The Effect of Changes in Hydraulic Fracking Fluid Chemistries on theDissolution Rate of Dissolvable Magnesium Frack Plug Components

摘要

Objectives/Scope:The use of dissolvable metal technologies for use in downhole tools for the hydraulicfracking industry has expanded rapidly over the last few years.The dissolution rate of these alloys is knownto be sensitive to the chemistry of the fracking fluids used.Recently,there has been a drive to increase the useof recycled fracking fluid,resulting in unintended changes to the fluid chemistry.This work will review theeffect of such changes in frac fluid chemistries on the dissolution rate of commercially available magnesiumbased dissolvable alloys.These results are compared to the published dissolution rate for the same alloys.Methods,Procedures,Process:The published rate of dissolution is based on tightly controlledtemperatures,utilising KCl solutions typically up to 3 % KCl.In this work,the dissolution rate was measuredfor a range of simulated frac fluid chemistries.Tests were carried out in tightly controlled laboratoryconditions at ambient pressures and at temperatures up to 200 F.A range of brine solutions were investigated,applying systematic changes to the compositions of each solution.This approach provided reproducibleconditions,allowing the effect of specific species typically found in downhole frac fluids to be isolatedand evaluated.Results,Observations,Conclusions:The results show clear trends on the dissolution rate of dissolvablemagnesium alloys with changes in frac fluid chemistry.In particular,the presence of certain salts haveshown to significantly reduce the material dissolution rate.Novel/Additive Information:While the general trend for increased dissolution rate with increasing brineconcentration is well understood it was surprising to find a decrease in corrosion rate where certain saltsare present.These results are invaluable in providing the operator a greater understanding on the expecteddissolution rate of dissolvable magnesium technologies within the field for a given chemistry of frac fluid.These results are of particular importance given the trend towards reuse of frac fluids in the field.