深层盐膏岩蠕动规律研究

LAWS STUDY ON DEEP SALT-BED CREEPING

盐层蠕动变形规律的分析是成功地进行盐膏层钻井设计和井下事故预防和治理的关键。用新疆塔里木盆地兰尕等构造的 2 0多块岩心对盐膏层蠕动规律开展单轴、三轴、阶梯蠕变试验和循环卸载、加载蠕变试验等 ,并对蠕变试验结果进行了分析 ,提出了模拟蠕变应变从瞬态蠕变到稳态蠕变的方程式 ,较好地拟合了从瞬态到稳态对时间的不依赖性 ;得出了蠕变应变率不依赖于应力路径 ,仅是应力状态的函数 ,同时还得出了描述变形的本构方程 ,为分析盐膏层蠕动规律和计算蠕动压力提供了科学依据。

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., single axle, 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.