鄂尔多斯盆地南部泾河油田延长组板内走滑断裂内部结构刻画

Characterization of Architecture of Intraplate Strike-Slip Faults in Yanchang Formation of Jinghe Oilfield in Southern Ordos Basin

板内走滑断裂的内部结构具有控储和控藏作用.在断缝体油气藏勘探开发过程中,由于走滑断裂带内部结构具有高度非均质性,需要对其内部结构进行刻画.综合岩心、测井和地震资料,对鄂尔多斯盆地南部泾河油田延长组走滑断裂带进行了走向分段和侧向分带研究,并提出了利用综合裂缝指数测井(comprehensive fracture index log,CFI)和断层形态指数地震属性(fault shape index attribute,FSI)累积曲线定量划分损伤带边界的方法.结果表明,泾河油田延长组走滑断裂带以张扭段和走滑段为主,压扭段仅少量发育.CFI和FSI均与裂缝密度呈正相关关系,根据累积CFI和累积FSI曲线的梯度变化可以刻画地下走滑断裂的损伤带边界.泾河油田延长组走滑断裂带内单条断裂的宽度主要在160~300 m,且张扭段的宽度最大,其次为压扭段和走滑段.

The architecture of intraplate strike-slip faults plays an important role in controlling reservoir properties as well as hydrocarbon migration and accumulation.In the process of exploration and development of strike-slip fault-controlled fracturing reservoirs,the architecture of the strike-slip fault zone needs to be characterized because of its high heterogeneity.Taking strikeslip fault zones of the Yanchang Formation of the Jinghe oilfield in the southern Ordos basin as an example,in this paper it conducted fault segmentation along the fault strike and lateral zonation along the fault dip by integrating core,logging and seismic data.In this paper it puts forward a method to quantitatively detect damage zone boundaries by cumulative curves of comprehensive fracture index log(CFI)and fault shape index attribute(FSI).The results show that strike-slip fault zones of the Yanchang Formation in the Jinghe oilfield are mainly composed of transtensional and strike-slip segments,and transpressional segments are rarely developed.CFI and FSI are positively correlated with fracture density,and damage zone boundaries can be detected according to the gradient change of the cumulative curves of CFI and FSI.The width of a single fault within the strike-slip fault zones in the Yanchang Formation of the Jinghe oilfield is mainly between 160-300 m,and the average width of transtensional segments is the largest,followed by transpressional and strike-slip segments.