低阻油层识别新方法及其应用

低阻油层是一类电性上比较特殊的油气层，在测井结果中不易与水层区分，它作为一类重要而特殊的油气层已经成为油田开发中后期增储上产的重要对象。因此，深入分析低阻油层成因，并采用有效的方法识别低阻油层具有重要意义。通过全面分析束缚水质量分数、岩性、孔隙结构、黏土矿物成分、地层水矿化度及特殊导电矿物等因素，认为砂岩细粒成分质量分数是M地区某油层低阻的主要影响因素，分析了砂岩细粒成分质量分数对储层、物性、孔隙发育、束缚水及黏土矿物质量分数的影响．提出了一种砂岩细粒成分质量分数与电阻率交会图结合支持向量机识别低阻油层的新方法。编制了砂岩细粒成分质量分数与电阻率交会图，由此确定了低阻油层的砂岩细粒成分质量分数和电阻率临界值。通过支持向量机方法对已知含油气状况的样本点进行了重新识别，并对M地区某低阻油层进行了判别。结果表明，该方法显著提高了低阻油层的识别能力．展示出良好的应用前景。

New method for identifying low resistivity reservoirs and its application

Low resistivity reservoir is a kind of special hydrocarbon reservoir in electric property and it is difficult to distinguish from water zone in well logging result. Low resistivity reservoir has become the important object of inereasing reserves and production in the middle-late stages of oilfield development, being regarded as a kind of important and particular hydrocarbon reservoir. It has an important significance to thoroughly analyze the genesis of low resistivity reservoir and to adopt the effective method to identify the low resistivity reservoir. In this paper, on the basis of the comprehensive analysis of bound water volume, lithology, porosity, clay mineral composition, water salinity and special conductive minerals, it is believed that the fine-grained content in sandstone is main influence factor of low resistivity reservoir in M Region. A new identification method of low resistivity reservoir is proposed, combined the cross plot of fine-grained sandstone content and resistivity with support vector machine, thraugh analyzing the influence of the fine-grained sandstone content on reservoir, physical prope1~y, pore development, bound water volume and clay mineral content. The cross plot of fine-grained sandstone content and resistivity is drawn up, which determines the threshold values of fine-grained sandstone content and resistivity in low resistivity reservoir and discriminates the sample point of known petroleum status again according to the support vector machine method. One low resistivity reservoir has been discriminated in M Region through the use of this method. The results show that the ability of identifying the low resistivity reservoir is obviously improved by the method, which displays a favorable application prospect.