Research On Cementing Water-based Epoxy Resin Cement Slurry

Epoxy resin is gradually used as a new material in oil and gas well cementing engineering.As an organic polymer material,epoxy resin is expensive.Therefore,mixing inorganic materials such as oil well cement slurry with epoxy resin to solve the problem of price and cost has gradually become a research trend.Based on literature research,a kind of waterborne epoxy resin suitable for oil well cement slurry was screened out from two kinds of waterborne epoxy resin widely used.According to the comprehensive performance evaluation of conventional resin cement slurry,it is found that different proportions of epoxy resin have great influence on the fluidity,density,thickening time and mechanical properties of conventional resin cement slurry.Among them,60%of resin cement has a 28-day compressive strength of 51 MPa.Compared with oil well cement,it increased by 47%.The elastic modulus of resin cement paste with 60%resin is as low as 1.8 GPa,which is 76.5%lower than that of oil well cement paste.It can form "high strength,low elasticity" resin cement paste.Aiming at the shortcomings of conventional resin cement stone,such as poor fluidity,density,iradjustable thickening time,and inability to form strength in some mixtures.By optimizing curing agent,diluent,filling material and ratio,a set of resin cement slurry system with adjustable density range of 1.35-2.2 g/cm3,adjustable curing time of 30-175 min at 90?,compressive strength of 48h over 30 MPa was formed,and the water loss of resin cement slurry was less than 50 mL at different temperatures,with good sedimentation stability and fluidity of more than 18 cm.Due to the large amount of epoxy resin added,the cured resin cement paste shows elastic-plastic,so it is difficult to evaluate the resin cement paste comprehensively by using the traditional mechanical evaluation method of cement paste.Because of the glass transition temperature of epoxy resin,the mechanical properties of epoxy resin will be affected by thermal deformation after high temperature.Therefore,this paper evaluates the mechanical properties of resin cement paste from three aspects:compressive bearing capacity,elastic bearing capacity and cementing strength by simulating the temperature in the well.The experimental results show that the strength of resin cement paste decreases by more than 30%at high temperature.By means of X-ray diffraction analysis,nuclear magnetic resonance and scanning electron microscopy,it was found that no new products were produced by the incorporation of resin.The results of NMR experiments show that the porosity of oil well cement paste decreases from 10.9%to 4.2%,and the decrease is as high as 61%.The results of scanning electron microscopy(SEM)experiments show that the resin mainly relies on the three-dimensional network structure formed after curing,and encapsulates the cement hydration products to form a structural deformation center with certain strength,which can restrain the generation and development of micro-cracks and absorb strain energy.The waterborne epoxy resin cement slurry system studied in this paper can significantly improve the mechanical properties of oil well cement paste,which is of great significance to improve the mechanical properties of oil well cement sheath.