基于路径形态学和正弦函数族匹配的电成像测井缝洞自动识别与分离方法研究

Automatic fractured-vuggy identification and extraction from electric imaging logging data based on an incomplete path opening operation and a sinusoidal database

针对碳酸盐岩缝洞型含油储层,电成像测井方法可以探测得到高分辨率井壁缝洞分布图像,但由于岩性变化、井孔介质非均质性等的干扰以及裂缝间的互相缠绕、黏连使得对裂缝和溶蚀孔洞信息的有效提取仍存在较大阻碍。不完备路径开算法和容忍路径算子对直线或者轻微弯曲结构有良好的适应性,该适应性与结构元素形状的选取无关,而正弦函数族对弯曲结构的匹配度较好。文中将多尺度不完备路径形态学方法和正弦函数族、二阶矩椭圆拟合算法应用于电成像测井电导率图像的处理,提出采用不完备路径形态学算法和正弦函数族智能匹配的裂缝和溶蚀孔洞自动识别和分离方法。首先采用数学形态学中的开闭变换,消除电成像测井图像的干扰;其次,进行不完备路径形态学、密度聚类算法的公式推导和分析,并融合多方向的形态学路径算子、容忍路径算子、含噪的基于密度聚类方法追踪并提取连续或间断的弯曲线状结构;再次,对提取的弯曲线状结构进行改进的Hough变换和正弦函数族匹配,发现Hough变换仅对低角度裂缝的匹配效果较好,而正弦函数族对高角度裂缝及完整度较低的残缝有更高的精确度;还有,使用正弦函数族计算裂缝的相位、振幅和井壁的深度位置信息;最后,对于剩下的溶蚀孔洞,采用二阶矩等效椭圆函数方法进行拟合,获得了孔洞的纵横比。为验证文中提出的算法,对几个数值模型和某油田的碳酸盐岩井的电成像资料进行了处理,成功完成对缠绕的裂缝和孔洞的分离过程,验证了所提出算法的有效性和适应性,为碳酸盐岩缝洞型含油储层的精细评价提供了实用方法,有助于提高对储层缝洞分布特点的认识水平。

By applying electric imaging logging equipment for different kinds of fractured-vuggy carbonate oil reservoirs,we can get high resolution images of the borehole wall.However,it is hard to acquire the information of the fractures,solution pores and cavities accurately on the account of the lithology distribution randomness,the media heterogeneity around the borehole and the intertwining and adhesion of fractures.Based on the incomplete path opening and tolerance operators that remain flexible enough to fit rectilinear and slightly curved structures since they do not depend on the choice of a structural element shape and the advantage of a sinusoidal database that can fit the fractures precisely,this paper proposes a new method to intelligently identify and extract discontinuous fractures solution pores and cavities from the original electric logging image data by using multi-scale incomplete path opening and tolerance operators,a sinusoidal database and a second-order moment ellipse fitting method.First,the opening and closing operation of mathematical morphology is adopted to eliminate the noise of the electric imaging logging data.Then formulas of incomplete path opening and a density clustering method are deduced and analyzed.The incomplete path opening parameter sets and tolerance operators in different directions are applied to trace and separate fractures and the density-based clustering of applications with noise is introduced to classify these separated parts of fractures that are in continuous or intermittent bending linear structures.After the comparation of results of bending linear structures fitting in a Hough transform and a sinusoidal database,we find that the Hough transform is only appropriate to match the low angle fractures while the sinusoidal database method is more accurate for high angle fractures or in fragmentary condition.Apart from that,we can get the phase,amplitude and depth information of these fractures by the sinusoidal database method.Finally,the second-order moment method is used to determine the equivalent ellipse of the remaining vugs and the vertical-horizontal ratios of vugs are obtained.In order to illustrate the application of the proposed method,examples of numerical simulation data and oil well field data have been tested.According to the result,intertwining fractures and vugs are separated successfully,which demonstrates the effectiveness and adaptability of our method in application of electric imaging logging data.So the proposed method offers practical support for the precise evaluation of fractured-vuggy carbonate oil reservoirs and helps to raise the level of recognition to the distribution of fractures and vugs of the target layers.