同生断裂分段生长特征及其石油地质意义——以辽河西部凹陷鸳鸯沟断裂为例

为了研究同生断层的分段生长特征及其对油气运聚成藏的控制作用,以辽河西部凹陷鸳鸯沟断裂为例,采用最大断距相减法恢复鸳鸯沟断裂古断距,反演其活动历史,同时对比区域地质资料,提出了鸳鸯沟断裂在凹陷东部边缘郯庐断裂所诱导的右旋走滑构造系统影响下,具有右旋张扭的特征,沿其走向由西向东逐渐破裂、分段扩展:西段和中段最先发育于沙四段—沙三段沉积时期,断裂在沙二段—沙一段沉积时期为相对静止,东段在东营组沉积时期新生发育,断裂各段在馆陶组以来连结为一条统一的大断裂.研究结果表明,鸳鸯沟断裂分段生长的古调节带为油气聚集的有利区带:1)古调节带为物源进入凹陷区的优势入口,为油气聚集提供有利的储集砂体;2)古调节带构造变形复杂,发育断层、岩性及复合型油气圈闭;3)古调节带使得断裂下降盘发育横向背斜构造为油气运聚的有利指向区.

Characteristics and significance of syngenetic fault segmentation in hydrocarbon accumulation, an example of Yuanyanggou fault in western sag, Liaohe depression

To research on the characteristics of segmentation and its controlling effects on the accumulation of hydrocarbons in the syngenetic fault,an analysis was carried out on palaeo-displacement and activity history of Yuanyanggou fault using the largest displacement subtraction method,and then compared the regional geology informations.It is proposed that the Yuanyanggou fault which was affected by the dextral strike-slip structural system induced by Tanlu fault zone in the eastern edge of the Western sag,has the characteristics of dextral extensional-shear,gradual eruptions and segmental extension from west to east along its strike.The western and middle parts grew in Es3-Es4 period,and then stopped growing in Es1-Es2 period,whereas the eastern part was formed in Ed period.However,the three fault segments manifested in a united fault after the Ng period.The results show that the Paleo-accommodation is more favorable for the hydrocarbon accumulation because: 1) It provides reservoir space for hydrocarbon accumulation when material resources enter the sag;2) Its complex deformation forms fault,lithology and complex traps;3) It controls the formation of transverse anticline structure at the downthrow block,which is an advantage area for hydrocarbon accumulation.