基于孔隙结构的酸性火山岩储层流体识别方法研究

酸性火山岩由于成岩矿物类型多样,孔隙结构复杂,电阻率普遍较高,应用常规的中子-密度测井曲线交会和电阻率的高低已经不能判断储层流体性质.在天然气的测井响应特征分析基础上,应用三孔隙度组合、横纵波时差比值、核磁共振及综合参数识别流体性质.应用结果表明这些方法只能识别含气储层,对于气水同层的识别效果并不好.电阻率对储层流体性质变化反映灵敏,但是对于酸性火山岩储层并不如此.从储层微观孔隙结构入手,对火山岩储层电阻率影响因素进行研究,表明孔隙结构复杂是酸性火山岩电阻率普遍较高的原因之一,在此基础上,研制了基于孔隙结构的流体性质逐步判别法.应用本文的方法,对徐深气田49口井流体性质进行判断,经69个层试气验证,识别准确率达94.1％,提高了近15个百分点.

A study on the fluid identification method of acidic volcanic reservoirs based on the pore structure

Because of various types of minerals, complex pore structure and generally high resistivity of volcanic reservoir, using conventional neutron-density-logging curve intersection and high-low of resistivity to identify reservoir fluid type is not viable. Through the analysis of characteristics of natural gas logging response, the paper uses porosity combination,the ratio of transverse wave and longitudinal wave,nuclear magnetic resonance and integrated parameter to identify fluid type. Results show that these methods can only identify gas-bearing reservoir, and the result of identifying reservoirs which contain gas and water is not good. Resistivity is sensitive to the changing of reservoir fluid types, but is not so for acid volcanic reservoir. Starting from the microscopic pore structure of reservoir, the paper studies the influence factors of volcanic reservoir resistivity. Results show that complicated pore structure is one of the reasons of high resistivity of acidic volcanic reservoir. On this basis, the paper develops the fluid type gradual identification method based on the pore structure. Using this method, the paper identified the fluid type of 49 wells in Xushen gas field. Through the test of 69 layers, identification accuracy is 94.1%. The accuracy has increased nearly 15 percent.