| On the basis of predecessors' research results,comprehensive application of seismic data,well logging and mud logging,core and etc,guided by structural geology and geotectonics,sedimentology,petroleum geology,oil and gas field development geology and etc,based on the qualitative analysis,deepened on the quantitative analysis,applying the methods of seism and logging to geology,closely connecting the analysis of structure and sedimentary and petroleum entrapment,that they were the fault system,structural evolution,sedimentary evolution and accumulation elements,and the relationship of structure,sedimentary was systematically researched,and petroleum entrapment was deeply researched,and the favorable oil-bearing area was forecasted.According to the structural interpretation of seismic data,the faults in Wubao fault zone were divided into first order faults,third order faults and fourth order faults.The study on fault combination styles showed that the surface combination styles of the faults in Wubao fault zone were mainly in echelon,feather,branch and net,and the section combination styles were mainly in reverse trapezium,negative flower,“y” shape and reverse “y” shape.Recovery of eroded thickness late in Sanduo Formation showed that,the eroded thickness on footwall was between 1400m-1700 m,and that on hanging wall was between800m-1100 m,and it was bigger on footwall than that on hanging wall,and bigger near Wu?1?fault and reduced towards to sag,with the trend of bigger in northeast and smaller in southwest.Recovery of eroded thickness late in Funing Formation showed that the eroded thickness on footwall was between 200m-700 m,and it was bigger near Wu?1?fault and smaller far from Wu?1?fault,with the trend of bigger in northeast and smaller in southwest.The result of recovery of eroded thickness in two stages showed that the tectonism was stronger late in Sanduo Formation than that late in Funing Formation,and it happened regional eroding late in Sanduo Formation and local eroding late in Funing Formation.The study on recovery of eroded thickness,structural evolution sections and fault activity intensity in Wubao fault zone showed that the structural evolution in the area can be divided into five stages: the first stage was from Pukou period to Chishan period when the faults developed in footwall;the second stage was from Taizhou period to Funing period when the formation was tilted rotated and the slope was formed;the third stage was from Dainan period to Sanduo period that the differential settlement happened in Wubao fault zone;the fourth stage was in the end of Sanduo period when the thrust folds happened in the study area;the fifth stage was from Yancheng to Dongtai period when was in the stable structural stage.Based on the statistical research of the fault strike in Wubao fault zone,the analysis of tectonic stress showed that the tensile stress direction was SE140 °-NW320 °from Taizhou period to Funing period in Wubao fault zone and was SE160 °-NW340 ° from Dainan period to Sanduo period.The simulation results of tectonic stress field in Sanduo perid showed that,under the influence of north-south tensile stress,the stress trajectory appearing in the fault zone indicated that the fault remained active,and the north-south tensile stress trajectory ? 3 appearing in the area away the fault zone indicated that the east-west faults developed,and along with moving closely to the fault,the north-south ?3 gradually turned to northwest,and ? 3 close to the fault roughly perpendicular to the fault strike showed that the normal faults parrallel to the boundary fault could develop.Based on stratigraphic division and correlation,according to the core observation and analysis of well logging,mud logging and seismic data and etc,the point-line-surface study of single well facies-even well facies-planar facies suggested that,in Wubao low bulge,the source of Taizhou formation to 1st member of Funing formation was mainly from Tongyang uplift,and 1st member of Taizhou formation was mainly braided river delta plain subfacies and front subfacies,and 1st member of Funing formation was mainly delta front subfacies;in the steep slope zone,the source of Dainan formation was mainly from Wubao low bulge,and1 st member of Dainan formation was mainly slip turbidite fan and semi-deep and deep lake,and 2nd member of Dainan formation was mainly fan delta;1st member of Sanduo formation w a s m a i n l y b r a i d e d ri v e r a n d t h e in t e r f l u v i a l lo w l a n d s w a s mo s t l y d e v e l o p e d.Combined with the regional tectonic back ground,based on the study of the structural characteristics,structural evolution,the active intensity of faults,the sedimentary facies andsedimentary evolution,the control function of structure on sedimentary was further studied and the result showed that,in Wubao low bulge,the slope palaeotopography of trapezium during 1st member of Taizhou to 1st member of Funing control the formation presenting wedgelike and thick in southeast and thin in northwest;the steep slope topography in the hanging wall of Wu?1?fault and the a active intensity of Wu?1?fault controlled Dainan formation presenting bead like,and further study indicated that,in the area where the throw is big,the source in the footwall was into the lake then deposited in the hanging wall,and the palaeotopography in the north of study area was high and became low in the south,so the source was mainly from the northwest,and the source in the footwall was deposited in the southeast of hanging wall.The throw of palaeotopography was slow in Sanduo period and the activity of Wu?1?fault was weak,so the formation was distributed in the whole study area.Based on the study of structural characteristics and sedimentary characteristics,the accumulation elements,the effects of structure and sedimentary on oil-gas accumulation were deep analyzed,and the law of oil & gas accumulation and oil & gas reservoir-formed mode were summarized,and it suggested that the reservoirs in the area was mainly presenting zonal distribution along Wu?1?fault or parallel to Wu?1?fault and there were two reservoir-formed modes: one was double sources providing hydrocarbon and migrated vertically and the other was single source providing hydrocarbon and migrated vertically.the favorable area was E2d12-9 between well zhou27 and well zhou 36 in the steep slope. |
PDF Full Text Request