Impact of Logging Speed on Sedimentary Rock Identification Based on Long and Short Density Log

Abstract

Logging speed has an influence on data quality of logging result because each rock has its own characteristics. Sedimentary rocks with low mechanical properties have specific geophysical characteristics, therefore in logging activity, it is necessary to determine the optimum speed to obtain the best data quality. This research aims to evaluate optimum logging speed for sedimentary rocks to determine the logging speed that is suitable for the characteristics of sedimentary rocks. The research was conducted by logging one of the drilling holes using GDDC probe. The logging speeds used in the measurement were 3, 4 and 5 m/min. For each measurement, data values of long spaced density (LSD) and short spaced density (SSD) were obtained. The data was evaluated by statistical analysis using Friedman test. The result shows that LSD data result at logging speed of 3 m/min is different from the data at the speed of 4 and 5 m/min; while the SSD data result at logging speed of 3, 4, and 5 m/min are different from each other. A logging speed of 4-5 m/min is recommended for logging activity on clastic sedimentary rocks that have low mechanical properties.

Empirical Analysis of Density Value Based on Laboratory Test and Geophysical Log on Sedimentary Rock

“…The logging was carried out at a speed of 5 m/min after boreholes had been cleaned from mud from drilling activity. The logging speed of 5 m/min is the optimum speed to produce stable data quality on the sedimentary rock [18]. Rock density was measured using GDDC (Gamma Dual Density and Caliper) type probe at both short-spaced density (SSD) and long-spaced density (LSD).…”