页岩气地震勘探数据采集参数选择的研究

我国页岩气重点开展区域为南方海相沉积地层,地震地质条件相对复杂,数据采集难度较大。贵州凤冈某页岩气勘查区块,属典型的喀斯特低山地貌,地形起伏大,地震施工困难,同时寒武系下统牛蹄塘组页岩层埋藏较深,反射波能量较弱,原始资料信噪比偏低。参考邻区地震勘探经验,采用二种方法论证野外施工参数:一是在勘探区选取论证点设计物理模型进行理论计算;二是以勘查区内向斜部位设计地质模型进行正演模拟求取。在此基础上通过进行不同岩性、井深、药量等激发接收参数的试验,确定了该区块的野外施工方案。该区页岩气地震勘探野外施工参数的选择方法,有效保障了其页岩气地震勘探效果。

A Study on Parameters Selection in Shale Gas Seismic Prospecting Data Acquisition

The key targets for shale gas exploration is in the southern China marine sedimentary strata, seismic-geologic condition there is relatively complex, seismic prospecting data acquisition is rather difficuh, A shale gas prospecting block in Fenggang, Guizhou belongs to typical karst low mountain relief with undulating topography, thus difficult in seismic prospecting operations, also rather deep lower Cambrian Niutitang Formation shale buried depth, weaker reflection energy, rather low original data S/N ratios. Neighboring area seismic prospecting experiences have been consulted, through two methods to demonstrate field operation parameters： one is choosing demonstration points in prospecting area to design physical model carry out theoretical computation; another is in prospecting area syncline part to design geological model carry out forward simulation. On this basis through tests of shooting and receiving parameters including different lithology, well depth, powder charge etc. have determined field operation scheme. The selection method of shale gas seismic prospecting field operation parameters has effectively guaranteed prospecting results.