Study On The Preparation Of Drilling Fluid Using Fracturing Flowback Fluid

In this paper,the drilling fluid was mainly prepared by mixing the guanidine gum fracturing flowback fluid and the clean fracturing flowback fluid and the different proportions of the base mud,which own nice inhibition property.The stability of drilling fluids was maintained by adding glue,under the optimal mixing ratio conditions,the orthogonal test was carried out under different glues with the performance of each drilling fluids as the evaluation index,so that the optimal formula of the drilling fluids was prepared by fracturing flowback fluid.The linear expansion rate of bentonite and the mud ball test were used as evaluation indexes to evaluate the inhibition of the drilling fluids prepared by the Guar Gum fracturing flowback fluid and the clean fracturing backflow liquid.The inhibitory mechanism was investigated by means of laser particle size,scanning electron microscopy(SEM)and thermogravimetric analysis(TG).(1)The low-viscosity CMC,CMC,medium-viscous CMC,and HV-CMC were used as the glue protecting agent,the optimal mixing ratio of the guanidine gum fracturing flowback fluid and different proportions of the base mud was 4:1,4:1,3:1,3:1,respectively.Through orthogonal experiment,range analysis and single factor experiment,the best formula for preparing drilling fluids for backflow liquid was obtained: 1.5% LV-CMC + 1.5% modified plant phenol + 0.01% polyaluminum chloride + 0.3% heteropolysaccharide lubricant,the performance of the formulated drilling fluidss meets PV 3~15 mPa·s,YP 2~10 Pa,tg? 0.08,FL? 6.0 mL.The low-viscosity CMC was used as glue protecting agent,the drilling fluids prepared by guanidine gum flowback fluid had better performance of the drilling fluids at 150 °C,and the temperature resistance was the best.The result of the linear bentonite swelling experiment and the mud ball experiment presented that the drilling fluids prepared by the fracturing backflow liquid and its supernatant have a good inhibitory effect on the hydration expansion of clay.At 30 °C,CMC was used as the glue protecting agent,the drilling fluids prepared by the guanidine gum fracturing flowback fluid and its supernatant have the best inhibitory effect on bentonite.At 120 min,the linear expansion rates were 10.55% and 12.42%,respectively.At 90 °C,HV-CMC was used as the glue protecting agent.The drilling fluids prepared by the guar-capped fracturing fluid and its supernatant had the best inhibitory effect on bentonite.At 120 min,the linear expansion rates were 16.98% and 18.43%,respectively.(2)The xanthan gum,guanidine gum,CMC,HV-CMC were used as the glue protecting agent,the optimal mixing ratio of clean fracturing flowback fluid and different proportions of the base mud was 3:1,2:1,4:1,4:1,respectively.Through orthogonal experiment,range analysis and single factor experiment,the best formula for preparing drilling fluids for backflow liquid was obtained: 1.0% modified rubber powder + 0.20% guanidine gum + modified plant phenol-polyaluminum chloride compound ratio 1.5:0.01 + 0.4% polymeric alcohol lubricant;1.0% modified rubber powder + 0.20% CMC + modified plant phenol-Polyaluminum chloride compounding ratio 1.5:0.03 + 0.4% heteropolysaccharide lubricant,the performance of the formulated drilling fluids meets PV 3~15 mPa·s,YP 2~10 Pa,tg? 0.08,FL? 6.0 mL.The CMC was used as glue protecting agent,the drilling fluids prepared by the clean fracturing flowback fluid had better performance of the drilling fluids at 150 °C,and the temperature resistance was the best.The result of the linear bentonite swelling experiment and the mud ball experiment presented that the drilling fluids prepared by the clean fracturing backflow liquid and its supernatant have a good inhibitory effect on the hydration expansion of clay.At 30 °C,CMC was used as the glue protecting agent,the drilling fluids prepared by cleaning the fracturing and returning liquid and its supernatant had the best inhibitory effect on bentonite.At 120 min,the linear expansion rates are 7.71% and 12.94%,respectively.At 90 °C,HV-CMC was used as the glue protecting agent,the drilling fluids prepared by the clean fracturing flowback fluid has the best inhibitory effect on bentonite;At 120 min,the linear expansion ratio was 20.66%.The xanthan gum was used as the glue protecting agent,the drilling fluids prepared by the clean fracturing flowback fluid has the best inhibitory effect on bentonite.At 120 min,and the linear expansion ratio was 24.81%.(3)Inhibition characterization results demonstrates that the potassium chloride contained in the guanidine gum fracturing flowback fluid can be adsorbed into the clay layer by montmorillonite,and the hydration energy of potassium ions is relatively low,which makes hydration difficult;The water molecules originally in the interlayer will be excluded from the layer,which will have a better inhibitory effect on the hydration expansion of the bentonite.The clean fracturing flowback fluid contains quaternary ammonium salt,and the quaternary ammonium salt belongs to the long-chain molecule,which is mainly adsorbed on the surface of the clay,thereby having a good inhibitory effect on the hydration expansion of the bentonite.