Study On High Resolution Processing Method For Stoneley-Wave Of Array Acoustic Logging

With the gradual development of exploration and exploitation for oil and gas, it is urgentlyrequisite to determine and evaluate thin beds. Therefore, high resolution processing of well logsmust be done so as to enhance the accuracy of evaluating thin beds. Cross-dipole array acousticlogging has been applied widely in oil fields at present. Current array waveform processingtechniques pursue accuracy of each wave component's slowness, while neglect its verticalresolution. In addition, the applied result of current high resolution processing methods forconventional sonic log is not completely satisfactory though it has acquired some progress.Base on character of stoneley-wave of the monopole full waveform, the arrival ofstoneley-wave has been picked with the method of energy ratio between the long window andthe short window by the square of the amplitude envelope of waveforms. Based on the globaloptimization characteristics of genetic algorithm and the principle of slowness calculating withslowness time coherence, a new integrated processing technique of array acoustic data isproposed with slowness time coherence and genetic algorithm in the paper. The correlationfunction reflecting waveform similarity in slowness time coherence is used as the object functionof genetic algorithm, then, maximum of object function is found with genetic algorithm, finallythe wave arrival time and slowness values corresponding to the maximum value of objectfunction are gotten. The integrated method is not affected by the steps of wave arrival time andslowness, and global optimization solution is found with less computation in the range of givenslowness and wave arrival time. After the stoneley-wave slowness between the shortestsubarrays(0.5 feet)with the integrated method is calculated,and the shortest subarrays arecombined into common-source subarrays and common-receiver subarrays, respectively, highresolution stoneley-wave slowness will be obtained. Stoneley-wave slownesses calculated withcommon-source subarrays and common-receiver subarrays at the same depth interval areaveraged to acquire high resolution stoneley-wave slowness corrected for borehole effectCrossed multiple array acoustic data processing of eight wells in Daqing Oil Field is done,and the processing result is compared with that of commercial software eXpress, and goodagreement has been achieved. It shows the proposed method can be applied to slownessprocessing of array acoustic data with good accuracy.