含岩屑砂岩储层“甜点”测井评价技术难点与对策

Difficulties and strategy of logging evaluation on“sweet spots”of lithic sandstone reservoirs

含岩屑砂岩矿物成分复杂多样,多种矿物成分改变了测井曲线信号响应规律,使得流体识别困难。为此,作为宏微尺度的桥梁,从两方面对此类砂岩的测井评价技术进行了研究:一是流体定性判别研究,建立岩石薄片刻度测井曲线方法,研究“甜点”的测井响应特征,形成“甜点”测井敏感信号的提取与放大技术;二是储层定量评价研究,探索多矿物储层的孔隙度混合骨架值的确定,建立基于电阻率的变m值饱和度计算方法,以期实现复杂矿物储层饱和度的精确计算和含岩屑砂岩储层的精确评价。将上述研究结果应用于大牛地气田上古生界地层,结果表明,计算的孔隙度、饱和度与岩心实验分析结果一致,解释结果经试油验证准确可靠,为此类储层的系统测井评价提供了分析依据。

Lithic sandstones exhibit complex and diverse mineral composition.Various minerals alter the signal response law of logging curves,resulting in difficulty with identifying fluids.Well logging methods for lithic sandstone are investigated from two perspectives as a bridge between macrovisual and microvisual techniques.First,a qualitative identification of fluid is performed by establishing a method for logging the curve of rock slices to study the logging response characteristics of“sweet spots,”thereby forming the technology to extract and magnify discrete“sweet spot”signals.Second,a quantitative evaluation of the reservoir is performed.The aggregate skeleton value of porosity in multi-mineral reservoirs is determined and the saturation calculation methods of the variable m are established based on resistivity.This allows the achievement of an accurate calculation of saturation in complex mineral reservoirs and an accurate evaluation of lithic sandstone reservoirs.Upon application of the above methods to the Upper Paleozoic Daniudi Gas Field,the calculated porosity and saturation were consistent with results from the core experiment analysis.Oil testing proved that the interpreted results were accurate and reliable,and can thereby provide a method and data support for logging evaluation of lithic sandstone reservoirs.