Structural Design And Experimental Study Of Dissolvable Bridge Plug For Horizontal Well Fracturing

Shale gas exploitation is developing rapidly in China.Pumping bridge plug fracturing technology has been widely applied in shale gas production.As an important fractu ring tool,the bridge plugs must be removed from wellbore after fracturing,so as to ensure the smooth operation of oil and gas p roduction,The traditional method of milling is complicated and costly,and the method of material dissolving and removal is mon opolized by foreign technology T herefore,it is of great value to study a new technology of bridge plug removal.Inthis paper,the structure and removal method of bridge plug have been deeply studied,and some important research results have been obtained.A lightweight and high temperature resistant bridge plug has been researched and designed The bridge plug is mainly composed of sealing mechanism,anchorage locking mechanism and central tube assembly.The important components that affect the normal operation of the bridge plug are analyzed and determined,and the material characteristics,shape and size parameters are studied.The key design parameters that affect the sealing performance of bridge plug are obtained,which provides important basis for subsequent bridge plug structure optimization.The dovetail groove of the cone back ring is designed to ensure the normal operation of the anchor locking mechanism.Mechanical analysis and structural optimization of key components of bridge plug were carried out.By using the finite element method,the stress of rubber and slips were analyzed during working process of bridge plug.The general rule of contact stress distribution between casing and bridge plug was obtained,which provided an important basis for the structural optimization of each part.According to the key structural parameters of rubber and slips,the influence of various parameters on the contact performance of rubber and slips was studied.The optimum structural parameters of the rubber and slips were obtained by screening,the structure of the original design and the sealing performance of bridge plug were both improved.A new method to remove bridge plug quickly by electrochemical principle was put forward.The method used bridge plug,copper rod,electrolyte and external power supply to form an electrolytic cell system at the bottom of the well,and the bridge plug would dissolve quickly in the action of redox reaction,so as to achieve the purpose of removing the bridge plug.Compared with existing methods of removing bridge plugs,such as milling and material dissolving,electrolytic method not only guarantees high removal rate,but also does not require special materials and frequent lifting of pipe string.It has little damage to formation and low construction cost.The effect of electrolysis parameters on the electrolytic dissolution of bridge plug was studied.The effects of electrolyte formula?initial electrolyte temperature,electrode frontal area,electrode spacing,electrolysis voltage,impingement distance,and impingement method on electrolytic dissolution were revealed.The electrolytic parameters of high efficiency electrolytic dissolution were summarized,which provided experimental basis for the practical application of electrolytic dissolution of bridge plug.Built bridge plug electrolytic dissolution experimental platform,and completed the bridge plug electrolytic dissolution experiment.Finally,the feasibility of electrolysis dissolution is analyzed.