Design And Mechanical Analysis Of A Dropable Downhole Foam Generator

Foam drive technology is widely used in oil recovery because of its excellent characteristics.The current foam drive technology uses surface foaming to inject into the formation,which cannot guarantee the foam quality.Downhole foaming is to put the foam generator into the downhole foam injection layer,which can reduce the problem of defoaming during foam injection.However,there are few salvageable downhole foam generators currently in use,and the existing salvageable downhole foam generators require replacement of the process tubing column,which greatly increases production costs.The downhole foam generator is expected to be put into the position of 3000～4000 meters downhole,and the salvageable device with the downhole foam generator has the characteristics of high pressure,high temperature and high vibration in the working environment compared with other putting tools,so the original salvage tool can hardly meet the working condition demand.Therefore,it is very meaningful to design a new type of salvageable device with downhole foam generator.The design difficulty of the downhole foam generator salvageable device is that it can be fixed in any position downhole,and rely on the device’s own structure to complete the snap and unpin,sit and unpin in the well.In this paper,according to the above problem and the actual working condition of downhole foam generator,we have designed a salvageable device with it.The device is equipped with the functions of salvageable,seating and sealing.The downhole foam generator salvageable device consists of a salvageable structure,a sealing structure,and a clamping structure.The device is lowered from the wellhead of the water injection column,and after reaching the predetermined position,the device is lifted up to achieve seizure,relying on the pressure difference between the interior of the air bin and the downhole to push the piston to compress the rubber cylinder to achieve sealing.After the foam injection is completed,the center tube of the device is struck down,the pressure inside and outside the air bin is balanced,the lower kava is recovered,and the device is unclipped and unsealed and taken out by salvage tools,so that the foam injection and water injection processes can be completed in the same process column without starting the column,which improves the operational efficiency.Solid Works and ABAQUS software were used to model and numerically simulate the snap structure and seal structure respectively,and to judge the stability of the snap structure and the sealability of the seal structure.At the same time,the parameters of the kawab structure were preferably selected,and it was concluded that the kawab anchoring structure of the downhole foam generator retrievable device can achieve a stable anchoring effect when the tooth top angle of the kawab is 80°,the tooth inclination angle is 75° and the wedge angle is 15°,and at the same time the kawab can provide an upward anchoring force of 153.6k N and a downward anchoring force of 124 k N after seating and sealing.The effect of the parameters of the sealant cylinder on the performance of the sealant cylinder was studied by simulation analysis,and the optimized dimensions of the sealant cylinder were 60 mm in length,70 mm in outer diameter,47 mm in inner diameter,and 60° in end face inclination,and the maximum contact stress of the sealant cylinder at each sealing surface was 36.06 MPa,which met the sealing requirements of the device for stable operation in the well.