Seismic Data Interpretation And Research On Structural Features In Qintong Depreesion Of Subei Basin

Qintong sag which is in the Northen Jiangsu Basin is one of the most oil-rich sags. Previous exploration and research only find out the local the fault-blocks, not structure interpretation and mapping systematically in the whole Basin Qintong. So we are in lack of the knowledge of the structural characteristics and hydrocarbon accumulation patterns in the area.In response to these problems, this paper made a more systematic study about district of the Qintong sag in Subei Basin and got following main results and understanding about by means of the application of structural geology, geophysics, petroleum geology, multidisciplinary theories, techniques and methods of fault system, structural styles, tectonic evolution, reservoir characteristics and favorable exploration;1, By researching the synthetic seismograms of several wells in the study area and calibrating accurately 10 the reflective layers, layer group characteristics of the various wave seismic reflection layer group characteristics were defined eventually and completed seven Structural maps of motivated layer through using well-seismic techniques, combination with tops of the wells and seismic layer;2, Qintong sag can be divided into general seven structural units, fault-terrace belt, deep sag belt,slope, oblique belt, external slope, the uplift belt on both sides of the sag.in the aspect of plane to have a checkerboard pattern structure with a zone in the North East into a zone and uplift(sag) in the North Eest (North South), to develop three major fault zones in Zhuzhuang-Zaoshe-Zongzhuang, Ziancheng-Zhuaiduo-Zingyu, and Zaoshan-Zhijiabao-Yinzhuang and to form four tectonic high belts in Gangkou-Nanhua, Zhuzhuang-Biancheng, Caoshe-Shijiabao, Hongzhuang-Taixing;3, The sag mainly developed stretch, stretch-slip two main types of structural styles, and can be broken down into seven sub-classes, constructors western style plane showed weak tensile strength slip, slip Eastern weak tensile strength of differences, the performance of the lower strata longitudinal stretch strong slip weak, strong stretch upper stratum weak strike-slip characteristics; structural traps are rollover anticlines, fault nose and fault block of three types; through Structural evolution history studies show that Qintong Cenozoic strata experienced depression-fault-depression three major evolutionary stages;4, Through the comprehensive analysis of hydrocarbon accumulation conditions, we has been clear about the main controlling factors of hydrocarbon accumulation in Qintong sag:① depth and volume of effective hydrocarbon source rocks control plane distribution of oil and gas;② good structural background is the main place to oil and gas reservoir rich integration; ③ the degree of reservoir development control the oil and gas accumulation and enrichment degree, finally through the comprehensive evaluation of oil and gas geological conditions, we found two favorable structural zones in the third member of Funing Formation,one favorable structural zone in Dainan Formation.