Particle Size Analysis And Plugging Performance Evaluation Of Micro/Nano Plugging Materials

In drilling process,especially in shale which contain large amounts of micro and nano pores,the drilling fluid or filtrate through these micro and nano pores into the formation,will lead to shale hydration and other issues,so it is important to prevent the drilling fluid or the filtrate from entering the formation through these micro and nano pores,and how to solve this problem is a technical conundrum.In view of the current situation that we have so many kind of nano-level blocking agent in drilling fluid and less evaluation methods and other issues,it is important to study the particle size distribution of the plugging agent in the drilling fluid and simulated the shale micro and nano pores to evaluate the occluder.Studied the decentralized performance of four common nanometer powder plugging agents,through the scanning electron microscopy(SEM)observation,Zeta potential test and particle size distribution test,the nano-silica and nano-calcium carbonate with smaller particle size and higher stability were selected for the next dispersion experimental study.The experiment have investigated the physical dispersion method and chemical dispersion method on the decentralized performance of nano-silica and nano-calcium carbonate in aqueous solution.The optimum dispersion process of nano-silica was obtained by experiment.First,stirring at 10,000 r/min for 80 min,while add 2%of the organic anionic dispersant sodium dodecyl benzene sulfonate(SDBS),then ultrasonic processing in ultrasonic cleaners in 5 min,the result showed that nanometer of the nano-silica particle size distribution was concentrated in 0.60?m.The optimum dispersion process of nano-calcium carbonate was obtained by experiment.First,stirring at 10,000 r/min for 80 min,while add 2%of the Inorganic dispersant sodium hexametaphosphate(SHMP),then ultrasonic processing in ultrasonic cleaners in 5 min,we can obtained 0.20?m nano-calcium carbonate,by the way,0.10%inorganic dispersant sodium silicate can make nano-calcium carbonate diameter of 0.87?m.The experiment have investigated the influence of the shale inhibitor,filtration reducer,viscosifier,thinner to the decentralized performance of the nano-silica and nano-calcium carbonate.Paraffin emulsion has good stability,and the particle size distribution between 60 to 70 nm,the drilling fluid treatment agent has little effect on the particle size of the emulsion paraffin.Different drilling fluid treatment agents have different effects on the particle size distribution of nano-silica and nano-calcium carbonate in aqueous solution.The Drilling fluid inhibitor 80A-51,tackifier LV-CMC had little effect on the particle size of nano-calcium carbonate.The effect of PAC-LV on the particle size of nano-silica was not significant too.In the nanometer material solution,these treatment agents were added respectively,and the particle size of the nanometer material was kept below 1?m.Drilling fluid inhibitor NH4-HPAN,inhibitor 80A-51,filtration reducer DFD-140,tackifier LV-CMC,thinner XY-27 and SMK will increase the size of nano-silica,but the particle size is maintained between 1-100?m.Filtration reducer DFD-140,PAC-LV,thinner XY-27,SMK and inhibitor NH4-HPAN also increase the particle size of nano-calcium carbonate,particle size maintained between 1-100?m.Viscosifier XC will make nano-silica and nano-calcium carbonate particle size significantly increased to 100?m or more.The experiment have investigated the factors of the mud cake's permeability.By adjusting the amount of bentonite,Water temperature,stirring speed,mixing time and drilling fluid treatment agent dosage and type,prepared of mud cake that the permeability close to the shale(10-7?m2).And the sealing effect of three kinds of plugging agents with different particle size was tested by the prepared mud cake,obtained the best particle size distribution for blocking the different permeability mud cake.