辽西葫芦岛东部表层结构调查及速度建模

Surface Survey and Velocity Model Building in Eastern Huludao of Western Liaoning Province

针对国家深部探测项目地震数据采集及表层速度结构模型建立的需求，在辽西葫芦岛东部二维地震勘探工区开展了表层结构调查工作。该地区地表起伏大，表层结构复杂，低、降速层厚度和速度多变，静校正问题突出，做好表层结构速度建模工作成为该区地震勘探的关键问题之一。由该工区实验点多种表层调查方法对比实验结果，确定了该工区表层调查工作方式：以井中微测井方法为主，在满足小折射地表条件的区段辅以成本较低的小折射方法作为补充；同时对留作微测井的生产井进行岩性录井。基于以上方法，分析了表层调查野外施工的难点和对策，确定了微测井采集参数。本次表层调查工作测线长度16．9 km，设计了8口微测井，根据微测井解释成果得到如下结果：该测线表层分2～3层；低速层厚度为1．68～4．33 m，速度为350～1000 m/s；降速层厚度为5．00～12．00 m，速度为1000～2800 m/s；高速层主要为岩性致密的花岗岩，速度为2800～4900 m/s。根据井中微测井结果及层间相似系数，建立了该测线的表层模型，设计激发井深13．00～15．00 m，并获得静校正量数据。

To meet the demands of seismic exploration acquisition and near-surface velocity modeling in deep exploration in China,surface survey was carried out in 2D exploration area of eastern Huludao in western Liaoning. The topography of this region is undulating, surface structure is complex, the thickness and speed of low-velocity layer and slow-down-velocity layer is unstable, leading to a prominent static correction problem.Therefore,it is a key problem to complete the j ob of near-surface modeling in this region.By comparing the different results from a variety of methods,we choose following surface survey methods.Uphole survey method is given priority;then refraction method, which costs lower,in the region that meets the refraction surface conditions;at last,as a complement, lithology log method at production well reserved for uphole survey.With these methods,we analyze the difficulty and countermeasure of surface survey and determine the parameters of field construction.In this surface survey,along the profile of 1 6 .9 km,8 loggings is laid out.According to the micro log interpretation results,the near surface is of two or three layers;low-velocity layer thickness is 1.68 4.33 m with a speed about 350 1 000 m/s;the thickness of low velocity zone is about 5 12 m,whose speed ranges from 1 000 to 2 800 m/s;the high speed layer is pyknotic granite,whose speed is 2 800 4 900 m/s.According to the results of micro logging and the coefficiency similarity between each layer, the authors establish a near-surface model,suggest the depth of shot hole,and obtain the statics data. These works effectively guide the design of field seismic acquisition,provide the reliable basis for data processing,and supply a reference to the surface survey in other region.