油层被解释为油层，增加了所发现的油层厚度。

Jirgalangtu depression is one of the important exploration targets in Erlian faulted basin. The reservoirs are mainly glutenite bodies of fan delta, near-shore sub-aqueous fan and sublacustrine fan deposit. The reservoirs are mainly of lithologic and structurallithologic reservoirs characterized by high resistivity water layers and low resistivity gas layers. Based on the analysis of well drilling, mud logging, well logging, testing and core analysis, the relationship among four properties of medium porosity and low permeability reservoir was discussed. According to the relationship, the well logging interpretation model was established and the standard lower limit for the effective thickness determined. On this basis, we used the threeporosity overlay method to effectively identify the low resistivity gas layers. The abnormal magnitude on spontaneous potential was used to effectively recognize high resistivity water layers and low resistivity gas layers. The old wells are rechecked and the layer No.1 (water layer formerly) in X4-12 well area was interpreted as oil, making the layer No.1 become a whole and the oilbearing area broadened. Moreover, five tight layers (4.7 m) in X4 well area were interpreted as poor oil layer, seventeen poor oil layers were interpreted as oil layers, largely increasing the thickness of oillayer.