| WenMi Oil-field has extensive oil reserves in low permeability reservoir, water injection is the main development mode in the oil region.The low permeable reservoir of this oilfield has the problem of ascending of injection pressure and difficulty of water injection. Therefore,the key is to research for the technologic measures of descending injection pressure and improving augmented injection effect.Previous Depressurizing and Injection Enhancement method(mainly hydraulic fracturing, acidizing, layer of gas by injection, injection of silicon nano-poly, etc.)are shortcomings and drawbacks of each. So finding a new green environmental protection and efficient method of flooding has become an important issue to be settled urgently.This paper proposes a new technology of depressurizing and injection enhancement-depressurizing and injection enhancement of YMD film. Applies the molecular film technology in water-injection well’s technology of depressurizing and injection enhancement, is precisely based on the molecular film displacement of reservoir oil technology.YMD film is one kind of molecular film, take the peroxide solution as the transmission medium,film depend on the molecular electrostatic driving force for film, the membrane medicinal preparation effective member deposition is assuming the electronegativity rock surface, changing the nature of the reservoir surface. YMD film adsorbed on the surface of the rock, expels the rock surface’s water film, causes the fluent channel to increase, thus reduces the water injection pressure.The difference between YMD film augmented injection mechanism and mechanism of molecular films drives is that YMD film peels the the water film of pore surface,the wettability changed a hydrophilic into hydrophobic, and molecular films drives dissects the oil film of pore surface, the wettability changed the hydrophobic into hydrophilic.This paper infrared spectrometer on the MD film structures were characterized, indicating that YMD membrane molecules contains methyl, methylene and hydroxyl groups and nitrogen cation quarter,the polymer is a molecule with a hydrophobic side chain poly quaternary ammonium groups..Measurement of wetting angle data show that YMD the membrane can cause the hydrophilic surface to the sparse square water pitcher to the transformation.We also studied YMD film’s physical and chemical properties, established the YMD membrane performance evaluation method. The main contents are:(1)We used the intravenous contacted angle of A101automatic surface/interfacial tension measuring instrument for evaluating, we evaluated the performance of the YMD film flooding agent by measuring of the film surface tension of aqueous solution,we can see that,YMD membrane contains surface active substances, can reduce the surface tension of aqueous solution, but not surfactant.(2)Using Static coupon, determined corrosion of YMD solution to meet site requirements, and YMD film has good stability.(3) YMD solution in the sand column surface than the regular anti-swelling agent has better dynamic ability to inhibit the migration of clay particles; YMD solution in the clay surface to form the effective monolayer, inhabit the clay swelling,It has some anti-swelling effect.(4) Carried injection evaluation experiments to Haita oilfield natural core use constant displacement method,to know core relative permeability changes.before and after treating with YMD film. The results show that, YMD film has a strong ability to increase water permeability.We studied YMD depressurizing and injection enhancement mechanism, analysised and calculated the role energy between the water and the hole wall of the rock, YMD film and the hole wall of the rock,the main conclusions are:(l)Pore surface of the rock formation of the hydration layer, the thickness of the hydration layer is less than5nm, the inner layer of water molecules has the role of the paradigm and use of hydrogen bonding, the role of energy levels for the10"20J, mainly hydrogen bonding interaction.(2)YMD membrane from the aqueous layer t into adsorping the rock pores surface, subjected a variety of roles energy, including electrostatic interaction, pattern effect, Brownian random effects and multiple hydrogen bonding. At5nm away from pore wall, the role energy levels of10-18J, at0.3nm away from pore wall, the role energy levels of10-17J.(3)The roles energy between YMD membrane and the pore wall is much larger than between water and the pore wall.YMD film is in the dominant in the competitive adsorption., so YMD film will replace the hydration layer adsorbed on the pore walls.(4)YMD membrane breakthrough the hydration layer and the competitive adsorption pore wall is the critical in replacing hydration layer and formating adsorption layer, the electrostatic interaction is. The main role.(5)After YMD film adsorbed on the rock walls of the pores, the hydrophobic groups stretching of molecular film side chain arranged side by side, in the hole wall surface form a arrange which hydrophobic molecule body is in order.from outside the bundle the ordered arrangement hydrophobic surface changes the reservoir’s wettability, making the reservoir surface wettability change from hydrophilic to hydrophobic.(6)Adsorption experiments showed that, YMD film easily penetrate and adsorp into the pores of the rock surface, change the wettability, reduce the adhesion work pore surface to the water.By core displacement experiments, investigated effect of YMD film concentration and displacement volume and reaction time on the wettability of cores. Studied the treatment effect of the water quality, determined YMD film’s best absorption environment. The main conclusions are:(1)YMD membrane concentration is2000mg/L and the adsorption time in full rock surface is24hours or more and displacement volume is1PV, the effect of improving core permeability is the most. The injection of water quality will directly affect the treatment effect.(2)Added pre-film liquid before YMD membrane solution in the injection,it is better to the effect of injection enhancement.By the core and rock powder acid test,, the clay stabilizer anti-swelling experiment, hydrochloric acid corrosion inhibitor performance evaluation experiment, determined the pre-acid formula and acid additives, YMD acid membrane and pre-test also showed that composite technology. The technology can effectively improve the core permeability. Laboratory determined processing fluid formula of Haita oilfield301well area, and Bell oilfield are:Through experiments constituencies and program optimization,we carried out pre-acid composite membrane YMD single well test and effect of increasing injection. Field test shows that, YMD membrane had a marked effect on reducing the pressure of injection wells. |
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