The Risk Assessment And The Safety Analysis Of Underground Gas Cashing In Salt Rock

The salt rock has the properties of low permeability, creep behavior, damage self healing ability and other good characteristics, therefore it can provide a good storage cavern of natural gas with leakproofness and stability in spite of the dynamic stress. Casing as a migration channel concerns oil-gas production directly, which is an important hub to assure oil and gas wells operation normaly after drilling and well completion. The casing breakage is one of the important causes of gas storage failure. It is important to develop the research of the casing failure probability. So in order to explore the risk of casing, under the support of973subject--Risk assessment of catastrophe and regulation mechanism for soil and gas storage in the operation process, this paper adopts combination of experiments、theoretical analysis and numerical simulation. The content included in the article are presented as follows:1) The large-scale3-D rheological geomechanical model test of deep salt rock gas storages was carried out with the salt rock gas storage in Jintan, Jiangsu province as background. The influence of different risk factors (such as different gas injection velocity, high pressure, low pressure, loss of pressure) on the safety of casings were revealed effectively.2) Based on synthetically analysis of all kinds of researched results about casing loads and displacement in creep stratum. On the base of then presents casing safety analysis in creep stratum under uniform in-suit stresses are studied.3) During the operation storage, stochastic characters of geometrical size, load and material of the casing system are analyzed, which are applied in the safety analysis, failure probability calculation and sensitive factors analysis based on response surface method. As a calculation, casing thickness and gas press are important to the casing safety.4) The different conditions was simulated by the finite element method. And the calculation result is proved by the large-scale3-D geological model test. 5) The basic requirements of risk control of the salt cavern storage and casing during the operational period are proposed. The measures of risk control of cavern failure and casing failure.