随钻自然伽马地层边界模型分析　

Modeling and analysis of formation boundaries based on LWD natural gamma

向长生 王智锋 亢武臣

XIANG Changsheng WANG Zhifeng KANG Wuchen

中国石油大学华东石油工程学院，山东青岛　266580 胜利石油管理局钻井工艺研究院，山东东营　257017

School of Petroleum Engineering, China University of Petroleum, Qingdao 266580, China Drilling Technology Research Institute of Shengli Petroleum Administration, Dongying 257017, China

给出了一种基于无限均匀水平地层模型中根据自然伽马通量计算探测点距离地层边界的解析求解法。该方法采用球坐标建立数学模型，假设探测点为理想点，地层为水平无限均匀模型；解析形式十分简单，便于编程计算分析提高效率，并且可以单独开发成计算模块供其他程序调用，对于地质导向等技术和后期分析随钻测井数据、确定地层边界具有一定参考价值。该模型还有较大的完善空间，比如方位性、薄地层的识别等，还有待进一步分析研究以便尽快在实践中得以应用。

An analytic solution of calculating the distance between measurement point and formation boundary using natural gamma flux was given in this paper based on infinite uniform horizontal strata model. Building mathematical model with the spherical coordinates, it is assumed that the probe points are ideal points, and the stratum is similar to horizontal infinite uniform model. The analytical solution form is very simple and easily programming analysis to improve efficiency, and can be developed to separate calculation module which could called for other programs. It also has certain reference value for analyzing techniques such as geologic steering, LWD logging data post-analysis and stratigraphic boundary determination. The model still has space to improve, such as orientation and thin strata identification; besides, further analysis and investigation are also need to make sure the technique being applied in practice as soon as possible.