Study On The Influence Of Cementing Quality Of Shale Gas Horizontal Wells On Casing Damage In Weiyuan Area, Changning

In the Changning-Weiyuan national shale gas demonstration area,southwestern Sichuan Basin,due to casing failures of some wells,some problems occur,like the bridge plug not being smoothly put into the hole and successfully drilled during the fracturing operation.What's more,fracturing operations have been given up in some parts of the well.All of these affect the increase of gas production.Getting comparison and analysis of the invalid of shale gas wells at Chinese and abroad,we study on the influence of cementing quality on casing failure of horizontal shale gas well.Taking the well of WH1 as samples,one believes that the poor quality of cementing is important factor on the casing failure by analyzing the basic situation of the casing failure in the process of fracturing.By finite element software-ABAQUS,combined with the actual site model parameters,the numerical calculation is performed for poor cementing quality of three forms,namely cement channel,eccentric casing and borehole diameter variation.It obtains the influence of the cement channel,the eccentric casing Micro annulus and borehole diameter variation on casing stress.The results show that:in the fracturing process,cement channel and eccentric casing will greatly increase casing stress,even to the casing yield value,while borehole diameter variation has few effect on casing stress.Above results have some significance for the future of shale gas production.