特低渗透砂岩储层裂缝特征及其常规井识别方法

由于各种因素的控制,特低渗透砂岩储层裂缝倾角、密度、规模、开度、孔隙度、渗透率等表现出与碳酸盐岩储层裂缝不同的特征,不同特征的裂缝对常规测井曲线的响应不一样,结合实际的地质特征,分析不同形态和发育程度的裂缝对常规测井曲线形态的响应特征,根据岩心和成像资料建立其响应模式,以此指导非取心井和非取心段特低渗透砂岩储层的裂缝识别。水平裂缝和网状倾斜裂缝对常规测井曲线响应相对明显,可以根据曲线特征直接识别;而高角度裂缝响应较差,但经过特殊处理可以放大裂缝对常规测并曲线的响应,以此来识别高角度裂缝。该方法在QX构造须二段特低渗透砂岩储层应用效果良好,并进一步在统计分析的基础上得出:高度小于30cm的裂缝不容易识别,大于30cm的相对较容易识别;裂缝的开度越大、孔隙度越高、渗透率越高,识别效果较好,反之,开度小、孔隙度低、渗透率低的裂缝识别效果较差。

The Fracture Characteristics of an Extra Low-Permeability Sandstone Reservoir and Its Identification Method with Conventional Well Logging

Fractures of an extra low-permeability sandstone reservoir present different characteristics against those of a carbonate reservoir in dip, density,scale,opening,porosity and permeability,etc.because of different factors.Fractures with different characteristics have different re- sponses in conventional logging.Combining practical geologic characeristics with analysis of the response characteristics of fractures with different shape and development process to the conventional logging,the response modes are established according to the coring and imag- ing data,which are used to guide fracture identification in non-coring wells or intervals.As the responses of horizontal fractures and netty dipping fractures are comparatively obvious to conventional logging,they can be identified directly through curve characteristics,while high angle fractures can be identified through the magnified response after special processing because of their poor responses.The method has gained good application effect in an extra low-permeability sandstone reservoir in Xuer section of QX structure.