近钻头伽马成像仪测量结果环境校正方法研究

Research on Environmental Correction Method of Measurement Results from Near-Bit Gamma Imagers

李洪强 王瑞和

LI Hongqiang WANG Ruihe

中国石油大学（华东）石油工程学院，山东青岛 266580 中石化胜利石油工程有限公司钻井工艺研究院，山东东营 257000

School of Petroleum Engineering, China University of Petroleum (East China), Qingdao, Shandong, 266580, China Drilling Technology Research Institute, Sinopec Shengli Oilfield Service Corporation, Dongying, Shandong, 257000, China

实际工况下近钻头伽马成像仪在井筒中难以保持绝对居中，需要根据偏心程度对不同方向上的伽马扇区原始测量数值进行环境校正。依据伽马成像测量原理以及近钻头伽马成像仪的结构特点，分析了不同工况下近钻头伽马成像仪偏心程度对测量结果的影响，建立了近钻头伽马成像仪偏心情况下钻井液衰减、钾基钻井液补偿等主要因素的修正图版和校正方法。试验结果表明，偏心条件下，由于井筒和近钻头伽马成像仪之间环空内钻井液的影响，根据原始伽马成像图谱计算出的地层倾角存在较大误差。采用建立的校正方法对偏心情况下的近钻头伽马成像图谱进行测量环境校正后，利用其计算出的地层倾角与地层真实倾角基本一致。研究结果表明，采用建立的测量环境校正方法对近钻头伽马成像仪偏心情况下获得的伽马成像图谱进行环境校正后，可以真实反映地层情况，计算出的地层倾角更准确。

It is difficult to maintain absolute centering in the wellbore under the actual working conditions of near-bit gamma imagers. For that reason, the environment associated with the original measurement values of gamma sectors in different directions should be corrected according to the eccentricity. Using the principle of gamma imaging and the structural characteristics of the near-bit gamma imager, the influences of the imager eccentricity on the measurement results under different working conditions were studied. The results were used to develop correction charts and methods for the main factors such as attenuation in drilling fluids and compensation in potassium-based drilling fluids when the near-bit gamma imagers were under eccentric condition. The results revealed that the formation dip calculated by the original gamma imaging analysis had a large error due to the influence of drilling fluid in the annulus between the wellbore and the instrument under such condition. In contrast, after environmental correction of near-bit gamma imaging under eccentric condition, the formation dip calculated by the correction method was essentially consistent with the real one. The research results showed that the gamma spectra obtained using near-bit gamma imager under eccentric condition could reflect the real formation after environmental correction, and could calculate the formation dip more accurately.

国家科技重大专项项目“复杂断块油田提高采收率技术”（编号：2016ZX05011-002）资助

https://doi.org/10.11911/syztjs.2021024