Abstract:

The structural characteristics such as vertically stratigraphical sequence hiatus,planar sedimentary system and facies incompleteness,delimitation of a basin by erosion or fault,and the structural feature of outcrop in peripheral and near arears could be taken as marks in recognizing relict basins.Most the relict basins underwent multi-tectonic superposition.According to the theory of system and information,the multi-tectonic superposition could be abstracted as the processes of construction,structure and the information record.Then use antitone structural analysis method to recognize and reconstruct the primary tectonic structure and sedimentary feature of a basin in certain geological history.The method includes mainly several key technologies such as tectonic imaging,the determination of deformation age and deformation reversion.Usually one should adopt two steps to assess the petroleum geological conditions in relict basins:(1)use inversion technology to reconstruct the structural framework of the prototype basin,the deposition feature and the primary oil and gas geological feature of the prototype basin;(2)use forward solution to theoretically analyze the prototype basin,then compare the analysis results with actural basin,and correct the effect of subjective factors.On this basis,the space structural hierarchy,the time order and time-space coupling relationship of hydrocarbon generation,pool-forming events could be found,and then oil and gas generation and accumulation regularity could be further understood.

Key words: relict basin, structural analysis, oil-gas geology, assessment