文昌13-1油田低阻油层测井岩性识别方法研究

Lithological Identification for Low-resistivity Reservoirs by Well Logging Method in Wenchang13-1 Oilfield

文昌13-1油田低阻层段由于测井曲线幅度起伏较小,垂向上岩性变化频繁,导致测井岩性识别难度大。针对油田实际地质特征,充分考虑油田低阻层段与高阻层段之间的差异,筛选了自然伽马、中子孔隙度、声波时差、深感应电阻率4条测井曲线,并对这4条测井曲线逐一进行了标准化处理。同时,采用测井曲线交会图版法,统计了不同岩性之间的测井曲线特征,在此基础上,分别制定了低阻层段与高阻层段岩性识别标准,并编制了识别程序,共识别出砂岩、砂质泥岩、泥质砂岩、泥岩和钙质砂岩5种岩性。从识别结果来看,该方法适合文昌13-1油田,识别结果与取心岩性符合率较高,识别结果可用,且大大减轻了人工识别工作量。

The identification of the lithology for the low-resistivity reservoirs was difficult,due to less changes of well logging curves and frequent and vertical changes of lithology.In allusion to the actual geological characters of oilfieds,the variations between the low-resistivity and high-resistivity reservoirs was fully taken into consideration,four kinds of well logging curves,including natural gamma ray,neutron,acoustic transit time and deep induction resistivity logging were chosen and the standardization processing was carried out for those four curves,and the cross plot chart method for logging curves method was used for the statistics of well logging curves between different lithological properties.On the basis stated,identification standard was established for low-resistivity and high-resistivity reservoirs respectively and identification programs was developed to identity five kinds of lithologicl properties,including sandstone,sandy mudstone,argillaceous sandstone,mudstone and calcareous sandstone.Seeing from the results of identification,it is found out that this method is suitable for Wenchang 13-1 Oilfield and the identification results are consistent with that of cores,therefore the identification results are reliable,by which work load of manual identification is reduced.