济阳坳陷孤北潜山地质构造与油气富集规律

GEOLOGICAL STRUCTURES AND HYDROCARBON ENRICHMENT REGULARITY OF GUBEI BURIED HILL IN JIYANG DEPRESSION

济阳坳陷东北部的孤北潜山,面积60km^2,有厚约1200m 的古生代碳酸盐岩沉积,已发现5条逆断层和两个倒转背斜,这些构造的形成与郯庐大断裂的左行剪压活动有关。背斜与潜山成正地形关系,其顶部张裂隙发育,经中奥陶至中石炭世风化剥蚀,孔、洞、缝发育;潜山被生油凹陷包围,油源丰富,油气通过断面和风化壳进入潜山,形成新生古储的次生油气藏。主力产层是奥陶系顶部风化壳,油气最富集部位是孤北潜山倒转背斜中部高带。

Gubei buried hill,with an area of 60km^2 and 1200m thick Paleozoic car-bonite sediments,is situated in the northeast seashore of the Jiyang Depres-sion.5 reverse faults and 2 overturned anticlines have been found here.The formation of the reverse faults and the overtured anticlines wererelated to the sinistral shear-compression of the Tanlu huge fracture andthe obstruction of Chengning uplift.A lot of fissures developed on the top ofthe anticlines due to tensil stress.After long time weathering and erosionfrom the Middle Ordovician to Middle Carboniferous,pores,caves and crevicesdeveloped in the weatherd crust of Ordovician,thus providing favourablespace for hydrocarbon enrichment.Surrounding by source sags,the buried hill has developed into secondaryoil pools with young source beds and old reservoiring beds.Majorproductive bed is the weathering crust of the upper part of the OrdovicianSystem,but the most rich positions are higher levels in the central part ofthe overturned anticlines.