塔北哈拉哈塘地区走滑断裂分段特征及其与油气成藏的关系

摘要

塔北哈拉哈塘地区奥陶系碳酸盐岩油气资源丰富,走滑断裂是该地区油气成藏最主要的控制因素.基于最新的高精度三维地震资料,借助最大波谷振幅属性提取的物探手段,结合走滑断裂的理论模型,探讨了哈拉哈塘地区走滑断裂的分段特征及其与油气成藏的关系.研究表明,哈拉哈塘地区主干走滑断裂平面不是连续不断的,而是由一系列雁列排布的R剪切断裂组成,具有明显的分段性:断阶带(overlap)发育成的P剪切断裂与R剪切整体构成辫状的构造样式;而在R剪切末端,派生出R′剪切、T剪切等次级断裂,组成马尾或羽状构造.不同区带具有不同的油气成藏条件:断阶带,受挤压应力控制发育局部背斜,为油气运移的长期指向区,而背斜翼部沿断层发育的串珠储集体为油气聚集提供了有效空间;走滑断裂末端的马尾构造区,断裂数量多、地势低,发育规模储集体,但油气易沿断裂向高处运移,油气保存条件较差.%The Ordovician carbonate reservoirs of Halahatang Area,North Tarim Basin,have rich oil and gas resources.It is recognized that the strike-slip faults are the main controlling factors of hydrocarbon accumulation in this region.Based on the 3D seismic interpretation and the maximum trough attribute extraction technique,the formation mechanism,structural characteristics and the relation between the fault and reservoirs are illustrated.Our studies show that,en echelon arranged R shears develop,and form an anastomosing zone with the linking of P shears.At the same time,R′and T shears develop at or near the tips of R shears,which constitute horsetails or wing cracks.Local uplifts form at the contraction overlaps,and the reserving spaces develop at the locations of faults along the fold limb.Branch faults have weak active intensity and shorter time,resulting in being more favorable for oil and gas preservation.In the horsetails structure zone,the number of faults is large and the topography is low,leading to widely developed reservoirs.However,the oil and gas may easily migrate from low to high along the faults,and the preservation condition is bad.