钻定向井水平井已成为近些年钻井行业的热点.钻水平井过程中,地质导向起着关键作用,井眼轨迹的动态监测是其中的一个重要方面,包括沿钻进方向钻头距上下界面距离及距界面的垂直距离等,从而使井眼轨迹尽量保持在目的层中,最大限度的提高油气采收率.本文基于方位伽马测井的测量原理并结合几何特征,推导了一种随钻方位伽马测井的快速正演方法,该方法使正演计算中的复杂性大大降低,克服了利用蒙特卡罗方法正演模拟的困难.同时,本文利用方位伽马正演模拟曲线,对钻进过程中沿钻进方向上钻头到层界面距离及钻头距界面的垂直距离进行了反演计算.通过正演及反演结果对比,证明该方法在地质导向中应用的可行性. Drilling Directional Horizontal Wells has become a hot spot in the drilling industry in recent years. Geological steering plays a key role in horizontal well drilling. Dynamic monitoring of well trajectory is one of the important aspects, including drilling along the drilling direction from upper and lower interfaces Distance and vertical distance from the interface, so that the wellbore trajectory as far as possible to maintain the target layer, maximize the recovery of oil and gas.In this paper, based on the principle of azimuth logging azimuth and geometric features, derived a This method can greatly reduce the complexity in forward calculation and overcome the difficulty of forward modeling by Monte Carlo method.At the same time, this paper makes use of the azimuth gamma forward modeling curve, The distance between the drill-layer interface and the vertical distance of the drill bit from the interface along the drilling direction during drilling is calculated and the feasibility of the method is proved by the comparison of the forward and inversion results.