Study On Surrounding Rock Stability And Optimized Layout Of Underground Energy Storage In Anhydrite

Establishing stable oil supply and strategic oil reserve system is the important guarantee of the healthy operation of national economy,International standard for oil reservation is 90 days,but at the present is only about 40 days in our country.Energy security situation is severe.Compared with the ground steel tank storage,other types of underground construction such as underground water seal storage,underground salt cavity and goaf covers less area,is safer and saving more expenses as well as environmentally friendly.Our country has three phase of the planning and construction of national petroleum reserve base and choose location in granite,gypsum as a storage medium previously.Yet if choosing anhydrite as a new storage medium,the surrounding rock stability will directly decide the success of underground energy storage.This paper is based on a deep mine goaf for underground petroleum reservation,uses engineering geological,indoor experiment and numerical simulation methods.The research includes:reservoir engineering geological features,rock and rock mass mechanics parameters of surrounding rock,different situations and permeating cavities stability and energy storage cavern swarm optimization layout.And results are as follows:(1)Both location advantage and the engineering geological conditions meet the conditions for building a research area.Fault distribution is obvious and there is no deep fracture.Ore body is thick,roof and floor of hydration shower belt formed a natural water barrier,both ore body engineering geological and hydrogeological conditions can meet requirements.(2)Typical rock mechanics parameters of anhydrite were obtained through laboratory test,rock mass mechanics parameters were estimated using Hoek-Brwon experience norms and geological strength index,the anhydrite reduction rules of surrounding rock and rock mass mechanics parameters were figured out from different spatial scales.All these results provide bases for the numerical simulation on the stability of surrounding rock for cavern group.(3)Numerical simulation model was established.The stability of surrounding rock of cavern group research under the condition of different initial stress state,different storage pressure state and different storage environment was carried out using the finite difference method.Surrounding rock stability safety of proposed energy storage mining area was evaluated by stress field,displacement field,plastic zone and unit safety coefficient method.(4)In order to satisfy the stability of surrounding rock and function quality of cavity,the effects that cavities pillar width,column height and interlayer thickness do on the unit safety coefficient of the surrounding rock and size as well as distribution of the plastic zone were studied by Orthogonal test.Thus,underground cavern swarm layout optimization scheme of HengTai anhydrite mine was determined.