This paper develops a structure-preserving variational integrator for geometrically exact beam in Hamel’s field formalism. A simulation illustrates that the derived algorithm preserves energy, momentum and geometry structure.

On the base of the evidences on structure geology, the paper presents that the natural gas in Kuqa basin of Northwestern China comes mainly from the north thrust belt. Firstly, based on the basin prototype, the Triassic and Jurassic mudstone and coal, the main source rocks of the basin, did not develop better in Baicheng sag than in the northern thrust belt including Keyi structural belt; Secondly, because of the thrusting happened in late Cenozoic, the Triassic and Jurassic source rocks reach to a high to over high maturity and thus generate gas or condensate oil mainly. Thirdly, the thrust faults compelled the natural gas to migrate from the north to the south or from the deep to the shallow. As a result, the Keyi structural belt and the eastern Qiulitage structural belt enriched in natural gas because they were not only located on the migration routines of the natural gas, but also developed simultaneously when the gas migration happened.