Imaging of complicated geological structure is one of the major difficulties in the field of seismic exploration,and the main factor of imaging is migration of the velocity field.Therefore,constructing accurately the migration velocity field is not only the core of high precision imaging,but also the nexus between seismology and geology.In fact,the accuracy of velocity that is picked with the conventional method is rather low under the large offsets,dipping or bend interfaces,pre-salt and deep multilayered medium.As a result,it reduces the accuracy of seismic imaging as well as the reliability of imaging and interpretation.To solve this problem,a new method of PSTM velocity field building is adopted,that is,initial velocity of migration acquiring,bi-spectral high density velocity analysis and anisotropy PSTM.The practical result has proved its good effect and the real accuracy of migration has been increased much.

The Dongpu depression is a faulted basin with versatile depositional environment,broken fault-blocks and complicated structures.Its local structure is controlled by faults.There are major lateral velocity alternations because of different buried depths of contemporaneous strata in the two sides of faults.But time migration is unable to work out this problem,so anisotropic pre-stack depth migration has been applied to this area,and high density velocity analysis is ombined with acoustic logging data.The results show coincidence of seismic and drilling with anisotropy PSDM.

The main objective of conventional 3D seismic geometry design is to obtain regularly sampled stacking dataset, which can be used to achieve good images through post-stack migration.However, pre-stack migration has strict requirements on seismic geometries.In order to exert the technical advantages of pre-stack migration and improve the accuracy of seismic images, it is very important to design seismic geometries based on pre-stack imaging. This article puts forward an approach of seismic geometry design based on pre-stack imaging.The first step is to design the basic spatial sampling of seismic geometry based on the anti-aliasing criteria of pre-stack migration.The second is to design the layout of seismic geometry according to the rule of regular sampling and uniform bin attributes. Then, it optimizes step by step and finalizes seismic geometry by using techniques such as focal beams, pre-stack migration response of scatter point, forward modeling, and wavefield illumination.This method has been applied to high accuracy seismic exploration of the Zhongyuan Oilfield in recent years and it has obtained very good results.

According to seismic attributes of time windows and instantaneous moments,an improved algorithm based on the window of the instantaneous intensity ratio is proposed.The basic theory is that instantaneous attributes are computed with complex trace analysis and first arrival with the intensity ratio method.The results show that the effect of rolling time windows is poor and larger errors exist in the process of picking some special points.When using the instantaneous intensity ratio method,the event of first arrival curve becomes more smooth,and abnormal points have greatly reduced,thus the accuracy of picking is greatly enhanced.

The issue of static correction on the complex ground surface comes down to the solution of near-surface layer velocity,so the more complex the ground surface,the more difficult the velocity of near-surface layer to be obtained. According to the peculiarities of ground surface in the desert area such as the abnormally complicated surface condition,low signal-to-noise ratio of source data,and other involved problems,based on the analysis of surface structure,we conducted a study on several static correction methods including the first arrival refraction wave statics,the dune curve statics,and the tomographic inversion statics. According to the relationship between the spread velocity of seismic wave inside the dune and the thickness of the dune,the dune curve statics was improved in this way that in actual calculation,either the quadratic or the cubic polynomial fitting was used for solving the surface velocity,and the mean square error (∑δ2i)~(1/2) and the max|δi|imum deviation were calculated by the deviation between V(hi) and the actual value of vi,and if the calculated results are within the given range of error,it shows that the fitting is effective. Results show that this static correction method by the polynomial fitting is practical and provides a new way for calculating the velocity of ground surface in the desert area.

Static correction is a key problem to the exploraton in western complex area and complex near surface area,China,and it is also a very complicated problem.The problem of static correction is always the solution of velocity in complex surface,and the more complex of the surface,the more difficult velocity is solved.As there is a great variation in surface geologic condition in Tarim,and the surface is covered with the different sand dune with height ranging from several meters to one hundred meters,in addition,the spreading velocity of wave varies with the height of sand dune,it becomes more important to find the rule of wave's spreading velocity in Tarim.This article brought forward a new static correction method based on many expert's research results about the surface condition in Tarim.The results of application in practice proved a better effect in Tarim.

有限差分法是求波动方程数值解的一种常用方法,但常规的有限差分法难以克服数值频散的干扰.在总结、分析前人工作的基础上,本文对有关技术做了整合和扩展,形成了有限差分的优化算法,主要内容包括高阶有限差分、优化差分参数和通量校正传输(FCT)技术.与常规方法相比,本文方法既提高了波动方程正演的精度又减少了计算量,可广泛用于起伏地形和复杂地下地质构造的波场模拟和分析.通过对煤层模型和BM工区进行正演模拟,验证了本文方法的有效性.

东濮凹陷构造复杂,断块多,岩性变化大,一些地质问题不明,需要高精度3D资料处理来提高资料的纵、横向分辨率,为储层、油藏研究提供精确的依据.针对东濮文明寨地区高精度处理过程中的关键技术进行了大量分析试验,形成了一套适合东濮地区的较为完整的3D高精度地震资料处理流程.实际资料处理表明效果较好.

Emphatical study of artificial control of velocity-depth model is carried Out in the area studied by combining the geological data obtained in the area. Based on the complexity of fracture system in the area, two models are designed for checking the effectiveness of prestack depth shift result to understand the practicality of processing method to the complicated structure. Compared with time shift, the method would be used to solve the imaging problems of complicated fault blocking area with high quality.

为提高胡状集油田胡十二断块沙三段各沉积时间单元沉积微相划分的准确性,在系统取心井单井相研究的基础上,优选并提取了能反映各种沉积微相特征的定量参数,对不同类型的微相进行定量标定.将标定结果输入人工神经网络,应用神经网络的智能功能,并通过自动识别、调整权值,实现对未知沉积时间单元微相的自动识别.用神经网络方法对胡状集油田150多口井95个沉积时间单元进行沉积微相划分,取得了较为理想的结果,避免了仅用测井曲线划分沉积微相的不确定性.