Search

Paleo-pressure reconstruction in sedimentary basins is one of the most important aspects of hydrocarbon accumulation research. In view of the advantages and disadvantages of the current methods for paleo-pressure research, a new method to reconstruct the paleo-pressure is presented in this paper. According to the geological background, quantitative analyses of the factors that might control overpressure were first conducted to clarify the contributions of each mechanism during different geological periods. Pressure evolution was reconstructed by fluid-compaction modelling with constraints imposed by the paleo-pressures obtained from fluid inclusions or differential stress methods. Determining the mechanisms responsible for overpressures during geological history is the basic prerequisite for paleo-pressure research. Thus, quantitative studies were conducted of the contributions of disequilibrium compaction, gas charging, oil cracking, temperature reduction, and tectonic uplift and subsidence to overpressures. Three case studies of paleo-pressure reconstruction were performed for the Sinian strata in the Sichuan Basin, Ordovician strata in the north uplift in the Tarim Basin and the Permian strata in the Sulige Gas Field in the Ordos Basin, where these three study sites are normally pressured, weakly over-pressured and abnormally low pressured at present, respectively. The new method developed in this paper is very important for the practical reconstruction of the paleo-pressure in marine strata and ancient strata in deep basins. [ABSTRACT FROM AUTHOR]

The temperature history of samples and maximum palaeogeothermal profiles of boreholes were reconstructed based on low‐temperature thermochronology and vitrinite reflectance data, and the results provide limits for the timescale and amount of uplift–denudation of the eastern Sichuan Basin. The thermal history showed that the uplifting and cooling of eastern Sichuan Basin began around the Late Cretaceous (approximately 100–80 Ma). The region had experienced a continuous cooling process from the Late Cretaceous until the present, with the geothermal gradient decreasing from 32–36 °C/km to 20–23 °C/km. The amount of denudation at the Puguang region in north‐eastern Sichuan was approximately 2.3 km, whereas that at south‐eastern Sichuan was 1.9 km, and the erosion thickness in the eastern Sichuan fold belt that was revealed via the field samples is 2.3 ± 0.3–2.6 ± 0.3 km. The north‐eastern Sichuan experienced sustained cooling with inconspicuous fluctuations, whereas the thrust belt and the south‐eastern Sichuan Basin presented 2–4 stages with different cooling rates. It may indicate that the eastern Sichuan fold belt experienced a complex structural evolution, characterized by episodic upliftings and deformations since Late Cretaceous, while a different and gentle deformation took place in the northeastern Sichuan Basin. [ABSTRACT FROM AUTHOR]