Seismic Identification And Description Technique For Deep Source Rock In Dongying Sag, Bohai Bay Basin

Dongying Sag is an important rich oil sag which takes on apparent feature ofcomplex reservoir in Baohai Bay Basin. With the increasing of exploration degree ofreservoir in mid-shallow formation, deep formation has become main exploration objectnow. However, there is not the bigger breakthrough in deep main exploration formationof interest in Kongdian formation. The reason for this is cognition deficiency for theirareal structure evolution, sediment feature and reservoir-forming rule, especially forhydrocarbon generating potentiality. Geophysical research for Ek2(second member ofKongdian formation) source rock has good realistic significance in the paper.Based on prior deep formation seismic research, seismogeology feature of Ek2isresearched with high quality bigger areal jointed3D seismic data and other geologic data,and sequence stratigraphy method. Seismic identification and description method isstudied by seismic data in area and strata with a little drilled wells and low degree ofexploration. A set of technique series is formed through researching of3years. A goodresult is acquired in real exploration and a new exploration prospect is presented for Ek inDongying Sag.Distribution feature of source rock in Ek2is researched firstly using prestack andpoststack seismic attributes in the paper. Four signs for seismic identification of sourcerock in Ek2are set up:①sequence features: typical reflection dense member, parallel orsub-parallel reflection configuration, no unconformity in the member.②dynamicsfeatures: high amplitude, low frequency, good continuity, time-frequency featurepresented inverse cycle.③kinematics features: low gradient member presented invelocity spectrum.④geometry features: with some thickness, distribution range andenough burial depth.The structural feature of Ek2in Dongying Sag is confirmed finely based on highquality bigger areal jointed3D seismic data. Thickness variation rule of interval ofinterest is determined. Distribution ranges of favorable source rock are delineated using seismic attribute and velocity feature. They are located in Xinzhen and Boxing areasmostly. Resource extent of source rock is predicted by seismic method firstly. Predictedresource extent is4.6×108tons. The role of seismic data and geophysical technique in oiland gas exploration will be important increasingly. This will provide reference for otherarea.