During drilling operations in cold regions, the frozen soil obtains strong creep characteristics, which will result in wellbore shrinkage. An unreasonable drilling fluid density may cause engineering accidents, such as blocking and stuck drills. To solve this problem, a drilling fluid density calculation model based on the power law model of frozen soil creep was established in this paper for controlling the wellbore shrinkage in frozen soil. The factors affecting the wellbore shrinkage rate in frozen soil were analyzed. A map of the wellbore shrinkage and drilling fluid density was also established. The results show that the wellbore shrinkage rate is affected not only by the physical properties of the frozen soil but also factors such as the temperature, formation depth, drilling fluid density, wellbore size, and well opening time. The density of the drilling fluid required for safe drilling in frozen soil increases as the formation depth increases, and the magnitude gradually decreases. As the temperature decreases, the drilling fluid density at the same depth gradually decreases, and the magnitude also gradually decreases. The results provide an important basis for determining the drilling fluid density and the selection of drilling methods in cold regions.
|Name||56th U.S. Rock Mechanics/Geomechanics Symposium|
|Conference||56th U.S. Rock Mechanics/Geomechanics Symposium|
|Period||26/06/22 → 29/06/22|