利用反射纵波评价裂缝倾角的模拟实验研究

Experimental Investigation on Evaluation of Dips of Fracture Using Reflected Compressional Waves.

声波全波列测井中的反射纵波可以用来评价高角度裂缝和对井周附近地质结构进行成像。目前的研究主要侧重于直接从波形资料处理出发计算裂缝的位置和倾角 ,其可靠性和准确性无从评价和校验。文中采用模拟实验的方法记录了倾角为 6 0°～80°范围内的 8种倾角裂缝的反射脉冲纵波波形 ,自行推导了反演裂缝倾角的公式 ,结合波场分离技术对实验测量波形数据进行了处理 ,计算出的裂缝倾角与实际值具有良好的一致性。本文结果表明 ,利用至少

The reflected compressional waves of the full waveform acoustic logging can be used to evaluate fractures with high dips and image the near borehole geological structure. At present, researches mainly focus on determining the locations and dips of the fracture directly from processing waveform data, so the reliability and accuracy are uncertain. In this paper, physical simulation has been carried out on eight types of reflected compressional waves from fractures with dips ranging from 60° to 85°,and corresponding inversion formulas for frature dips are deduced. Based upon the measured waveform data, the inversed fracture dip values calculated with inversion formula and wave field separating technique are in good agreement with that measured with protractor.It is shown from the paper that the fracture dips can be accurately inversed by using at least two reflected compressional waveforms recorded at different depth points.