CAJ | 학술논문

蒙特卡罗模拟是放射性测井一种重要的数值模拟方法，利用通用程序MCNP可方便地建立各种地层模型，为放射性测井研究提供了简便有效的方法。借助于蒙特卡罗方法建立随钻条件下地层模型，正演模拟随钻方位伽马成像特征。结果表明，随钻方位伽马成像图呈现正弦线特征，利用成像图可准确反演井眼相对倾角和放射性地层厚度；井眼相对倾角越大，放射性地层厚度越厚，成像图的正弦线高度值及在井轴方向上的展布高度值越大；井眼尺寸对利用成像图求取井眼相对倾角没有影响，但对计算放射性地层厚度有影响，仪器偏心对利用成像图求取井眼相对倾角和放射性地层厚度都有较大影响，若伽马计数满足测井计数统计性，可忽略井眼流体对成像图的影响。
몽특잡라모의시방사성측정일충중요적수치모의방법，이용통용정서MCNP가방편지건립각충지층모형，위방사성측정연구제공료간편유효적방법。차조우몽특잡라방법건립수찬조건하지층모형，정연모의수찬방위가마성상특정。결과표명，수찬방위가마성상도정현정현선특정，이용성상도가준학반연정안상대경각화방사성지층후도；정안상대경각월대，방사성지층후도월후，성상도적정현선고도치급재정축방향상적전포고도치월대；정안척촌대이용성상도구취정안상대경각몰유영향，단대계산방사성지층후도유영향，의기편심대이용성상도구취정안상대경각화방사성지층후도도유교대영향，약가마계수만족측정계수통계성，가홀략정안류체대성상도적영향。
Monte Carlo simulation is one of the most important numerical simulation methods in nuclear logging. Formation models can be conveniently built with MCNP code, which provides a simple and effective approach for fundamental study of nuclear logging. Monte Carlo method is employed to set up formation models under logging while drilling condition, and the characteristic of azimuthal gamma imaging is simulated. The results present that the azimuthal gamma imaging shows a sinusoidal curve features. The imaging can be used to accurately calculate the relative dip angle of borehole and thickness of radioactive formation. The larger relative dip angle of borehole and the thicker radioactive formation lead to the larger height of the sinusoidal curve in the imaging. The borehole size has no affect for the calculation of the relative dip angle, but largely affects the determination of formation thickness. The standoff of logging tool has great influence for the calculation of the relative dip angle and formation thickness. If the gamma ray counts meet the demand of counting statistics in nuclear logging, the effect of borehole fluid on the imaging can be ignored.