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On the basis of the pressure data ob- tained from the southern margin of the Junggar Basin, Northwestern China, the distribution and evolution of overpressures in high permeable sandy and in low-permeability shale formations are characterized. The evolution of overpressures in various structural processes, especially in erosion and mechanical de- formation, is quantified by numerical modeling stud- ies. The modeling results show that anomalies of high pressure observed in boreholes are likely a combination of several effects, i.e. 1) the compaction caused by overloading, 2) the compaction caused by lateral tectonic stressing, 3) lateral transmission of hydraulic pressure associated with fold formation, and 4) vertical hydraulic connection caused by opening faults crossing formations with different initial excessive pressures. The main mechanisms of overpressures and their distributions are defined.
On the basis of the pressure data ob- tained from the southern margin of the Junggar Basin, Northwestern China, the distribution and evolution of overpressures in high permeable sandy and in low-permeability shale formations are characterized. The evolution of overpressures in various structural processes especially in erosion and mechanical de- formation, is quantified by numerical modeling stud- ies. The modeling results show anomalies of high pressure observed in boreholes are likely a combination of several effects, ie 1) the compaction caused by overloading, 2) the compaction caused by lateral tectonic stressing, 3) lateral transmission of hydraulic pressure associated with fold formation, and 4) vertical hydraulic connection caused by opening faults crossing formations with different initial excessive pressures. The main mechanisms of overpressures and their distributions are defined.