塔里木盆地塔河油田奥陶系数字岩心图像中生物扰动的定量表征*

生物扰动对塔里木盆地塔河油田奥陶系碳酸盐岩“基质储集体”储集性能的改造效应具有重要影响。以塔河油田奥陶系岩心为研究对象,利用Adobe^® Photoshop^® CS6软件提供的生物扰动数字图像分析软件包,对岩心数字图像中生物扰动区域进行了识别和定量表征。结果表明: (1)在生物扰动数字图像分析软件包提供的方法中,“相似像素选择法”和“魔棒法”是对生物扰动识别与定量表征最为有效的方法,但二者适用范围不同;(2)“相似像素选择法”适用于生物扰动程度较大,单个形体相对较小且离散度相对较高的情况:当生物扰动充填物和围岩基质边界对比度较大时,应用“选取相似”操作效果最好;而当生物扰动充填物和围岩基质边界对比度较小时,应用“色彩范围”操作识别效果最好;这2种操作都仅能执行1次;(3)“魔棒法”对于识别生物扰动区域形体大而分布连续,且充填物颜色不同的情况具有独到优势;该方法可以通过多次重复操作以及调整“容差”来提高生物扰动区域与围岩基质的识别度。该研究对从生物成因角度解释碳酸盐岩“基质储集体”的非均质性与分布规律、实现增强储集性能生物扰动属性表征、丰富海相碳酸盐岩储集层地质学理论、指导该类油气藏远景勘探和储量计算以及选择合理的开发方案等具有重要意义。

Quantitative characterization of bioturbation based on digital image analysis of the Ordovician core from Tahe Oilfield of Tarim Basin

Bioturbation has a great influence on the carbonate reservoir properties of “matrix reservoir” of the Ordovician in Tahe Oilfield of Tarim Basin. With the help of Bioturbated Digital Analysis Images Package of Adobe^® Photoshop^® CS6,the study was carried on the core of the Ordovician from Tahe Oilfield to identify and estimate quantitatively the area that was bioturbated in the core digital image. The results show that: (1)Within the methods of Bioturbated Digital Analysis Images Package,“Similar Pixel Selection Method” and “Magic Wand Method” are the most effective to identify and estimate quantitatively bioturbation and have different ranges of application. (2)The Similar Pixel Selection Method is suitable for the samples with high bioturbation,small size and high diversity. When there are considerable differences between the infill of bioturtation and the surrounding rocks,“Select Similar” is the best way to estimate quantitatively the bioturbation. Otherwise,when there are just little differences between the infilling and host rocks,“Color Range” is the best way. (3)Magic Wand Method has an advantage on the samples with large size trace fossils and good continuity as well as different color of infilled material. By modifying “Tolerance”,Magic Wand Method will increase the degree of recognition between the bioturbated area and host rock. This research makes a convincing explanation about heterogeneous and distribution of “matrix reservoir” of carbonate rocks in the perspective of biogenic,and has a great significance on fulfilling the characterization and interpretation of those bioturbation enhanced reservoir capacity in carbonate rocks,enriching geologic theory of carbonate reservoir,guiding the hydrocarbon exploration of the bioturbated reservoir,calculating reserves and selecting the best plan of the development of oil and gas fields.