页岩气藏高效开发依赖于高精度三维地震资料,而覆盖密度是决定三维地震资料品质和投资成本的关键参数.针对四川盆地泸州区块海相页岩气三维地震资料,在确保对比因素单一性的前提下,通过抽炮排列将覆盖密度由原始的52.5×104道/km2逐步退化为6种不同覆盖密度的三维观测系统,并对其叠前偏移成果进行定性、定量评价以论证和优选覆盖密度参数;同时对比了相同覆盖密度下大面元高覆盖和小面元低覆盖两种观测系统的优劣.结果表明:①叠前偏移成像效果随着覆盖密度的增大而逐渐改善,信噪比也随之提高,振幅、频率、信噪比的定量评价显示泸州区块页岩气三维地震观测系统覆盖密度选择在42.0×104道/km2较为合适;②在相同的覆盖密度下,大面元高覆盖观测系统能够提高地震资料的信噪比,有利于复杂构造的成像,而小面元低覆盖观测系统则有更高的纵横向分辨率.结论认为:开展覆盖密度参数退化试验,综合定性和定量评价结果能够获得一个兼顾成像效果和经济性的覆盖密度参数;在覆盖密度确定的前提下,对于信噪比较高地区,可以选择小面元低覆盖观测系统,而对于信噪比较低地区,可以选择大面元高覆盖观测系统.

随着GNSS测量技术的发展与应用,其平面坐标和大地高可达到mm级定位精度,GNSS大地高转换为正常高的质量和精度,已更多的取决于获取高程异常值的精度.本文提出了一种综合利用EGM2008地球重力场模型和研究区域适量GNSS/水准控制点,利用"分级移除-克里金空间插值拟合-恢复"法快速准确获取高程异常值并建立了四川盆地Cm级精度的高程异常值库.实践表明:采用上述方法,拟合精度可达到四等水准测量的精度要求,远优于现行石油物探测量行业标准相关要求,为石油物探GNSS测量高程转换提供了低成本、高效率的技术选择方案.

In order to realize the optimistic design of 3D seismic prospecting and observation system adaptable to mountain characteristics,this paper develops a design software for the GeoMountain 3D Observation System,which solves problems such as complicated logical processing of layout and design in observation system,coordinative relations between functions and calculation accuracy in a better way.This software adopts advanced vector map processing and large capacity data processing with high efficiency,the application of which shows that this software system can finish designing the observation system of a 3D working area(even a super large one) in an efficient and correct way.

In order to get accurate calculation result of seismic interval velocity by use of velocity spectrum,this paper,taking the GeoMountain Seismic Interpreter System as a platform,puts forward a new calculation method of interval velocity including general DIX interval velocity calculation method restricted by regional empirical value,backstepping calculation method through the known interval velocity spectrum based on general DIX formula,horizon-based calculation method of interval velocity and azimuth smoothening etc.Examined by the actual structural map of Mopan-Laowan working area in East Sichuan basin,the interval velocity calculated by this method showed a better rule in lateral variation and coincided better with the actual geological conditions.