Study On The Mechanism Of Casing Damage In Sa'nan Development Area

The causes of casing damage can be divided into 2 categories: the geological factors and engineering-technical factors. The former include geo-stress, layer slippage, clay creep, the strata plastic creep, sanding, fault activities, etc. The latter include high-pressure injection, unbalanced injection and production, well consolidation quality, perforation and repeated operation, acidification, etc. However, the existing study on these factor are only qualitatively.Based on the fluid-solid coupling theory, the flow-displacement mathematical model is set up by analyzing the coupling between the petroleum reservoir flow and geo-stress. This model is used in the study on the borehole pressure variation, the external load induced imposed on the casing, and the influence on the casing damage in the process of pressure and flow releasing of the injection wells. At the same time, the mechanism of strata-displacement-induced casing damage is studied due to the production pressure variation in the injection-production process. This helps determine the pressure release speed and the production pressure limits in the casing protection.The following studies are carried out based on the existing ones: (1) the effect of different perforation styles on the casing strength, (2) the influence of pore pressure on the casing damage, and (3) the continuum media model of flow in the petroleum reservoir and strata displacement. The flow-fluid coupling theory is used in assessing the effect of pore pressure variation on the casing displacement.