Velocity Field Research And Its Application In The East Of Liaohe Area

In recent years, with the deepening of the exploration degree, petroliferous basin exploration work from the original finding structural reservoirs gradually turned to find low amplitude structural reservoir and concealment of complex lithologic reservoir, the interpretation of seismic data and the accuracy of structure map has put forward higher requirements, and also the underground seismic wave velocity in a higher accuracy requirements. Studying the speed parameters of seismic wave has been an important part of the seismic exploration, and obtaining the accurate velocity parameters plays an important role in seismic data interpretation and improving the accuracy of structure map. This paper based on velocity spectrum data analysis in shuangdong area, and the use of logging speed high density longitudinal control constraints to establish the accuracy of velocity field, and provided accurate velocity for studying low amplitude、 lithologic traps and improving the precision of the structure study in shuangdong area.Although the use of conventional velocity mapping also can reflect the underground structure, it is difficult to accurately implement objective layer configuration and structural highs in real position. Especially when the region of complex structure、large stratigraphic dip、numerous faults and speed of transverse and longitudinal changes in the larger, the use of conventional velocity mapping method for time-depth conversion, will often lead to erroneous results and increase the exploration risk. Therefore, how to scientifically and rationally calculate the seismic wave velocity and to obtain an accurate structural map, is our unremitting efforts in the direction.Variable velocity mapping technology is applied along the layer coherent layer velocity inversion method to obtain the accurate layer velocity, after using the mapmigration method conducted more accurate time-depth conversion for the time structure map, and the main results is depth contour map. It is an effective method to study low amplitude structure and complex fault block.Shuangdong area is located in the largest oil and gas source sag of the Liaohe depression-qingshui sag, it has sufficient oil source conditions, this area ascertain rate is low, to explore the large amount of resources, potential is tremendous. The area is controlled by west and east side from the central bulge two source, deposition condition is complex, multi-layered sand body development, lateral sand body changes, at the same time, the district is deeper, reservoir physical property is the main control factor to restrict reservoir, and brought very great difficulty for fine prediction of reservoir and comprehensive evaluation of reservoir quality. The article is based on the understanding of the concept of several seismic velocity, and comprehensively analysis the main factors of effecting seismic wave velocity, and based on analysis and comparison of the calculating principle and method of the Dix formula method and control method, combined with the actual geological conditions of shuangdong area, and determined compliance with the area field and strengthen the fine study on seismic velocity. By analyzing stack velocity spectrum and drilling data, combined with the geological structure characteristics of this area, and select the appropriate speed calculation method to improve the calculation precision of the layer velocity and the average velocity, and complete the subsurface reflection layer depth contour, make clear the hydrocarbon reservoir types in the area、oil gas distribution and the main control factors, and provide technical support for oil and gas exploration of shuangdong area.This paper is based on the regional geological background and on the basis of previous studies, using the velocity field, through the variable velocity mapping technology, completed the depth structure map of the main purpose layer and prediction of target layers of sandstone and mudstone content, and points out the favorable exploration target. The work mainly in the following aspects:1. This paper discusses some common seismic wave velocity definition, such as the mean velocity、layer velocity、root mean square velocity and superimpose velocity, and summarizes the relationship between them.2. It analysis the main influence factors of the seismic wave velocity, and explains the necessity of establishing velocity field.3. It summaries the traditional average velocity field method, analyzes their applications conditions and defects.4. It reviews the method principle and main steps of the variable velocity mapping, put forward several problems needing attention, namely to improve the precision of seismic stack velocity、layer velocity reasonable calculation and correction、spatial grid、selection of the seismic datum and average velocity volume correction.5. using geological、geophysical prospecting and logging combined with comprehensive research method divide stratigraphic for the purpose of section of shuangdong area, based on fine formation correlation product fine synthetic seismogram and complete calibration, in the condition of the good horizon and fault, through the explanation of the layer of data and the average velocity extracted from velocity field conduct time depth conversion and draw depth contour, the depth contour through the method in high agreement with the actual well depth.6. Layer velocity of target zone from the velocity field, and forecast sand and mudstone content of the objective layers.