LAWS STUDY ON DEEP SALT-BED CREEPING

Accurate analysis on the salt bed creeping is critical for the successful drilling engineering design and downhole troubles preventing and solving.By using over 20 core samples from Tarim Basin of Xinjiang, a series of creeping tests were conducted, i.e., singleaxle, tri-axle and step creeping tests, as well as circulating loading and unloading creeping tests, to investigate the salt bed creeping tendency. The results of the tests were analyzed, and an equation for simulating the creeping stress from transient creeping to stable creeping was presented, which well illustrate the irrelevancy of the process from transient creeping to stable creeping with time.It was concluded that the creeping stress ratio does not depend on the stress path, while it is only a function of the stress state.A constitutive equation describing the creeping deformation was also proposed, providing a scientific basis for analyzing the salt bed creeping tendency and calculating the creeping pressure.