Synthesis And Performance Evaluation Of Oil Field Squeeze Anti-scaling Agent

With the increase of oilfield exploitation time,the production and quality of oil wells have continuously declined,and even the production shutdown problem has arisen.In order to increase the oil recovery rate and increase the reservoir pressure,it is necessary to develop the oilfield with water injection.However,in actual production,fouling phenomena are bound to occur in the process of water injection,such as formation pore blockage,pipeline fouling,and wellbore fouling.In the process of cleaning dirt with water,a large amount of sewage with complex components will be generated,which will cause environmental impacts.Big hazards.Therefore,the study of anti-scaling can reduce the discharge of sewage from the source,which is crucial to environmental issues.By contrasting with other anti-scaling technologies,this paper adopts a squeeze injection and anti-scaling technology widely used in foreign oilfields.It can systematically suppress fouling in near-wellbore,wellbore,and surface gathering and transportation equipment,and has anti-fouling effectiveness.Long life,simple operation and other advantages.At present,there are many problems and limitations in the application of scale inhibitors in oil fields.Therefore,this article uses acrylic acid(AA)and methacryloyl oxygen according to the characteristics of negatively charged rock surfaces in sandstone oil reservoirs and the requirements of squeeze inhibitors(high anti-scaling efficiency,easy detection,and strong adsorption and retention capacity).methacryloyloxyethyl trimethyl ammonium chloride(DMC)and sodium hypophosphite(SHP)were used as raw materials,and ammonium persulfate was used as the initiator to synthesize an extrusion inhibitor PADS suitable for sandstone oil field reservoirs using an aqueous solution radical polymerization method.By examining the effects of monomer concentration,monomer ratio,initiator loading,reaction temperature,reaction time,and the amount of sodium hypophosphite added on scale and molecular weight,each factor was adjusted and optimized using single factor and orthogonal experiments.The optimal synthesis conditions were determined:monomer concentration 30%,AA:DMC 20:2,initiator addition 1%,reaction temperature 70?,reaction time 3 h,sodium hypophosphite addition 5%,and infrared use Spectral and nuclear magnetic resonance were used to characterize the structure of PADS.The spectrum analysis confirmed that the target product was synthesized.With reference to the water quality of the Weizhou 12-1 oilfield block,experimental simulated water was formulated.The anti-fouling performance of the PADS was investigated from the aspects of addition volume and temperature,and the compatibility of PADS and formation water was studied.The experimental results show that when the scale inhibitor PADS dosage is 20mg/L,the anti-scaling rate of calcium carbonate is higher than 85%,which meets the application requirements of scale inhibitor in the oil field.When the addition amount is 35mg/L,the anti-scaling rate reaches 93.07%,with excellent anti-fouling effect;the anti-scaling effect of PADS increases first and then decreases with increasing temperature;combined with scanning electron microscopy analysis,PADS is mainly used to prevent scaling through lattice distortion and dispersion;PADS has good antifouling effect on barium sulfate scale.The higher the temperature,the stronger the ability to inhibit barium sulfate scale.When the temperature is 90?,the anti-scaling rate of barium sulfate reaches 85.31%;it has good compatibility with the formation water of the Weizhou 12-1 oil field.The adsorptive retention of anti-scaling agent PADS on sandstone surface was evaluated by static adsorption experiments and core dynamic adsorption-desorption experiments.The visible spectrophotometric method was used to measure the concentration of antifoulant in real time,and the oil scale control sample MS was used.Comparative Experiment.The experimental results show that the static adsorption capacity of PADS is about 3.23 times that of MS.The static adsorptioncapacity of PADS and MS on sandstone decreases with increasing temperature.The adsorption capacity of PADS on sandstone is still at 80?.Maintaining 3.2 mg/g,which is much larger than that of MS,0.74 mg/g;the adsorption isotherms of PADS and MS were fitted to the Langmuir adsorption model;the amount of anti-scaling agent adsorbed on quartz sand increased,with the content of sodium chloride.The increase,up to 2%,remains stable;under the same conditions,the dynamic adsorption capacity of PADS on sandstone is better than that of MS,and the extrusion life is 1.69 times that of MS;the increase of temperature and flow velocity of fluid will shorten the MS.Extrusion life;the increase in initial injection concentration has a limited effect on increasing the extrusion life of PADS in sandstone.Based on the analysis of the basic data of Weizhou 12-1 oil well,combined with the indoor laboratory results and the relevant extrusion parameters,the dosage of each chemical in the on-site construction process was determined,and the on-site construction and effect evaluation were performed.The anti-scaling agent PADS had good on-site injection property,squeeze life up to 1 year.