基于直接解调法的可控源地层元素测井联合解谱方法研究

Study on the Method of Combined Spectral Processing of Controlled Source Formation Element Logging Based on Direct Demodulation Method

可控源地层元素测井可以对地层中主要元素含量和矿物含量进行定量测量,获得地层中的碳、氧元素的含量和总有机碳含量(TOC)。矿物含量和TOC对复杂储层和页岩油气等非常规油气的测井评价具有重要意义,而碳、氧元素的定量测量可以在碳捕获、利用与封存中识别和量化近井区中的二氧化碳含量。提出一种基于直接解调法的可控源地层元素测井解谱方法,使用该方法对非弹性能谱和俘获能谱联合解谱获得元素的产额,使用氧化物闭合模型和架桥法获得地层中元素的含量。可控源地层元素测井仪在中国石油测井计量站的地层元素标准井群中进行了一系列的方法试验,结果表明,使用基于直接解调法的可控源地层元素测井联合解谱方法可以有效地提高能谱解析的精度。通过在吉林油田的现场试验验证,该方法计算的元素含量和矿物组分含量与区域地质特征相吻合,可准确反映地层岩性变化规律。

Controlled source formation element logging can quantitatively measure the content of main elements and minerals in the formation,obtain the content of carbon,oxygen and total organic carbon(TOC)in the formation.The mineral content and TOC are of great significance for log evaluation of unconventional oil and gas reservoirs such as complex reservoirs and shale oil and gas,while the quantitative measurement of carbon and oxygen elements can identify and quantify the carbon dioxide content in the near wellbore area in the carbon capture,utilization and storage(CCUS).We present a spectral processing method of element logging in controllable source formation element based on direct demodulation method in this paper.Using this method,the inelastic energy spectrum and capture energy spectrum are solved together to obtain the element yield.The oxide closure model and bridging method are used to obtain the element content in the formation.A large number of method tests have been carried out on the controllable source formation element logging tool in the formation element standard well group of the oil logging metering station.The results show that the precision of energy spectrum analysis can be effectively improved by using the combined spectral analysis method of the controllable source formation element logging based on the direct demodulation method. The field test in Jilin oilfield shows that the element content and mineral component content are consistent with the regional geological characteristics, which can accurately reflect the change law of formation lithology.