利用VSP多波资料预测地层深度及油气属性

油气勘探开发过程中须要对钻前地层信息进行预测，VSP技术是较常用的预测方法。传统的VSP方法仅利用上、下行纵波来预测钻前地层深度，预测精度有限，且未与目的层油气属性相结合。由此提出一种利用VSP多波信息预测地层深度及油气属性的新方法。该方法充分利用VSP丰富的波场信息，首先在垂直地震剖面中同时追踪与目的层相关的多组地震同相轴，然后将追踪所得到的离散函数根据不同交汇点进行分组，再分别求解超定方程组，进而利用统计加权的方法得到最终的预测结果。该方法减少了预测结果的偶然性，大幅提高了地层深度预测的精度。在获得准确地层深度数据后，再利用纵、横波的波形信息差异来识别和预测油气属性特征。通过中国西部地区2个VSP项目实例验证了该方法的应用效果。

Prediction of strata depth and hydrocarbon attributes by using VSP multi-wave data

Prediction of pre-drilling strata information is necessary in the process of oil and gas exploration and development. VSP technology is a commonly used prediction method. Traditional VSP method only uses upgoing and downgoing waves to predict the depth of pre-drilled strata,and the accuracy of the predicted stratigraphic depth is limited. So far,few scholars have studied attribute prediction methods based on VSP data. A new method for predicting formation depth and hydrocarbon attributes by using VSP multi-wave information was proposed. This method makes full use of the abundant wave field information of VSP. Firstly,the multiple events related to the target layer were tracked in the data,and according to the tracked result,the discrete function groups were built,and the overdetermined equations were solved separately. Then the statistical weighting method was used to obtain the final prediction depth. This method can reduce the uncertainty of the prediction results and greatly improve the accuracy of the formation depth prediction. After obtaining accurate formation depth data,the differences between compressional wave and shear wave were calculated and used to predict the hydrocarbon attributes. The practical application effect was proved by two examples of VSP projects in western China.