塔里木盆地沙漠区超深层碳酸盐岩地震资料精细处理技术

Application of high-precision seismic processing technology for ultra-deep carbonate reservoir in the great desert area,Tarim basin,NW China

塔里木盆地超深层海相碳酸盐岩油气资源丰富,但勘探面临诸多挑战:其地表为塔克拉玛干大沙漠,出露巨厚沙丘,静校正和吸收衰减严重;上覆火成岩,多次波发育,信噪分离困难;埋藏超深,大于6000 m,深层分辨率低;受二叠系火成岩影响,速度变化大,深度域精准建模难度大。通过十余年不懈攻关,逐步形成了沙漠区超深层碳酸盐岩地震资料精细处理技术,其中,微测井约束层析反演沙漠区近地表结构,可以有效解决时间一致性问题;多信息综合识别长程及短程层间多次波,能够针对性压制提供优质的预处理道集;采用波动方程近地表Q补偿,可以解决沙漠吸收衰减问题,提高深层分辨率且目的层主频能够提高5 Hz;VSP井控和火成岩小网格层析提高深度域建模精度,可以确保碳酸盐岩高精度成像。大沙漠区超深层碳酸盐岩地震资料高精度成像技术,可精准刻画出走滑断层和缝洞,有效支撑了塔里木盆地1×10^(9)t级富满油田的勘探发现。

The ultra-deep marine carbonate formation of The Great Desert,Tarim Basin Area,NW China,hosting great potential reservoirs,is a prospective target for petroleum exploration.However,there are several challenges remain in ultra-deep desert seismic data processing:①Loose structures of near-surface in desert regions can bring severe seismic energy absorption,showing distinct low-frequency characteristics,which will eventually affect the reconstruction of signals;②The differences between interlayer multiple wave and primary wave in travel time and velocity are relatively small in desert area.Therefore,it is much more challenging to identify and suppress interlayer multiple waves;③The relatively low-resolution seismic data in ultra-deep area(depth>7500 m)due to energy absorption and wavelet deformation cannot meet the requirement of high-precision imaging;④The drastically varying velocity medium under the influence of lithology,primarily consisted of Permian igneous rocks and Calcareous limestone,causes excellent difficulties in velocity model building.We attempt to achieve high-precision exploration progress in Tarim basin:①We use microlog data to constrain the near-surface model building;②The multiple suppression technology we are applying this paper can provide more accurate pre-stack data;③We adopt near-surface Q filtering and migration for high-frequency compensation to improve the seismic resolution;④We build the initial velocity model based on VSP data,update the initial velocity model with tomography,finally obtain high-precision imaging of ultra-deep carbonate.