지하물성의 정보화를 위한 물리검층 품질관리 연구
|서명||지하물성의 정보화를 위한 물리검층 품질관리 연구|
|초록||Despite the great availability of geophysical data obtained from boreholes, the interpretation is subject to significant uncertainties. More accurate data with less statistical uncertainties should require an employment of more quantitative techniques in log acquisition and interpretation technique. The long-term objective of this project is the development of techniques in both quality control of log measurement and the quantitative interpretation. In the first year, the goals of the project will include establishing the procedure of log acquisition using various tests, analysing the effect of logging velocity change on the logging data, examining the repeatability and reproducibility, analyzing of filtering effect on the log measurements, and finally the zonation and the correlation of single-and inter-well log data. For the establishment of logging procedure, we have tested the multiple factors affecting the accuracy in depth. The factors are divided into two parts: human and mechanical. These factors include the zero setting of depth, the calculation of offset for the sonde, the stretching effect of cable, and measuring wheel accuracy. We conclude that the error in depth setting results primarily from human factor, and also in part from the stretching of cable. The statistical fluctuation of log measurements increases according to increasing the logging speed for the zone of lower natural gamma. Thus, the problem related with logging speed is a trifling matter in case of the application of resources exploration, the logging speed should run more slowly to reduce the statistical fluctuation of natural gamma with lithologic correlation in mind. The repeatability and reproducibility of logging measurements are tested. The results of repeatability test for the natural gamma sonde are qualitatively acceptable in the reproducibility test, the errors occurs in logging data between two operators and successive trials. We conclude that the errors result from the incorrect depth setting. The digital filtering for the log data are compared with power spectrum. The time domain filtering of Savitzky and Glaoy is superior to the typical moving averaging method. The vertical resolution in frequency filtering can be improved while rejecting the noise by the adjustment of filter's frequency. The calibration method of various sonde are discussed and performed. The caliper calibration should be run before and after the survey to get rid of the problem with the drifts. The calibration for the natural gamma and tertiary calibration of density sonde was performed first in Korea and consequently the conversion CPS (Count Per Sec) unit to real unit (i.e., API unit or g/cc) was carried out with success. Geologic zonation using the normalized difference method was studied for quantitative interpretation. The correlation of slowness with single point resistance is better for the fractured rock. The logging data for petrologic zonation was classified by a statistical technique and compared with coring columns. This process yields even more sophisticated results. The cross correlation method as a signal processing technique was employed for analysing a possible correlation between inter-well natural gamma measurements|
|페이지||vi, 65 p.|
|키워드||지하, 지하물성, 정보화, 물리검층, 품질관리|
이상규. (1998). 지하물성의 정보화를 위한 물리검층 품질관리 연구. 韓國資源硏究所.