Synthesis And Interaction Mechanism Of A Low Interfacial Tension Fracturing Fluid

Fracturing technology is a technique of increase the output, whichcommonly used in domestic and international oilfield. The one of core content ofthe fracturing technology is fracturing fluid, which is the conclusive factor forthe incensement of the output in oilfield. Guar gum is one of the thickeningagents used commonly in oilfield’s fracturing technology for its excellentthickening performance and gel breaking performance, but the drawback of theresidue content was too higher to block the oil layer, which was the main reasonto prevent the guar gum widely used in oilfield. For the modified guar gum, thefracturing fluid with low interface tension will be an important research area infuture. Because low interface tension could reduce the flow friction resistanceand the hurt to the oil layer, furthermore, the residue content was lower,performance was greatly improved, and pollution was reduced. This paperresearched a novel fracture fluid with low interface tension on this basis.The modified guar gum fracture fluid, which contained several hydroxylgroups and carboxyl group, was synthesis by guar gum and alkenyl succinicanhydride (ASA) through esterification. Then we characterized the structure ofguar gum through Fourier transform infrared spectroscopy (FT-IR), X-raydiffraction, thermo gravimetric analysis (TGA) and scanning electronmicroscope (SEM). The characterization result indicated that the ASA wasesterified with guar gum successfully. We researched the optimal reactioncondition, such as reaction time, reaction temperature, the ratio of reactant,amount of catalytic agent and water through single factor optimization method,and the result showed that the optimal reaction time was10hour, the optimalreaction temperature was60centigrade, the optimal ratio of reactant was7:1, theamount of NaHCO3was4%of the total mass, the dosage of water was4%of thetotal mass. In the optimal condition, the water-air interface tension of reactionproducts was35.29mN/m as the concentration was4%. The water-air interface tension of breaked gel of products was29.65mN/m, and the kerosene-waterinterface tension of breaked gel was2.27mN/m. Moreover, the properties ofviscosity of gel, proppant carrying capacity, heat resistance performance, shearresistance performance and friction properties was researched about modifiedguar gum after crosslinking by organoboron compound. In addition, the residuecontent was measured after the gel breaked by ammonium persulfate. The resultshowed that the viscosity of gel was125mPa·s, the viscosity of breaked gel was2.2mPa·s, the residue content of breaked gel was300mg/L, which was lowerthan guar gum and hydroxypropyl guar, the water-air interface tension ofcolatuie was29.25mN/m, the kerosene-water interface tension was2.27mN/m.In addition, the modified guar gum has good pick-hanging performance and sandcarrying performance, and heat resistance and shear resistance performance wasenhanced than guar gum, friction properties was lower than guar gum.Furthermore, we investigated the performance of fracture fluid in oilfield, theresult showed that the modified guar gum fracture fluid could meet therequirements with a good prospect of application.