超压砾岩油藏具有低孔高渗的异常特征,核磁共振测井渗透率计算的经典模型不能求准储层渗透率.通过深入分析超压储层特征和物性影响机理,明确了超压强度是渗透率的主控因素,提出了在SDR模型的基础上引入超压物性指数和孔隙结构指数,构建超压砾岩储层核磁共振渗透率处理模型的新方法.以准噶尔盆地玛湖凹陷二叠系上乌尔禾组为例,开展了超压砾岩油层岩石物理联测实验以模拟地层超压,研究了超压对储层孔隙度、渗透率及电阻率的影响,建立了超压砾岩储层的SDR-超压渗透率计算模型.经与岩心分析数据对比,新模型在储层渗透率计算中取得了较好的效果.

It is very important for oil and gas field exploration and development to accurately obtain reservoir permeability. SDR model and Coates model based on NMR are the most accurate classical models for reservoir permeability calculation at present. The classical SDR model and Coates model have achieved very good results in actual production, but have poor application effect in overpressure reservoir, and there is a large error between calculated permeability and core analysis permeability. Overpressure conglomerate reservoir has the abnormal characteristics of low porosity and high permeability, and the classical model of permeability calculation by NMR logging can not calculate the reservoir permeability. By analyzing the characteristics of overpressure reservoir and the influencing mechanism on physical properties, it is clear that overpressure intensity is the main controlling factor of permeability. A new method of constructing NMR permeability processing model of overpressure conglomerate reservoir by introducing overpressure physical property index and pore structure index based on SDR model is proposed. Taking the Permian Upper Wuerhe Formation in Mahu sag of Junggar Basin as an example, the petrophysical joint test of overpressured conglomerate reservoir is carried out to simulate overpressure. The effects of overpressure on porosity, permeability and resistivity of reservoir is studied, and the SDR overpressure permeability calculation model of overpressure conglomerate reservoir is established. Compared with core analysis data, the new model has achieved good results in reservoir permeability calculation.