The Research And Application Of Molecular Film Augmented Injection Technology In Tuha Oil Field

Tuha Oil-field is a representative low permeability oil reservoir. Water injection is the main development mode in the initial stage.The injection pressure has been ascending by the affection of well pattern arrangement and reservoir physical properties and water quality in downhole. There are30%water injection wells that are under the production proration with35Mpa well injection pressure in Shanshan and Qiuling oil field. Previous conventional hydraulic fracturing and acidizing are shortcomings and drawbacks of each. The effect of application is worse year by year. There are134wells finished by acid stimulation in Tuha oil field in2011. The active rate is only90%and the average well extra injection is25cubic meter. The effective period is100days. So it is an important issue for low permeability reservoir to research a new efficient method of flooding.Both inside and outside contamination facters of water injection wells are dicussed on the case of the reasearch of resvoir physical properties. This paper has assessed the acid stimulation effects over the years and summed up the technology suitability of traditional acid technic and pointed out the traditional acid technic limitation, which provides the basic guiding theory of the reaserch and design of molecular augmented technology.This paper proposes a new technology of injection enhancement-molecular film. Applies the molecular film technology in water-injection well’s technology of injection enhancement, is precisely based on the molecular film displacement of reservoir oil technology. Molecular film is one kind of molecular film, takes 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. Molecular 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 molecular film augmented injection mechanism is that molecular film peels the water film of pore surface, the wettability changed a hydrophilic into hydrophobic.This paper infrared spectrometer on the molecular film structures were characterized, indicating that molecular 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 molecular the membrane can cause the hydrophilic surface to the sparse square water pitcher to the transformation.We also studied molecular film’s physical and chemical properties, established the molecular 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 molecular film flooding agent by measuring of the film surface tension of aqueous solution, we can see that, molecular membrane contains surface active substances, can reduce the surface tension of aqueous solution, but not surfactant.(2)Using Static coupon, determined corrosion of molecular solution to meet site requirements, and molecular film has good stability.(3) Molecular solution in the sand column surface than the regular anti-swelling agent has better dynamic ability to inhibit the migration of clay particles; molecular 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 Tuha oilfield natural core use constant displacement method, to know core relative permeability changes before and after treating with molecular film. The results show that, molecular film has a strong ability to increase water permeability.We studied molecular depressurizing and injection enhancement mechanism, analysed and calculated the role energy between the water and the hole wall of the rock, molecular film and the hole wall of the rock, the main conclusions are:(1)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) Molecular membrane from the aqueous layer to adsorb 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 molecular membrane and the pore wall is much larger than between water and the pore wall. Molecular film is in the dominant in the competitive adsorption, so molecular film will replace the hydration layer adsorbed on the pore walls.(4) Molecular membrane breakthrough the hydration layer and the competitive adsorption pore wall is the critical in replacing hydration layer and creating adsorption layer, the electrostatic interaction is the main role.(5)After molecular 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 molecular film easily penetrates and adsorbs into the pores of the rock surface to change the wettability and reduce the adhesion work pore surface to the water.By core displacement experiments, investigate effect of molecular film concentration and displacement volume and reaction time on the wettability of cores. Study the treatment effect of the water quality, determine molecular film’s best absorption environment. The main conclusions are:(1) Molecular 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 molecular 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, molecular acid membrane and pre-test also showed that composite technology The technology can effectively improve the core permeability. Laboratory determined processing fluid formula of Shenquan oil area:(1) Treatment fluid A:10%HCL+1.5%retarder agent+1.5%clay stabilizer+1%iron stabilizer+0.5%surfactant.(2) Treatment fluid B:15%HCL+3%HF+2%retarder agent+1.5%clay stabilizer+1%iron stabilizer.(3) Treatment fluid C:10%HCL+1.5%retarder agent+1.5%clay stabilizer+1%iron stabilizer. (4) Treatment fluid D:2%molecular solution+0.25%surfactant A+0.1%surfactant B.The fluid formula of Shanshan、Qiuling and Wenmi oil area:(1) Treatment fluid A:10%HCL+1%retarder agent+1.5%clay stabilizer+1%iron stabilizer+0.5%surfactant.(2) Treatment fluid B:0.5%YL-3acid agent.(3)Treatment fluid C:12%HCL+3%HF+2%retarder agent+1.5%clay stabilizer+1%iron stabilizer.(4)Treatment fluid D:2%molecular solution+0.30%surfactant A+0.1%surfactant B.(5) Treatment fluid E:1-2%YM-1.Through experiments constituencies and program optimization, we carried out pre-acid composite membrane molecular single well test and effect of increasing injection. Field test shows that, molecular membrane had a marked effect on reducing the pressure of injection wells.