直接确定地层有机碳含量测井方法的数值模拟  

Numerical Simulation on Logging Method of Direct Determination of Total Organic Carbon Content in Formation

作　　者：袁超[1] 周灿灿[1] 薄亚杰 张锋[3] 李霞[1] 程相志[1] 

机构地区：[1]中国石油勘探开发研究院测井与遥感技术研究所,北京100083 [2]中国石油测井有限公司技术中心,陕西西安710077 [3]中国石油大学(华东)地球科学与技术学院,山东青岛266580

出　　处：《原子能科学技术》2015年第8期1497-1503,共7页Atomic Energy Science and Technology

基　　金：国家重大油气专项资助项目(2011ZX0520-008);国家自然科学基金资助项目(41374125)

摘　　要：非常规资源逐渐成为我国油气勘探的重要领域,其"源储一体"的特性使得对源岩特别是有机碳含量的连续定量评价成为关键。传统测井评价方法均是基于测井资料的间接评价,受多种因素影响,计算结果有一定的不确定性。本文利用快中子与地层元素原子核发生反应产生的非弹性散射伽马能谱和俘获伽马能谱,通过谱分析技术获取地层元素含量,根据与无机碳相关的钙、镁等元素含量确定无机碳含量,从总碳含量中扣除无机碳含量可直接提供高精度的有机碳含量信息。借助于蒙特卡罗数值模拟方法,建立了6种四川盆地龙马溪组和筇竹寺组页岩地层模型,模拟不同地层条件下的混合伽马能谱,并利用模拟元素的标准伽马能谱对模拟能谱进行谱解析。模拟结果表明,本文的方法可直接提供高精度的有机碳含量,有机碳含量大于2%时,其计算值相对误差小于6%。Unconventional resources gradually become the important domain of oil and gas exploration in China, in which the evaluation of source rock, especially the total organic carbon content （Toc）, is critical due to the ＂source and reservoir in one body＂. Conventional evaluation methods of Toc based on logging data are all indirect ones, and calculated results involve some uncertainties as they are affected by various influential factors. In this paper, inelastic gamma spectra and capture gamma spectra were recor- ded with the gamma ray detector, and elemental contents in formation were derived with spectral analysis technique. After that, the total inorganic carbon content （TIC）, which is calculated with the Tic-related elemental contents, was deducted from total carbon content （Tc） to directly determine Toc. According to the characteristics of shale in Longmaxi and Qiongzhusi formation of Siehuan basin, Monte Carlo method was em- ployed to build 6 formation models, gamma spectra under different formation conditions were simulated, and then the simulated gamma spectra were analyzed with elemental standard gamma spectra. The simulation results demonstrate that the method mentioned in this paper can directly provide high-accuracy results of Toc, and the relative error of calculated value is less than 6% when Toc is more than 2 %.

关 键 词：有机碳含量直接确定 脉冲中子测井 伽马能谱 数值模拟 

分 类 号：P631.817[天文地球—地质矿产勘探]