Abstract: The deeper the difficulty in exploration and development is,the more the demand of drilling operation for reservoir prediction accuracy before drilling is.The depth of reservoir,the thickness of reservoir and prediction accuracy of space distribution play decisive role for drilling efficiency and successful rate,especially for horizontal well productivity.The structure of W oilfield is a subtle trap with very low amplitude.Moreover,poor data quality of target layer influenced by shallow layer gas leads to big difficulty in prediction before drilling of deep horizontal production well.By a series of techniques such as correction of shallow layer gas,establishment of accurate speed model and conversion of depth domain and earthquake retrieval property body from time domain earthquake data body,and so on,the prediction result of space distribution in oilfield reservoir is obtained.Optimization before drilling and researches during drilling is done on that basis.Therefore,drilling in horizontal section is implemented successfully,and both drilling efficiency and productivity of horizontal production well are improved obviously.