测井曲线剩余变化的分维描述火成岩裂缝发育情况

CHARACTERIZING FRACTURE INTENSITY OF IGNEOUS FORMATIONS BY FRACTAL DIMENSION OF RESIDUAL VARIATION OF LOGS

大庆深层火成岩层段岩性复杂 ,不仅具有从基性到酸性的各种熔岩 ,还包括不同喷发期次的凝灰岩。岩性变化是影响各种测井曲线响应特征变化的最主要因素。裂缝的响应往往被岩性的影响所淹灭。为此从测井曲线中提取分维来描述裂缝发育程度 ,必须考虑岩性的影响。为了消除岩性的影响 ,对分辨率较高且对裂缝反映灵敏的微球形聚焦测井曲线进行滤波处理 ,获得原始曲线与滤波曲线间的剩余变化 ,再从中提取分维 ,从而突出裂缝的影响。实际处理表明 ,从剩余曲线中提取的分数维 。

The lithology of igneous rocks of Daqing area is so complicated that not only basic to acidic lavas were drilled, but also tuffs erupted in different times. The change of lithology is the main factor for the variation of various log responses. The log responses of fractures in the formations are usually glossed over by the lithology effect. The micro spheric focus log (MSFL), which has higher vertical resolution and is sensitive to the fractures in formation, is used to derive fractal dimension. In order to describe the fracture intensity quantitatively, it is necessary to take lithology into account when deriving fractal dimension from logs. After filtering and subtracting the filtered log from original one, the residual variation curve is obtained. The fractal dimension curve is derived from the residual variation curve to reduce the lithology effect, thus the fracture effect will be enhanced. The processing of real log data shows that the fractal dimension curve from residual variation indicates fracture intensity better than from the original logs.