The significance of a piecemeal geometric model of mudstone compaction: Pinghu Slope, Xihu Depression, Eastern China

The geometric model of the loading curve used to express mudstone compaction behaviour profoundly influences the quantitative estimation of pore-pressure and identification of the origin of overpressure. The verification of field data from the Pinghu Slope Belt indicates that as burial depth increased, the compaction process was divided into three sections of mechanical compaction fitted by a convexity function, chemically enhanced mechanical compaction fitted by a concavity function, and stable compaction fitted by a convexity function. The piecemeal geometric model of mudstone compaction expressed by the loading curve is more appropriate than previous monotonous loading curves for characterising compaction behaviour, amplifying the effect of chemical compaction, and expressing chemical compaction behaviour. The piecemeal geometric model of mudstone compaction behaviour yields more precise results of formation pressure prediction and overpressure origin identification.

Automated summary

The study shows that as burial depth increases, mudstone compaction can be divided into three sections: mechanical compaction, chemically enhanced mechanical compaction, and stable compaction. Using a piecemeal geometric model of loading curves can provide more accurate predictions of formation pressure and identification of overpressure origins.