VSP测井在大型陆相沉积煤田勘探中应用效果

Application Effect of VSP Logging in Large-scale Terrestrial Deposited Coalfield Exploration

在我国煤炭资源中,中生代陆相煤田所蕴藏的煤炭资源占有重要地位,尤其是早—中侏罗纪陆相煤田,已探明煤炭资源总量占我国探明煤炭资源总量的63%,煤田规模大都为大—超大型,煤质优良。该类煤田沉积环境复杂,具有煤层层数多、厚度变化大、煤层稳定性和连续性差、合并及分叉点多,勘探难度较大。为此,在鄂尔多斯市东胜区西部勘探项目中采用了包括钻探、二维地震、综合测井、VSP测井、地质与水文工程地质填图等在内的综合勘探手段,取得了良好的地质效果,其中VSP测井在该勘探区的应用,不但准确提取了二维地震资料的时～深关系,提高了时—深转换精度,而且使声波测井资料得到了有效校正,地震带井约束波阻抗反演技术处理更合理,解释结果更可靠。综合利用VSP和声波测井资料进行交互速度分析,提高了地震资料对目的层的解释精度,为大型陆相沉积煤田的岩煤层对比解释提供了丰富的地质信息。

Coal resources containing in the Mesozoic terrestrial deposited coalfields occupy an important status in the country,especially early-middle Jurassic terrestrial coalfields,their proved total coal resources account for 63% the nation＇s total of this category.Coalfields are mostly large to ultra-large scales with good coal quality.This kind of coalfields have complex depositional environment,numeral coal seams,variable thicknesses,poor coal seam stability and continuity,merged and bifurcated very often,thus make difficulties in exploration.Therefore,integrated exploration means including drilling,2D seismic prospecting,integrated well logging,VSP logging,and geological,hydrogeological,engineering geological mapping have been used in the western part exploration project in Dongsheng District,Ordos City,and obtained good effect.In which,the application of VSP logging in the project is not only picked up correct time-depth relation in 2D seismic data,improved time-depth conversion precision,but also effectively corrected acoustic logging data,more reasonable seismic belt well constrained impedance inversion technical processing,and more reliable interpretation.Comprehensively using VSP and acoustic logging data to carry out interactive velocity analysis,will improve seismic data target interpretation precision,and provide large-scale terrestrial deposited coalfield rock and coal seam correlation with abundant geological information.