The Macro And Mesoscopic Characteristics Study On Damage Healing Of Salt Rock

As the basis of current and future economic development, oil and gas reserve strategies has been entered in the plans of the world’s major countries. Because of the well mechanical properties and low permeability characteristics as well as the mature technology, low cost of salt rock cavity construction, salt rock layer has been widely used in gas storage and other projects. Though salt rock can be an ideal gas storage space. Because of the complicated geological environment, it is unavoidable that deformation accidents may occur during construction and operation of salt cavity. As a result, the stability of the salt cavity research has a great significance to improve the utilization rate and prolong the service life of the salt cavity. Salt cavity stability is affected because of the complicated geological environment. However, due to the self-healing characteristics of salt rock, the recovery process of it has been carried out at the same time. So, the study of salt rock’s damage healing characteristics and regularity is extremely important to improve the stability of the salt cavity. Macro healing experiment and mesoscomic healing halite scanning for damage healing has been done to study damage healing in this paper. The characteristics of fracture healing in mesoscomic also has been analyzed, and damage rock salt’s healing regular under the pressure, water and temperature environment has been studied. Conclusions are carried out as follow:①Salt rock’s fracture healing structure can be distinguish with the following characteristics:1) there is fracture connection structure in the fracture; 2) there is not obvious sharp space and shadow boundary between the fracture connection structure; 3) the main composition of fracture connection structure is NaCl; 4) the connection between fracture connection structure and fracture surface acts as a concave shape.②The source of the rock salt structure fracture healing comes from two aspectses: 1) the accumulation of crystal separated from the brine; 2) the crystal growth unit’s growth on the fracture surface.③Because rich of crystal growth unit and driving energy of growth and so on,salt rock’s fracture healing is more likely to happen at the narrow area of the fracture, the fracture surface contains with impurities and the fracture tip.④With the increase of initial damage and confining compression degree or the prolongation of holding time of confining compression,the damage relative healing rate is on a rise when it’s under the confining compression situation. Greater initial damage can make more damage healing, however, it is at the cost of much more overall damage.⑤The process of saturated brine immersion and drying can created damage healing in salt rock; the improvement of drying temperature can relatively increase the healing degree.