盐下构造速度建模与逆时偏移成像研究及应用  

Application of velocity modeling and reverse time migration to subsalt structure

作　　者：刘文卿[1,2] 王西文[2] 刘洪[3] 王宇超[2] 王孝[2] 曾华会[2] 邵喜春[2] 

机构地区：[1]成都理工大学,成都610059 [2]中国石油勘探开发研究院西北分院,兰州730020 [3]中国科学院地质与地球物理研究所,北京100029

出　　处：《地球物理学报》2013年第2期616-625,共10页Chinese Journal of Geophysics

基　　金：国家自然科学基金重点项目"深层油气藏地震波响应的积分表达与计算研究"(40830424);国家油气专项"天然气复杂储层预测与烃类检测地球物理技术研究及应用"(2011ZX05007-006)联合资助

摘　　要：盐丘速度建模及成像是盐下油气藏勘探有关技术瓶颈问题.盐下构造由于盐丘速度与围岩地层差异大,且厚度横向变化大,造成地震波场复杂及时间域构造畸变.针对H区复杂盐丘的地质特征,通过技术创新重新认识盐下油气藏.针对盐丘速度建模的难点,提出了"多信息约束层控实体建模技术",采用序贯高斯模拟及克里金趋势约束速度反演方法,较好解决了盐下速度异常问题,大大提高了速度建模的精度;针对盐下复杂构造成像,基于有限差分方法研究了精确且高效的差分格式逆时波场外推算法.基于GPU/CPU协同平台,将波场延拓通过GPU实现.采用逆时偏移深度域成像技术,使高角度反射界面、甚至超过90°盐丘侧翼界面的反射波精确成像.通过盐丘理论模型试算验证算法及方法的正确性.上述方法解决了盐丘速度建模精度问题、盐丘侧翼的回转构造成像问题,实现了对盐丘边界及盐丘侧翼的准确归位.消除了速度异常造成的时间域构造畸变,使盐下地层在深度域能够准确成像.Velocity modeling and imaging of salt domes are bottlenecks m subsait reservoir exploration. Because of large velocity variance between salt domes and surrounding rocks and large thickness changing in spatial direction, many problems are present in subsalt seismic exploration, such as seismic wave filed complexity, and structural distortion in time domain. According to the complex geological characters of Area H, we can learn more about the subsalt reservoirs through technological innovation. As to the difficulties of salt velocity modeling, this paper proposes an idea called ＂ multi-information constrained layer-bound solid modeling technique＂, which uses sequential Gauss simulation and CVI method to solve velocity anomaliesin subsalt structure, and can remarkably improve the precision of velocity modeling. As to the complex subsalt structure imaging, through studying based on the finite difference method, this paper proposes a precise and efficient finite difference scheme for reverse-time wave field extrapolation. Based on GPU/CPU cooperating system, we extrapolate the wave field forwardly and reversely in time domain that needs the maximum amount of calculation through GPU. This paper adopts reverse time migration in depth domain, which can precisely image the reflected waves from steep dip （even exceeding 90 degrees in the adjacent beds of a salt dome）. By the theoretical test of salt dome model, we verify the correctness of the algorithms and methods mentioned above. Through the reverse time migration method, we solve the problem of imaging sub-salt structure and the adjacent beds, so we can migrate the salt dome and the adjacent beds to their true positions, and eliminate structure distortion of underlying beds in time domain due to the velocity anomaly of the salt dome. So fnianlly we can get precise migration results of sub-salt structure in depth domain.

关 键 词：盐丘 层控建模 多信息约束 逆时偏移 波动方程 GPU CPU协同计算 

分 类 号：P631[天文地球—地质矿产勘探]