岩性-电性交会方法在疏松砂岩气藏水侵研究中的应用——以柴达木盆地台南气田为例

柴达木盆地台南气田是典型的疏松砂岩气藏,具有岩层疏松、砂泥岩互层、边水环绕、气水分布复杂等特殊地质特征,气藏开发中后期,水侵后地层电阻率变化特征不明显,储集层流体识别困难。从测井资料标准化处理入手,在国内外水侵测井解释技术的基础上,充分运用岩电关系进行水侵机理研究。利用常规和生产测井资料中的电性曲线对水侵层进行定性识别,并提出一种基于岩性—电性交会的水侵特征识别方法,建立水侵层的参数定量识别、层位标定,形成一套较为完整的水侵评价技术,解决了低阻气层水侵识别难的问题。利用建立的测井水侵层解释模式和评价方法,对部分新钻开发井进行水侵层解释,符合率为84.2%,岩性—电性交会方法对于其他疏松砂岩气藏开展水侵层识别和解释具有借鉴意义。

Application of Lithology-Electrical Property Rendezvous Method in Studying Water Invasion in Unconsolidated Sandstone Gas Reservoirs:A Case Study from Tainan Gas Field,Qaidam Basin

Tainan gas field in Qaidam basin is a typical unconsolidated sandstone reservoir,which is characterized by loose stratum,sandstone interbedded with mudstone,surrounded by edge water and complex gas-water distribution.During the mid-late development period of gas reservoirs,the changes of formation resistivity are not obvious after edge water invasion,resulting in the difficulties of fluid identification in the reservoir.Based on the logging data normalization and logging interpretation technologies for water invasion,the lithology-electrical property relations are used to study water invasion mechanism.The electrical property curves obtained from conventional logging and production logging are used to identify water invasion zones qualitatively,a method to identify water invasion characteristic is proposed on the basis of lithology-electrical property rendezvous,quantitative parameter identification and horizon calibration are performed for water invasion zones,and a set of water invasion evaluation technologies has been established and the difficulties of water invasion identification in low-resistivity gas zones can be overcome.The established logging interpretation mode and evaluation method for water invasion zones are put into use in some newly-drilled wells and the interpretation coincidence rate is 84.2%,which proves that the lithology-electrical property rendezvous method can be the references for water invasion zone identification and interpretation in other unconsolidated gas reservoirs.