According to the requirement of theWest-East GasTransmission Pipeline Project in China, 6 existing salt caverns in Jintan Salt Mine, Jiangsu province, were selected as natural gas storages. In the paper, the feasibility of this use is evaluated through the geological investigation of salt rock occurrence, the mechanical experiments and numerical simulating.A positive conclusion is given.
Salt rocks are generally recognized to be the ideal geologic host rocks for storage of gas and crude oil and are also being considered to be used in the disposal of radioactive waste. So far, numerous foreign researchers have already carried out many studies [1−11] on the strength and deformation characteristics of salt rocks in laboratory and field and established constitutive models of relationships among the damage, deformation and permeability of salt rocks. However, the sedimentary characteristics of salt rocks in China are much different from those in Europe and North America. So those preexisting models can not be applied directly to the construction of salt caverns in China. In this paper, the feasibility study of the Jintan gas storage project was in detail introduced. The project is to use some existing solution-mined caverns in Jintan Salt Mine as gas storages.
According to the borehole data, the salt rock of Jintan Salt Mine is relatively steady along the horizontal direction and the vertical direction. The salt rock deposit occupies an area of 60.5 km2: the long axis 12 km and the short axis 5.6 km, with the thickness varying from 67.85m to 230.95 m. The central part of the salt rock deposit, with a range of 180–230 m, is thicker than the other parts. The depth of the top surface is 850m~1100 m. From bottom to top there are three major salt layers: I, II, and III. The average thickness of layer I is 58m. Layer II is uniformly distributed, with the thickness varying between 50mand 80 m, averaging 64 m.This layer has caverns to be capable of being used as gas storages. Layer III is only 30m~50m thick.
To satisfy the requirement of structure and volume of gas storage, about 15 salt caverns for gas storage were selected from 30 old solution-mined caverns. Among these selected caverns, 6 caverns, namely caverns West-1, West-2, East-1, East-2, Gang-1and Gang-2, were chosen as research objects for evaluating the usability of these caverns as gas storage. The in-situ sonar measures of the cavern boundary were carried out. As an example, the sonar measure result of cavern East-1 is shown in Figure 1. Caverns West-1and West2 are in Xizhiqiao well field of Jintan Salt Mine and about 104.43mapart.
To investigate the mechanical properties of salt rocks, a series of laboratory test including uniaxial compression, triaxial compression, and creep experiment by the XTR01 Electricfluid Serving Compression Machine were carried out.