大北气田属于裂缝型致密砂岩储层，裂缝发育程度直接影响了天然气的发现，以及后期产能建设，因而对裂缝的正确描述意义重大。目前一般用裂缝密度描述裂缝的发育程度，但该方法存在着固有的局限性：只能应用于野外露头、岩心和成像测井方面。针对井下裂缝描述，岩心先天具有量少、代表性差的缺陷，而利用成像测井资料解释裂缝，对资料、人员要求高，解释结果随机性相对较大，并且成像测井成本高，资料缺乏。因此，通过实践，在裂缝的研究过程中，引入了分形学的概念。根据分形学的定义，利用常规测井资料，结合大北气田裂缝在常规测井曲线上的反应特征，利用R/S 分析对大北地区目的层段裂缝发育程度进行了定量分析。经钻井、岩心等验证，效果良好，表明在大北气田，应用R/S方法对岩心进行定量描述是一个行之有效的方法。

The Dabei gas field as a tight sand reservoir is controlled by the fracture development which directly affects the discovery and deliverability of the natural gas. The appropriate way to describe the fracture is very important. At present, the fracture spacing is a general method to describe the fracture degree, but its shortage is only suitable for the description of outcrop, core and FIM. A few of drill cores and poor representativeness can not illustrate the fracture distribution in well bore. The fracture analysis by image data requires the skillful analyst and the image data, with the random interpreted conclusion, the high expense of the image data, and absence of image data. So, the concept of fractal is proposed in the research of fractured reservoir. According to fractal concept, the data of conventional logging suite were used, in combination with the logging feature of fracture in the Dabei gas field. The fracture in the goal layer of Dabei area is quantitatively described by the method of R/S. The result which was tested by the data of cores and drilling available, suggests that the method of  R/S  is feasible to quantitatively describe the fractures in the Dabei gas field.