Study Of Seismic Prediction To Fractured Reservoir In Songliao Basin And Hailaer Basin

Aimed at the geological characteristics of the deep zone volcanic rock and clastic rock inNorthern Songliao basin, and the fractured reservoir with basement crust of weathering inHailaer basin, according to the seismic and geological investigation clue, the predictionmethod to fracture reservoir before and after stack is studied by combining seismic forward andinversion,predictions are made to volcanic and clastic fractured reservoir in Yingchengformation, Xujiaweizi area, and the fractured reservoir with basement crust of weathering inSudert area. Mainly the following achievements are obtained:1 According to equivalent medium theory, the theoretical model of seismic anisotropy offractured rocks is set up, and forward modeling to seismic respond of fracture is conducted byapplying 3-D seismic wave equation modeling, whose result shows that, abnormal seismicwave will occur in opening fracture developing band, which is mainly represented by changesin characteristics of amplitude, frequency, phase etc. of seismic waves. The exist of directionalhigh angle fracture will result in azimuthal anisotropy, thus the seismic attributes in eachdirection will present oval characteristics. Compression of the oval represents for fracturedensity, while long axis of the oval for fracture trend. The changes of amplitude withdirectional angle increases with the increase of offset distance.2 The seismic data of amplitude, wave shape and phase characteristics should berelatively maintained for fracture detection;pre-stack fracture detection should make fully useof data with large offset distance, in order to observe the changes of attributes with directionalangle. Therefore, the seismic data should satisfy the collection with wide direction and largeoffset distance, and the fold and offset distance in each direction should be evenly distributed.3 Through analysis to tectonic stress field, pre-stack and post stack seismic attributes, thecomprehensive prediction method to fractured reservoir is studied. Post stack seismic attributessuch as seismic energy fractile frenquecy, dipping angle variance, instantaneous dipping angleetc. can be used to predict fracture developing band. Based on the relationship between stressfield numerical simulation, tectonic curvature analysis, maximum strain, maximum stresswith stress directional angle etc., the developing degree of tectonic fracture can be judged.Elastic parameter such as impedance, velocity, Poisson ratio etc. and pre-stack amplitude,frequency attributes can be used to quantitatively predict the fracture density and direction.4 The research indicates that most of the fracture developed band of volcanic rock in Yingyimember, Xujiaweizi area, Northern Songliao basin are located near faults, high fracture densityis mainly developed at left side of NNW faults. Fracture directions are dominated by NNW, SN,with some near EW, corresponding with the direction of regional tectonic stress. Clastic fracturedeveloped band and its direction of Yangsi member is evidently related with fault system, mainlydistributed near the main faults. Fracture directions are dominated by NNW, SN, with some nearEW. high fracture density is mainly developed at left side of NNW faults.5 The research indicates that the development of basement crust from disintergration inSudert area of Hailaer basin is controlled by formation lithology and tectonics. The main fractureis appromately parallel to the trend distribution of near east-to-west faults. The fracturedeveloped area is located in Bei 15 well faults, eastern faults nearby, around northern Bei 19 welland the eastern faults nearby, extending to the direction of northeast.