Nuclear Techniques ›› 2018, Vol. 41 ›› Issue (10): 100502-100502.doi: 10.11889/j.0253-3219.2018.hjs.41.100502


Calculation of borehole diameter and standoff using logging while drilling density logging

CHEN Xianghong1,2, YU Huawei1,2, ZHOU Yue1,2, ZHANG Feng1,2, WANG Zhigang3   

  1. 1 China University of Petroleum(Huadong), Qingdao 266580, China;
    2 Laboratory for Marine Mineral Resources, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266071, China;
    3 Changqing Oil Field Branch Sixth Gas Production Plant, Xi'an 710000, China
  • Received:2018-04-26 Revised:2018-05-26 Online:2018-10-10 Published:2018-10-16
  • Supported by:
    Supported by National Natural Science Foundation of China (No.41674129), the National Key Research and Development Program of China (No.2016YFC0302800), Fundamental Research Funds for the Central Universities (No.14CX02182A, No.16CX02039A), Teaching Reform Project for China University of Petroleum (No.SY-A201405), National Science and Technology Major Project (No.2017ZX05009001)

Abstract: [Background] Borehole diameter (bore diameter) and standoff are important parameters that affect the precision of the logging while drilling (LWD) tool.[Purpose] This study aims at the method of accurately calculating the instrument-to-hole standoff and borehole diameter by using the azimuthal density LWD.[Methods] A Monte Carlo simulation was used to establish the instrument calculation model, and the simulation results and experimental data were benchmarked. Then, the effect of 0~5 cm standoff on the response of the detector was studied by changing the standoff size, formation density and mud density. Finally, the standoff size can be calculated by measuring the detector's density, formation density, and mud density whilst the caliper can determined by using the geometric relationship.[Results] The density measured by the detector is affected by the standoff, mud density, and the density of the formation. When the difference between the formation density and the mud density (difference in the medium density) are constant, the difference between the formation density and the far density (measured density difference) are proportional to the value of standoff. The calculation accuracy of borehole diameter reaches 0.1 cm.[Conclusion] This study provides a theoretical foundation for calculating standoff and borehole diameter in practical projects in the future.

Key words: LWD density loggings, Standoff, Monte Carlo simulation, Borehole diameter

CLC Number: 

  • TL99