火山岩油藏地层渗透率评价研究

火山岩油藏裂缝普遍发育,对地层渗透率的贡献具有决定性作用。通过对石炭系火山岩11口探井及评价井测井、试井、试油试采等资料的综合分析评价,认为测井方法得到的渗透率往往与生产动态不符,不能直接用于油藏开发评价。基于不稳定渗流原理,通过试油试采等动态方法反算,得到了井段平均渗透率;进一步结合地层有效厚度等数据,计算了储层渗透率。结果表明:测井渗透率与孔隙度具有较好的相关性,主要反映了基质的特征;动态方法得到的储层渗透率是测井渗透率的几十倍,且能够反映裂缝控制下的地层实际渗流能力。据此将火山岩储层分为双重介质型、裂缝型、孔隙型三种基本类型。结合具体油藏分析认为,双重介质型是火山岩油藏最主要的储层类型。

Study on the Formation Permeability Evaluation of Volcanic Reservoir

Fracture develops generally in volcanic reservoir, and plays a decisive role to contribute formation permeability. By means of comprehensive analysis and evaluation of the data from logging, well test and production test, which come from 11 exploratory and appraisal wells of carboniferous volcanic reservoir, think of that the formation permeability obtained by logging interpretation does not match the actual production performance. So the logging permeability cannot be directly used for the development and evaluation of volcanic reservoir. Based on the principle of unstable seepage flow, the interval average permeability is obtained by inverse calculation through fitting the dynamic characteristics of oil production test. The formation permeability can be obtained by conversion of effective thickness. The results show that the logging permeability and porosity has a good correlation, mainly reflects the character of matrix. The formation permeability obtained by dynamic methods, which can reflect the actual seepage ability of volcanic reservoir under the control of fracture, is of several times of logging permeability. Volcanic reservoir can be divided into three types: double medium type, fractured medium type and pore medium type, which are based on the classification basis proposed by the characteristics of porosity and permeability of volcanic reservoir. The double medium reservoir is the main reservoir type combined with analysis of M reservoir. Based on the formation, fluid and pressure parameters of typical reservoir, the productivity of unit thickness of each type of reservoir are calculated separately. The results show that the capacity of double medium type is about 10 times of that of fracture medium type, and is several times of that of pore medium type.