Analogue experiments on the piggyback propagation in northwestern Sichuan and latest propagation in its deeps

Abstract

Recent explorations reveal a great potential for oil and gas resources in the northwestern Sichuan foreland basin. However, constrained by multi-phase tectonic activities of the Longmenshan-West Sichuan foreland system and the deep burial of the piedmont belt, there remain many uncertainties in the interpretation of petroleum structure models in the foreland concealed tectonic belt. Based on the geometry-kinematics-dynamic similarity theory between the foreland prototype of the northwestern Sichuan and the sandbox analogue model, two groups of controlled experiments were carried out (including standard scaled experiments and analogue experiments with a ramp-flat structure). The fold-thrust belt and foreland basin of the western Sichuan are controlled by two sets of main detachments of the Middle-Lower Triassic gypsum salt and the Lower Cambrian mudstone, leading the layered-style propagation to the foreland in the Late-Middle Cenozoic. The ramp-flat structure plays a profound influence on deep thrust and pop-up structures in the northwestern Sichuan foreland basin. Analogue results combined with seismic interpretation of the northwestern Sichuan illustrates that the main exploration potential may rely on the Paleozoic blind thrust and pop-up structures caused by the latest propagation to the northwestern Sichuan foreland basin.

Keywords

• physical analogue
• detachment
• ramp-flat structure
• propagation to the foreland
• thrust and pop-up structures
• northwestern sichuan