Structural Optimization Research Of Expandable Sand Screen

During the development of unconsolidated sandstone reservoir,sand production has become an important risk in well-working rate and output per-well,leading to frequent workover operations as well as casing deformations and failures.It is obvious that the traditional sand control liner has these disadvantages,such as a short period of sand control and a small inner diameter,which both could influence well productivity and also could increase the difficulty in further workover operations.The expandable sand screen(ESS)developed recently is a new sand control method.After the well completion,the expandable sand screen is expanded onto the internal wall of casing or wellbore and it can improve the productivity of oil and gas well,reduce the casing damages and make the sand control effective in a longer period.In this paper the optimization research of the slotted pipe have been carried out,in order to improve the structural design theory of ESS.The mechanical model of the axial thrust and the slotted pipe is established based on elastic-plastic mechanics during the expansion process;the axial thrust variation with the axial displacement is obtained when the different structure of slotted pipe is expanded,as well as the distribution of the crack-tip maximum stress in the thickness direction after the expansion by using the ABAQUS;based on linear response surface optimization method the optimal slotted pipe structure is obtained.The optimal design is as follows: the slot is staggered arranged axially,the length is 110 mm,the width is 1mm,the slot number is 12 in the circumferential direction.The laboratory experiment results showed that: the maximum axial thrust of the optimal pipe structure is 56.44kN;the theoretical value is 61.54 kN,the error is 9.04%;the numerical simulation results is 51.78 kN,the error is 8.26%.Both mechanical model and numerical simulation method can provide theoretical support for the structural design of ESS.Based on the laboratory experiment,the field test was carried out.The ESS was expanded onto the inner wall of 7in casing,the diameter is ?138mm,the expansion rate is 56.8%.Compared with traditional screen the inner diameter after completion increased by 30%,the daily fluid production increased by 50%,validity period of sand control increased by three times.