Research On Soluble Spherical Seat Based On Oil Fracturing

During recent years,horizontal well staged fracturing technology has been extensively applied to oil exploitation,which promoted efficient production of oil.The downhole fracturing tool plays vital role during fracturing and it influences oil exploitation efficiency.Fracturing ball seat plays important function since it is one of the downhole fracturing tools.However,the traditional fracturing ball seat is mostly made of drillable nodular cast iron;that is to say,drilling removal is required after fracturing with long time consumption,high cost and complex operation,which,to some extent,affected oil production.For this reason,fracturing ball seat has developed from drilling removal to dissoluble process,so that the dissoluble fracturing ball seat will dissolve automatically after work completion without drilling removal,which greatly saved time,reduced cost and enhanced the efficiency of oil production.At present,dissoluble fracturing ball has achieved extensive application,but the development of dissoluble fracturing ball seat is relatively slow,so to study dissoluble fracturing ball seat is critically significant.During fracturing,the inner surface of dissoluble ball seat may suffer erosion damage by flowing liquid,which could result in the premature failure of ball seat.Therefore,the dissoluble ball seat which be studied in this paper shall be able to dissolve automatically while meeting the fracturing conditions.It is possible to research the erosion and abrasion resistant performance of dissoluble ball seat through simulation of fluid analysis software and experimental study,so as to design a dissoluble soluble ball seat.According to the fracturing series and experimental requirements,the structure of ball seat is designed and analyzed.Fluid analysis: Fluent fluid analysis software is used to analyze which parts in the inner wall of ball seat will be damaged by erosion,obtaining the factors affecting erosive wear rate of dissoluble ball seat,and analyzes the relationship between ball seat erosive wear rate and ball seat cone angle,inlet velocity,sand content ratio as well as sand particle size.Numerical simulation finds that the ball seat structure with cone angle of 30°suffers the lowest erosive wear,and the part in serious erosive wear locates in the contact surface of cone section and throat section,and the surface of throat section.Experimental analysis: The experimental program and the test bench are established for scouring experiment of dissolvable ball seat,which concludes that the ball seat with cone angle of 30°is the most seriously affected by erosion and it accords with the conclusion acquired by numerical simulation.In order to slow down the erosion rate suffered by ball seat,the wear-resistant coating is sprayed on the inner surface.After experimentally comparing the properties of WC-CO coatings and Al₂O₃ ceramic coatings,Al₂O₃ ceramic coating is selected as a wear-resistant coating of dissolvable ball seat.