Abstract: Seismic data obtained in the folded zone in Eastern Sichuan Basin show that sediments cover in this area consist of several separated structral sequences. Some plastic formations with certain thickness act as separators. Among them, the Permo-Carboniferous carbonate sequence is one of most interest objects in hydrocarbon exploration. In cosespondence to a simple Jurassic surface fold anticline, the Permo-Carboniferous structure is generally decomposed to several falted blocks with different features. It may be summarized to a structural mede with five-blocks generally, namely, back steep block; up thrust block; front steep block; sag block and counter thrust block in sequence. The complex data of a large number of wells indicate that hydrocarbon pools may be found both on up thrust and counter thrust blocks. Herein, the gas pools in Carboniferous dolomite are structural and fault traps, whereas the gas pools in Permian limestones are naturally fractured traps, with fractures developod in each arch on these two blocks. Tracing a series of cross sections in a structure, the evolution of such a structure as the result of horizontal stress may be studied. In this paper, an actual example is presented. Such a study is halpful to explain the mechanism of the formation of various structural characteristics in the discussed area. Another distinction of the P-C structure from its corresponding surface one is the intersection of the strike of various blocks in the same structure. It shows that the fold had subjected to multiple actions of tectonic stresses in various directions and various orogenic stages. It seems here that some superposition of folds should be considered. Field practice shows that such intersection is usually associated with developed fracture system and will result in high capacity wells as well as large hydrocabon reverse.

摘要： 四川盆地东部褶皱带沉积岩覆盖由几套塑性岩层相隔,可分为若干相互有差异的构造层系。其中石炭二叠系的碳酸盐岩层系,是重要的找烃目的层系之一。对应地表一个单一的侏罗系褶皱背斜,石炭二叠系构造往往解体为若干不同特征的断块,并且可以归纳为一个五块体的构造模式。它们依次是后沿陡折块、上冲块、前沿陡折块、坳陷块和反冲块。钻井的综合资料表明,烃储存在于上冲块和反冲块上,其中石炭系气藏为构造和断层圈闭类型,二叠系气藏则为裂缝圈闭类型。裂缝发育于对冲两块的拱曲之中。追踪和分析一个构造不同部位的一系列剖面,可以得出由水平应力作用而形成的构造的发展演化过程。本文列举实例分析了各种构造特征的形成机理。石炭二叠系构造与地表构造的另一个区别是,同一构造不同块体的走向可以是交叉的,说明褶皱的形成经受了不同时期不同方向的多次应力作用,即存在着褶曲的叠合。实践表明,两组褶皱轴线交汇的部位,往往裂缝特别发育,可以找到较高的产量和储量。