1、河流相砂巖儲層地震響應特征與識別技術研究        河流相砂體多以砂泥巖互層形式沉積,在砂、泥巖薄互層儲層預測技術研究中,常因地震資料的“假象”或“陷阱”而造成解釋或預測結果的錯誤。為此,本文利用模型正演技術,對具有典型河流相砂體沉積特征的地震地質模型進行模型正演計算,研究和分析這些模型的地震反射特征(包括振幅、頻率、相位等特征),從理論上探討入射子波類型、主頻、薄互層厚度、薄互層的互層數等對地震反射特征、頻譜特征的影響規律,為實際薄互層地震資料的處理解釋提供重要的依據,而且對我們定性或定量求取薄互層組中各單層

2、厚度或薄層組的厚度、預測薄儲層的空間展布規律具有現實的指導意義。各向異性在地層層圈中是廣為存在的,砂泥巖中由于垂直地層傳播的低速波和沿地層傳播的高速波的速度差異而呈橫向各向同性。在傾斜各向異性序列中,速度隨射線角度變化產生的數值改變對地下反射界面的旅行時產生巨大影響,即導致視速度異常。通過運用交錯網格有限差分的方法,本文對TI介質各向異性對稱主軸傾角變化情況下,彈性波場的地震響應特征進行了正演計算,以分析等效的砂、泥巖薄互層非水平沉積時儲層的各向異性響應特征,從而為指導地震資料處理與解釋提供理論指導。最后,本文對扶楊油層實際地震資料應用高分辨率的地震資料處理、解釋和反演方法進行成果解釋。結果顯

3、示,所用方法對扶楊油層河道砂體的識別能力得到了很大的提高,特別是廣義S變換法頻譜分解技術的應用,較大的提高了河道砂體成像的分辨率In recent years, along with the deepening of the oil-gas exploration development, some collected strap of oil and gas has been found in the river way enclosed by sandstone lithology in many basins of our country and industrial oil has b

4、een obtained. The combination of mid-top oiliness in Chang-heng area of Da qing city has been put into operation for 40 years with the steady production of 5000×104t. There have abundant oil resources as it is located among the sunken area of Qi jia-Gu long and San-zhao. The Fuyang oil reservoi

5、r stratum of these area is mainly composed by delta diffluence plain river way sandstone and delta former underwater diffluence plain river way sandstone, and these river ways interlace each other with reticulation and make sand body overlapped and connected in planes so that a good reservoir format

6、ion space will be provided for a large area of lithological oil and gas.The sandstone of Fuyang oil reservoir overlaps and connects with each other because it transfers and swings frequently in the time of sediment, and the monolayer of these sandstone is so thin at 15 m, therefore identifying the r

7、iver way and finding the thicker river way sandstone is the key of exploration for Fuyang oil reservoir and a difficult problem as well. This paper has been done in resolving the following problems:(1) A geology model has been established that describes reservoir sediment and distribution on the bas

8、e of characteristics of reservoir geology in the research area. Through the modeling technology and on the assumption that the condition of underground geology is known, the fundamental of seismic kinematics and kinetic are used to calculate the response from the geology model which has been given.T

9、he geology models constructed in this paper include: fluvial folded sandstone model、sediment sandstone model in different time and sand model with different sediment character. Through the analysis of these models we can see that the sand stone in different periods has different imaging character fo

10、r its different distributional manner. So we can conclude that the major factor influencing seismic imaging is configuration of sandstone overlapping and sandstone velocity. At the same time, we use the method of two steps finite difference to resolve sound wave equation to model the seismic geology

11、 on the base of actual seismic date that has been interpreted. We select the adopted modeling parameters and observation system parameters to obtain seismic response, using post stack time excursion and pre-stack deep excursion to revise the location. To compare the answer with actual seimic date so

12、 that the actual date is true or false can be judged and estimated.(2) The sandstone thin bed layer presents transverse isotropy for the difference between low velocity wave spread vertically upon the layer and high velocity along the layer. However, the axis of medium will not be vertical when the

13、lay rots for draping and up rushing. So the layer is not horizontal but strikes upward. In this case, the difference will be more obvious for the difference of velocity of vertical and horizontal layer because of anisotropy. In the slope anisotropy, the numerical value of velocity changing with radi

14、al angle will affect profoundly the travel time from reflecting layer underground, i.e. apparent velocity abnormity.To analyze the influence of sandstone reservoir imaging that anisotropy makes, we use innerving girding finite difference to model anisotropy imaging of sandstone. We can see that the

15、reflected elastic wave in TTI media include qP wave、qSH wave、qPSV wave、qPSH wave, the transmit wave include P wave、SH wave、SV wave and divert wave; axis of wave front deflexed, the mini travel time of qP wave excursed, this will cause disturbance of geology construction in actual seismic imaging. Si

16、multaneously, we analyze the influence of Thomsen anisotropy parameters to seismic wave travel, and the influence is obvious when anisotropy parameter to elastic wave aversion distance changes, especially when the angle of incidence of reflected wave is bigger than critical angle in the far distance

17、. So the fortification of the phase appears in the far distance on the seismic section. Further more, the influence that Thomsen parameters on vertical and horizontal wave are not the same, the influence on vertical wave is weaker than horizontal wave.(3) In recent years, high differentiate seismic

18、explorations of 2D and 3D have been done in Chang-yuan, the technology of 3D seismic exploration complex ground surface condition is mature, which offers a information base to take a fine forecast and study of reservoir of Fuyang oil layers. On the base of these, we take the technology of compensate

19、 radiation and absorption of sphere in the field of time、frequency and space to improve the resolution. Utilizing these technologies, we have eliminated the effect of excitation in the near ground surface、frequency difference and false reflection and improve the resolution of datum. Using the method of restrict reversion, and basing on the geology model, we take the way of synthetic seismic record and wave impedance reverse to demarcate thin layer and the arithmetic model pre-select iterative disturbing. By modifying and updating the