The Casing Cement Sheath Mechanical Properties Studies

The casing pipe and cement rings are the key part of the well cementing,and they also have an important effect on the wells'service life.The main function of cement ring is to effectively seal the annular space outside of the casing pipe, sequentially prevent occurrence of fluid channeling in the process of drilling, operation and production.Meanwhile, it provides effective protection and support for the internal casing,as well as alleviating and reducing the surrounding rock's squeezing action to the casing pipe,then improving the structure of three-dimensional loads.In addition, it could protect the casing from corrode by underground fluid, sequentially prolong the well's service life,and ensure the well's normal production.The main research contents of this paper include:1.Clearly understand the current strength calculation method for casing pipes and cement rings,and the types and their respective characteristics of casing pipe, as well as the main parameters of cement ring and the mud's condensate and harden process and combining mechanism through investigation and research.2.On the basis of elastic-plastic mechanics theory, obtain the multi-layer casing and cement ring between analytical solution of stress and strain, and get the casing and cement ring in radial and surround to the stress-strain relationship through the theoretical analysis of the combination of casing and cement ring the mechanical model. Meanwhile, analyzed the casing and cement ring the bond-slip relationship between, got the expression about bond force.3.On the basis of the theoretical analysis, combined with computer numerical calculation method, and utilized numerical analysis software ANSYS to analyse casing and cement ring 3-d model, get the stress and strain cloud graph of the casing and cement ring under the action of internal and exterior pressure, and obtained the corresponding curves.4.Briefly considered the action of shallow casing cement ring under the horizontal earthquake forces, and analyzed the seismic effects on the casing and cement ring, and consider the cement ring seal will not damage.Through studies on the mechanical properties between the casing pipe and the cement ring, we had a certain understanding about casing pipe and the cement ring, and obtianed corresponding results. It would provide a certain reference for the follow-up research work.