Study For Continental Fades Stratum Subtle Traps: A Case Study From Tertiary System Qikou Depression, Huanhua Sag

Forecasting subtle trap by sequence stratigraphy and 3D seismic data is a sensitive topic in hydrocarbon exploration. Search for subtle trap by geophysical data is the most popular and difficulty. In this paper, using sufficiently drilling data , log data-, core data and 3D seismic data ,stratum sequence Qikou Depression, Huanhua Sag is partitioned by using sequence stratigraphy theory. Each sediment sequence system mode is built. Sediment faces of subtle trap are pointed out. Dominating factors of forming subtle trap are analyzed. Sandstone seismic rock physics and its response are studied in Tertiary System. Sandstone geophysical response and elastic modul vary laws with pressure , temperature , saturation, liquid character in high pressure & high temperature are studied. Experimental relationships between geophysical characteristic parameter and pressure , temperature, porosity, depth are built. They are basic data for subtle trap study. Experimental result and practice shows it is possible using seismic information forecasting subtle trap. Integrated using geology % log, drilling data ,specia! seismic processing technique-, interpretation technique, including high precision horizon calibration technique, 3D seismic visualizing interpretation , seismic coherence analyze, attribute analyze, logging-constrained inversion, time frequency analyze , ANN forecasting technique , subtle trap object is identified and interpreted .Finally, advantage object of subtle trap in this area is determined. The importance results and achievements in this thesis are follow:(1) Stratum sequence Qikou Depression, Huanhua Basin is partitioned using sequence stratigraphy theory. 6 third class sequences are identified. Each sediment sequence system region and system distributing law is studied. Many times structure movements of Huanhua Basin result in many times water progradation and retrogradation. Cycle sediment in portrait and stratum lapout & denudation in plane and vary of different types sand body are resulted in sediment process. It provides better condition for subtle trap. Middle part of basin is centralized distributing area of subtle trap. Immanent factors forming subtle trap is many times spread of lake water body. Many large land-carriage clastic system provide large deposit space. Ancient heave slope band controls distributing of subtle trap.(2) Sedimentation cycle study method and technology using wavelet time frequency analysis theory is mostly studied and exploited. Theory model and practical test all indicate that sedimentation cycle study in wavelet time frequency domain is feasible .A power tool is provided to sequence stratigraphy application for oil & gas exploration and exploitation.(3) P and S wave velocity and dynamic & static modul of sand rock in Huanhua Basin are the first time measured using "MTS Rock physical parameter testing systemunder formation condition" of "state key laboratory of oil and gas reservoir geology and exploitation". At the same time, relationship between seismic response and oil & gas is discussed and summarized. Research shows: change of temperature & pressure of sand rock results in prominent change of seismic P and S wave velocity and dynamic & static modul and seismic attenuation of sand rock. Change of pore liquid character and saturation results in change of seismic P and S wave velocity and attenuation of sand rock. Experimental relationships between geophysical character parameter and pressure - temperature -. porosity -. depth are built.(4)Research shows that "bright spot" is seismic response character of shallow oil & gas sandstone Huanhua Basin.(5)When hydrocarbon compound is coved by thick shale , hundreds meters low velocity gas incursion diffuse band is seen clearly above sandstone in Huanhua sag . Sometimes bulk and range of incursion diffuse band is large than hydrocarbon compound accumulate body. Its seismic response must be recorded. It is likely to recognized oil & gas sandstone using seismic method.(6)Finally, colligati...