准噶尔盆地乌夏地区压扭断裂带发育特征及其组合样式分析

Development characteristics and geometric pattern analysis of compression-torsion fault zone in the Wuxia area of Junggar Basin

压扭断层的几何学特征及其演变规律较为复杂,需要不断深化认识,这对西部压扭盆地具有很大的油气勘探实践意义。野外露头区勘查和高密度三维地震数据体处理成果揭示,准西北缘乌夏地区发育的高角度逆冲断层普遍具有走滑特点,并伴有多组系次级剪切断层,从而形成典型压扭断裂带。碎屑岩层系能干性差异控制压扭断层垂向脱耦传播和分段发育,构造活动强度变化进一步控制断层发育组系及其组合样式的变化。自深层至浅层随着压扭强度的逐渐减弱,压扭断裂带在剖面上存在“辫”、“花”和“阶”状3种基本组合样式,对应平面上呈“网结”、“羽列”和“雁列”状展布。已发现油气田剖析结果表明,不同组合样式断层的油气垂向输导能力存在很大差异,是控制压扭叠合盆地油气资源空间分布的关键因素。

The geometric characteristics of compression-torsion faults and their evolutionary laws are complex and need to be further understood,which is of great practical significance for oil and gas exploration in western compression-torsion ba⁃sins.It is revealed by the field outcrop exploration and high-density 3D seismic data process result that the high-angle thrust faults are characterized by notable strike slip accompanied by multiple series of secondary shear faults,forming a typ⁃ical compression-torsion fault zone in Wuxia area in the northwestern margin of Junggar Basin.The competence difference of clastic rocks controls the vertical decoupling propagation and segmented development of the compression-torsion fault.The intensity of tectonic activity controls the fault development series and geometric patterns.The profile geometric pat⁃terns of compression-torsion faults are identified in“braided”,“flower”,and“step”shapes,corresponding to the plane dis⁃tribution patterns of“network”,“plume”,and“echelon”from deep to shallow layers with the gradual decline in intensity.The discovered oil and gas reservoirs cast light on the significant differences in vertical oil and gas transmission capacity of compression-torsion faults with different geometric patterns,which is a controlling factor for the spatial distribution of oil and gas resources in the compression-shear basin.