Study On The Tectonics And Reservoir Of Zilaitun Block In The South Of Huanghua Depression Area

Huanghua depression locates in the south of Yanshan Fold zone and west of Chengning Upheaval,tending towards to SW-NE,and belongs to a tectonic unit of Bohai Bay basin in the east of China. Bohai Bay basin is the biggest depressed area in the Huabei platform during Mesozoic and Cenozoic,but to the stage of Yinzhi,this area transforms to the Paleozoic Erathem floor tetonic framework of Huanghua Depression,and on the basis of floor tectonic,this area has been pulled and falled,coming into being tertiary fault basin.Zilaitun oil field lies in the south of Huanghua depression,locating to the north part of the west limb of Kongdian submoutain and north to west of Kongxi Fault. The faulting fold structure is the result of faulting block circumrotating,warping,lateral extrusion during Eiocene and Oligocene of Cenozoic on the basis of Mesozoic Folding movement.From the analysis of the faults distributing characters,the main part of faults have two group normal fault system with "lambdoidal shape"and trending towards to NE and NS separately.The backbone fault is the Litianmu Fault and Zao2301 Fault taking to NE,controlling the formation of sedimentary and structure of studing area.During the evolvement course of Zilaitun block of Huanghua Depression,the faulting action plays an important rule from early to late;the formation and movement of these faults controls the sedimentary entironment and distribution and evolvement of oil sag,on the same time,forming many advantaged structure traps,and having an important infuluence to the transfer of oil and gas.The sedimentary of studying area affected by the movement of Xishan,the south area of basin brought into pullment sinking,and formed a isolated sedimentary basin.Under this sedimentary surroundings,the Kongdian formation stratum has been formed.On the stage of Kongyi Member,the main sedimentary facies are the fluvial fan group and flooding plain,and going with the sedimentary surrounding of minitype limnological fluvial fan—gypsum saline.The advantaged oil conditions and rich resource are the physical basis of oil and gas reservoir.The thick oil stratum of hydrocarbon rock,the trap stratum of gypsum-mud rock,the reservoir stratum of sandstone with faceis of fluvial fan braided riverway and center beach. offers advantaged location for collection of oil and gas.The sedimentary facies zone of Zilaitun area determines the characteristic of reservoir as following sandstone reservoir,high interstice,high infiltration.The mian type of reservoir is lithological-tectonic reservoir,and then lithological reservoir.The distribution rule of oil and water is mainly controlled by fault block structure, and that the richness of separately fault block oil reservoir has great difference.The formation of oil reservoir zone on Zilaitun area is controlled by many factors such as structure location, lithological change of reservoir,fault channels,way of oil resource.