Inverse Emulsion Polymerization Of Polyacrylamide And Its Development And Test As Recoverable Fracturing Fluid

In recent years,the output of polyacrylamide in China has gradually increased and more than 60% of it has been used in the development of oil and natural gas.According to the evaluation of the existing fracturing fluid system in Changqing Oilfield and the investigation of geological and on-site construction conditions in Changqing Shenmu Gasfield.This paper proposes the idea of using inverse emulsion synthetic polymer as fracturing fluid and recycling and recycling the return fluid.On the one hand,it decreases the use of river water and groundwater by fracturing,and cuts down the cost of water for fracturing fluid.On the other hand,it decreases the sewage of the whole oil production system.In this experiment,acrylamide(AM),acrylic acid(AA),and 2-acrylamido-2-methylpropanesulfonic acid(AMPS)are used as polymeric monomers,introducing a salt-tolerant functional monomer.Based on polymer chemical polymerization,this experiment uses molecular structure design to synthesize emulsion polymer,by inverse emulsion polymerization.It can quickly hydrate,break,dissolve and thicken when it meets water.Through this experimental study,the following conclusions can be drawn:1)By optimizing the functional monomer,S-18 is compatible with the emulsion and can be used as a salt-tolerant functional monomer.The author optimized the emulsion system and determined the alkanolamide oleic acid M83 VG as the main emulsifier formula.On the basis of the emulsifier formula,the author optimized the amount of emulsifier,monomer molar ratio,mole number of polymerized monomers,initiator system and dosage,reaction temperature and reaction time,and obtained the final laboratory formula.The formulation conditions are that the emulsifier accounts for 3.2% of the total mass fraction,the degree of hydrolysis is 40%,the mass fraction of the polymerized monomer is 33%,the reaction temperature is controlled at 42-45 ° C,the initiator accounts for 0.03% of the total mass and the optimum reaction time is 4 hours.The pilot test is carried out to amplify the production test.The product characteristic index meets or exceeds the laboratory sample,indicating that the pilot reproducibility is good.At the same time,due to the absence of three wastes in emulsion polymerization,the formulation meets the requirements of safety and environmental protection and is suitable for industrial production.2)For By analyzing the nuclear magnetic infrared detection of the product,the sulfonic acid group shows its own unique peak and chemical shift of adjacent hydrogen.Functional monomer S-18 is grafted onto the polymer molecular chain consistent with the expected molecular structure.The XRD diffraction test results of the emulsion polymer indicate that the polymer is not crystalline structure and therefore the polymer has higher solubility in water.By observing the microscopic state of the polymer by SEM,a dense three-dimensional space network is formed in the aqueous solution space.The molecular chains are closely entangled with each other,so that the PEM polymer has good temperature and shear resistance.3)Through laboratory experiments,the emulsion system has good performance and short dissolution time.It can quickly hydrate and thicken.The viscosity of the sand-carrying liquid is 87mPa·s,the suspended sand performance is good,the drag reduction rate is above 60%,and the compatibility with the helper is good.After degradation,the viscosity is less than 5 mPa·s.Shearing the degradation solution,the result showed no foam.4)Field application test in the double C22 well of Shenmu gas field,the product can meet the technical requirements of continuous compounding process;using the returning liquid to reconstitute the fracturing fluid,Under the condition that the sand ratio is 25%,the construction is stable.The return rate is over 50%,there is no foam in the return row and the ignition is successful.