基于正演模拟的最大似然法火山岩有效裂缝识别及预测

针对准噶尔盆地西北缘车排子凸起火山岩有效裂缝识别和预测不清的问题,建立了3种断裂的地震正演模型,对比了基于相干、曲率和最大似然属性火山岩裂缝的识别效果,并基于最大似然方法,利用岩心和成像测井对有效裂缝的微观刻度三种方法对,将有效裂缝发育密度定量化。研究表明:最大似然属性火山岩断裂预测精度更高,对断裂发育带内裂缝发育细节成像效果更好;裂缝走向与现今最大主应力方向一致的高角度构造裂缝发育区更有利于火山岩油藏的形成;预测4个火山岩有效裂缝发育区的展布面积约为76 km²,可以作为下一步勘探的有利区。研究技术能够对火山岩有效裂缝进行精细刻画及预测,对火山岩有利目标的优选具有指导意义。

Identification and Prediction of Effective Fractures in Volcanic Rocks by Maximum Likelihood Method Based on Forward Modeling

To address the problem of unclear identification and prediction of effective fractures in volcanic rocks of Chepaizi Uplift on the northwest margin of Junggar Basin, a seismic normalization model was developed for three types of fractures to compare the effects of identifying volcanic rock fractures with coherence, curvature and maximum likelihood attributes, and to quantify the density of developed effective fractures based on the maximum likelihood method by using the modeling technology of micro-scaling effective fractures by core and imaging logging. It was found in the study that the maximum likelihood attribute method could more accurately predict the volcanic fractures and achieve better imaging effect on the details of fracture development in the ault development zone; the high-angle tectonic fracture development zone where the fracture orientation was consistent with the current maximum principal stress direction was more favorable to the formation of volcanic reservoirs; it was predicted that the distribution area of the four effective fracture development zones of volcanic rocks was about 76 km², which can be used as a favorable area for further exploration. The technology in the study can accurately characterize and predict the effective fractures in volcanic rocks, which is of guiding significance to the optimization of favorable targets in volcanic rocks.