Dynamic subsidence prediction of ground surface above salt cavern gas storage considering the creep of rock salt

Abstract

A new model is proposed to predict the dynamic subsidence of ground surface above salt cavern gas storage during the leaching and storage, which takes into account the creep of rock salt. In the model, the extended form of Gaussian curve is adopted to figure out the shape of subsidence areas. The corresponding theoretical formulas are derived. In addition, parameters are studied to investigate the surface subsidence as a function of the salt ejection rate, internal pressure, buried depth, diameter, height, running time, etc. Through an example, the subsidence of the salt cavern gas storage located at Jiangsu of China obtained by the new model was compared with those by Peter A F formula, Schober & Sroka formula and FLAC 3D through simulation. The results showed the proposed model is precise and correct, and can meet the actual engineering demands. The surface subsidence is equidirectional with the increase of salt ejection rate, depth, diameter, height, and running time, but reverse to the increase of internal pressure. The depth, diameter, running time and internal pressure have great effects on the subsidence, whereas the salt ejection rate and height have little influences on it.salt cavern gas storage, dynamic subsidence, creep of rock salt, extended form of Gaussian curve, calculation model Citation:Wang T T, Yan X Z, Yang X J, et al. Dynamic subsidence prediction of ground surface above salt cavern gas storage considering the creep of rock salt.

Time-dependent subsidence prediction model and influence factor analysis for underground gas storages in bedded salt formations

“…As the storage cavern is located deeper, the influence radius of the subsidence trough increases. Different from the research by Wang et al (2010), the maximum subsidence at the ground center increases first and then decreases as the cavern is constructed deeper. In this case, the inflection point is at a depth of approximately 1200 m. The reasons include two aspects:…”

“…The volume reduction of the storage cavern is the basic reason of the surface subsidence Kong et al, 2012;Wang et al, 2010). Assuming that the surface subsidence volume is proportional to the volume reduction of the salt cavern, the time-dependent surface subsidence at any location can be expressed as Eq.…”

“…In order to verify the proposed prediction model, the numerical software FLAC3D 3.0 (Swift and Reddish, 2005;Wang et al, 2010;Li et al, 2011Li et al, , 2012Kong et al, 2012;Yang et al, 2013) was adopted. The FLAC3D can be used to simulate the behavior of materials that exhibit creep -i.e., time-dependent material behavior.…”

“…This model belongs to the semi-analytical and semi-finite element prediction models, and requires computation of the volume reduction in advance by numerical simulation. Wang et al (2010) proposed a model to predict the dynamic subsidence above salt cavern gas storage during the leaching and storage. They considered the creep of rock salt but they did not consider the impurity of the salt, and they assumed the cavern to be a cylinder, which is far different from the real shape of underground gas storage caverns.…”

Stability analysis of the pillars between bedded salt cavern gas storages by cusp catastrophe model

“…The security and disaster prevention of salt cavern gas storages are hot topics [30] in engineering research for the exigent demands of energy security in China. In 2009, the Ministry of Science and Technology of China launched the National Basic Research Program of China "the Disaster Mechanism and Protection of Energy Reserves in Underground Storages ("973" Program)" to promote the safety researches of underground gas storage at a national level.…”