Experimental Study on the Consolidation Strength of Old Well Plugged Back Interface in Salt Cavern Gas Storage
The existing cement plug consolidation strength tests do not take into account the influences of high temperature and high pressure,and are mostly conducted on the shear consolidation strength of cement plugs at normal temperature and normal pressure.Therefore,an in-situ testing device for the comprehensive consolidation strength of old well plugged back cement plug in salt cavern gas storage was designed for cement plug consolidation strength tests under different interface,cement plug length/diameter and cement slurry system conditions,at the simulated temperature and pressure(80℃and 15 MPa),to clarify the influences of different factors on the con-solidation strength.The experimental results show that the consolidation strength of the cement plug-rock/casing in-terface is greatly affected by the cement slurry system;the interfacial consolidation strength under the salt layer ce-ment slurry system is greater than that under the caprock cement slurry system;the cement plug-rock interfacial consolidation strength is slightly greater than the cement plug-casing interfacial consolidation strength;the tensile consolidation strength of the cement plug-rock/casing interface is lower than the shear consolidation strength,and the ratio of them is 0.41-0.45.The research results provide important theoretical support for the prediction of sealing failure at old well plugged back interface in salt cavern gas storages.
salt cavern gas storageinterfacial consolidation strengthcement slurry systemcement plug di-ametercement plug length