Development And Performance Evaluation Of Cutting Agent For Oil-based And Synthetic-based Drilling Fluids

With the exploration and development of shale gas wells,high-temperature and high-pressure wells and deep wells,ultra-deep wells and horizontal wells with complex formations at home and abroad,oil-based drilling fluids have been widely used.As one of the important treatment agents for oil-based drilling fluids,whether or not the cutting agent can maintain effective cutting performance under high temperature and high pressure conditions is the basis for determining the normal operation of the drilling fluid.In view of the problems that the rheology of oil-based drilling fluids is difficult to control during construction,the dynamic and static cutting forces are relatively low,and settlement is prone to occur,a cutting agent suitable for oil-based synthetic-based drilling fluids was formed through quaternary copolymerization.Infrared spectroscopy,thermogravimetric analysis and other characterization experiments,at the same time,the rheology,electrical stability and high temperature and high pressure fluid loss evaluation experiments were carried out.Finally,the mechanism of action was studied by emulsion SEM and particle size analysis.Starting from the performance requirements of the high temperature and high pressure cutting agent,the molecular structure of the polymer cutting agent was preliminary designed,and dimer acid(C₃₆H₆₈O₄),diethylenetriamine(C₄H₁₃N₃),diethanolamine(C₄H₁₁NO₂)were selected And triethanolamine(C₆H₁₅NO)four reactant raw materials,using triethylene glycol monobutyl ether(C₁₀H₂₂O₄)as a diluent,prepared a new type of high temperature resistant suitable for oil-based synthetic base Lifting agent FPR-1.By optimizing the synthesis reaction conditions of the cutting agent,such as the total monomer concentration of the reactants,the proportion of monomers in the synthesis process,the optimal synthesis temperature,the optimal reaction time,etc.,the final determination of the reaction conditions is:40wt%Concentration,monomer molar ratio(dimer acid OAD:diethylenetriamine DETA:diethanolamine DEA=1:1:0.34,dimer acid OAD:diethylenetriamine DETA:triethanolamine TEA=1:1:1),The reaction temperature was 165?and the synthesis reaction time was 3h.Characterization experiments such as infrared spectroscopy and thermogravimetric analysis of the polymer products show that FPR-1 contains all groups polymerized by the selected monomers,while the cutting agent can still be effective under high temperature conditions Lifting performance.The experimental results of FPR-1 rheology,demulsification voltage,and high temperature and high pressure fluid loss evaluation show that the cutting agent FPR-1can significantly enhance the dynamic and static cutting force and demulsification voltage of the oil-based drilling fluid,and the dynamic cutting force is increased from6Pa to 12Pa The demulsification voltage is up to 1496V,which enhances the stability of the emulsion and the shear force of the system.The thickness of the filter cake is observed to be thin,and its temperature resistance can reach 220?.Therefore,the difficulty of drilling a part of the drilling fluid with high temperature and high pressure formation failure has important guiding significance for the development of deep wells and ultra-deep wells.The action mechanism of FPR-1 cutting agent was analyzed by means of emulsion SEM analysis and drilling fluid particle size analysis.The results show that the space grid structure formed by FPR-1 can effectively prevent the coalescence of molecular particles and make the oil and water in the base slurry The distribution of molecular particles is reasonable,which can enhance the stability of the emulsion and play a lifting effect.