Thefracture Influence Analysis On Salt Rock Cavern Considering Creep-damage Characteristics

Salt rock is very different from general rocks, since it has engineering fetures such as less fracture, low porosity, low permeability, strong creep and damage healing; salt rock layer is internationally recognized as the ideal deposit for constructing underground storage of oil and natural gas. In foreign countries, several accidents of fire, explosion, and collapse have occurred in natural gas reservoir, which caused a great deal of losses, many of them are caused by the creep damage of salt rock. However, the research of underground salt reservoir was started relatively late in China, and the study of salt rock with fracture was rarely seen in references. According to the character that most salt rock in China has layered distribution, and most of them have the character of interlayer. The influence of interlayer fracture to salt rock storage cavern and to the creep damage characteristics of the salt rock was studied in this paper.First, this paper discusses the physical and mechanical properties, rheological damage properties of salt rock and the creep damage model.Secondly, using secondary development tools UPFs provided by ANSYS software,and creep damage healing model- userc_d model of salt rock by Professor Guijun Wang,user subroutine which can be called by ANSYS directly was written. The test sample numerical model used in salt rock triaxial compression creep experiment was established in the ANSYS environment, and the correctness of the model was validated.In the end, reservoir model with fracture and no fracture was respectively established by ANSYS, and the developed user subroutine was used for numerical simulation analysis of the reservoir model. Through comparison and analysis about surrounding rock of reservoir model with fracture and no fracture in such aspects as deformation and creep damage, draw the creep damage characteristic influence law to salt rock storage cavern that fracture gave. Also the influence law of natural gas on creep damage characteristics of reservoir was analyzed.By means of the secondary development function of finite element software ANSYS,the influence of fracture on creep damage and deformation of salt rock storage cavern was studied. This is an innovation point of the paper...