| As oilfield water flood degree deepen,less oil production Wells,drilling is difficult and high cost problem,the domestic most of the old oil fields,the phenomenon of the moisture content is above 90%,high water content will cause the loss of oil production,oil well pump efficiency to reduce the severe corrosion and pipeline equipment,also will increase the workload of sewage treatment,so by water plugging operation is to improve the oil recovery rate,lower oil field moisture content,is the most effective means of stabilizing oil production.Other water plugging technology at home and abroad according to the data show that less than 50%success rate,water plugging operation will appear a certain degree of negative impact,so the class for sandstone reservoir with big hole formation water production serious development present situation,through the indoor experiment study,developed a solution that can change the macroscopic throats oil-water relative permeability type cation choose water plugging system,the system mechanism and stability of oil water control performance is carried on the thorough analysis and exploration,to resolve the plugging agent application of cross linking,resin and gel plugging agent widespread reservoir plugging agent retention problems such as,water lock effect,A kind of selective water plugging agent was prepared,which has the characteristics of effective water plugging and no oil plugging.For sandstone reservoir rocks usually negatively charged,rock reservoir due to natural fracture or artificially induced fracture after fracturing,acidizing and other development,the formation morphology presents the characteristics of large size,big hole,crack,makes the moisture content is a sharp rise in oil Wells,the oil production decline,can achieve adsorption for rock surface and change of formation oil and water relative permeability to water plugging purpose,preparation of molecular weight is moderate,has a good adsorptive performance of cationic polymers for plugging agent solution type cationic choice.Using acrylamide(AM)and cationic monomer dimethyl diallyl ammonium chloride(DMDAAC)was modified,by aqueous solution polymerization,and through the radical polymerization to synthesize a kind of cationic polymer P-OL as main agent plugging agent,by investigating the monomer ratio,monomer mass fraction,dosage of initiator,reaction temperature and reaction system pH value of P-OL cationic polymer molecular weight and at best the influence law of adsorption temperature,static adsorption effect,using the single factor experiments on synthesis conditions were optimized and the optimum synthetic condition:monomer mass fraction 40%,DMDAAC:AM molar mass ratio is 1:6,amount of initiator,V50 and 0.05%of the total mass,the reaction temperature 45?,system pH value of 7,polymer molecular weight between 1.4 million-1.6 million,for controlling the amount of static adsorption on quartz sand is greater than 1.5mg/g.The selective plugging water of cationic polymer P-OL was preliminarily explored through the core experiment of sand filled pipe,and the residual resistance coefficient of core water and oil phase was analyzed,proving that P-OL has the ability to change the relative permeability of oil and water to a certain extent.P-OL polymer was characterized by infrared spectroscopy,and the synthesized product was determined to be the target product P-OL.The thermogravimetric analysis shows that the P-OL polymer itself has good thermal stability and is suitable for complex oilfield formation environment.But core experiments showed that only single injection of P-OL molecules,the scour resistance and the period of validity is not strong,so according to the selective cation plugging agent commonly used preparation methods,by investigating the distribution system of cationic degrees of comparison,the introduction of ?-NANO meter microspheres alpha filter NANO as auxiliary plugging agent,and cationic polymer P-OL compound preparation solution type cationic choose SCPA water plugging agent system,according to the environmental scanning electron microscope SEM figure,SCPA system compared with cationic polymer P-OL molecular adsorption mechanism in porous media and water plugging performance,the basic performance evaluation and action mechanism of SCPA were analyzed:apparent viscosity measurement was used to explore whether the injectivity of SCPA water plugging agent met the application requirements of oil field;NaCl was used to investigate the salt resistance of SCPA.Langmuir adsorption model of water plugging agent SCPA was established according to the dynamic adsorption isotherm.Before and after treatment were measured by the SCPA quartz sand surface contact Angle,SCPA single molecule adsorbed layer can make quartz sand surface wettability reversal,change the oil and water phase relative permeability,the rocks into hydrophilic by hydrophilic surface,or by the strong hydrophilic into weak hydrophilic,according to research at home and abroad show that the hydrophilic formation on the surface of the water flooding oil recovery effect is best,by changing the wettability of rock surface to achieve steady oil water control;In the core displacement experiment,the change of residual resistance coefficient of oil-water phase injected with polymer P-OL and water-plugging agent SCPA separately and the change of selectivity effect NFFR value were investigated,the oil-water stability and water-water selectivity and scour resistance of the system were further investigated,and the formation type of SCPA suitable for permeability reservoirs was determined.Will plugging agent SCPA was conducted in the al 3-26 Wells field application,according to the erlian oilfield,according to data from the institute of geological SCPA not only effectively reduce the well water content,oil well output and also can guarantee the stability of the produced fluid volume,at the same time,SCPA type in a solution for the future of plugging agent has important guiding significance to the research direction,and other high water cut oil field applications at home and abroad,also has the corresponding reference value. |
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