正演模式下成岩作用的温压效应机理探讨与启示

Effect of Temperature and Pressure on Diagenesis Using Forward Modeling

为了探讨核心地质要素对成岩作用的影响,本文选取硅质人造砂为研究对象,从正演物理模拟的角度定量研究成岩作用对温度、压力与时间的响应特征。实验结果表明:硅质人造砂岩压实作用强度与压力、温度具有正相关关系,石英等自生矿物结晶度对温度响应明显,非晶态硅质向晶态转化的模拟温度应低于400℃。在温度一定情况下,矿物结晶与压力呈抛物线型关系,存在优势压力区间,硅质结晶对应的压力在137.5 MPa左右,压力对成岩作用贡献包括压实作用与热能效应两个方面,以压实作用为主;在成岩作用过程中,反应时间可适当补偿温压不足造成的成岩效应差异,其对化学成岩作用贡献大于压实作用。相关成果可为成岩作用数值模拟与定量研究提供参考,进一步推动成岩作用机理的深化研究。

This paper investigates and discusses the effect of key geological factors on diagenesis.Siliceous artificial sands are chosen as object of study.Response characteristics of diagenesis to temperature,pressure,and time are quantitatively studied from the perspective of forward physical simulation.The results indicate that,the compaction of siliceous artificial sandstones increases with pressure and temperature.Temperature has the most significant effect on the crystallinity of authigenic minerals like quartz.In the simulation,the transformation of amorphous silica to crystalline occurs under the temperature of 400℃.In a certain range of temperatures,there is a parabolic correlation between mineral crystalline and pressure,with a dominant pressure range.Best pressure for siliceous crystalline is around 137.5MPa.The pressure contributes to diagenesis in two ways,i.e.,compaction and thermal effect of which the former is more significant.During the process of diagenesis,longer reaction time may compensate temperature and pressure.Reaction time has greater effects on chemical diagenesis than compaction.Results of this research are of great reference value for diagenesis numerical simulation,quantitative study,and further research in mechanisms of diagenesis.