Carbonate Reservoir Pore Structure And Wettability Reversal Effect On Seepage Law Research

In this paper,using a variety of experiment method to analyze rock composition and pore structure,including reservoir mineral composition analysis experiment,CT scans,the casting thin sections,the like microscopic experiment,conventional mercury injection experiment,constant speed mercury injection experiment,etc.Study of reservoir wettability reversal,including wettability evaluation test,high temperature and high salt chemical stability experiment,thin calcite test reverse wetting ability,natural core permeability displacement experiments,etc.On the basis of relative permeability of chemical flooding has carried on the research and application,the calculation methods of reservoir core for the determination of oil and water relative permeability curve and stress sensitivity experiments.Thesis adopt the method of indoor experiment and theoretical research,obtained the following results:1.Y reservoir S group and L.F core determination of chemical composition,calcite as the main mineral composition of the reservoir.Visual observation on the core,determine the karst cave reservoir development,for 1?2 cm in diam.CT scan to determine the core pore formed by holes,holes,seams,irregular shape,size;Casting thin-section analysis of pore types have primary intergranular pores,intergranular dissolved pore,intercrystalline pore and micro cracks,etc.Otard microscopic observation experiment carbonate core crystal particle shape consistency is poorer,the pore space are mainly composed of dissolved pore,primary intergranular pore is complementary,compared with sandstone pore shape,the dissolution is obvious.2.According to the permeability of reservoir can be divided into 3 groups,conventional mercury injection for different types of reservoir pore radius distribution,morphology and the parameters of the reservoir characteristics of capillary pressure curve were analyzed,and the various types of reservoir capillary pressure curve to carry on the average I class reservoir properties,best ? class hierarchy of storage,? kind of reservoir is the worst.Constant speed mercury penetration to determine the different types of pore and throat,pore throat than their respective distribution and numerical fitting relationship.3.Y reservoir wettability cores for oil wet,through high temperature and high salt stability test,calcite chip test reverse wetting ability,natural core permeability,displacement experiments,down 0.3wt%MOA9 surfactants effect is best,can improve the permeability recovery rate 18.78%,the absorption process of surfactant flooding to improve ultimate recovery 11.11%,surfactants in permeability and absorption displacement process,improve the recovery factor of 28.89%achieved good results.4.Mutual transformation,the methods for characterizing the wettability will commonly used said Amott wetting of wettability index,the index of USBM wetting fitting method characterized by mathematical calculation for the wetting Angle theta,facilitate the wettability were introduced to the reservoir engineering calculation;The use of surfactants on the reversal caused by capillary pressure curve direction of low interfacial tension at the end of the capillary pressure curve becomes very low,capillary resistance into power,beneficial to the improvement of the reservoir development effect.5.For the measured oil-water relative permeability curves are normalized,regression of the analytical expression of the relative permeability curve this paper puts forward the modified capillary pore throat ratio for the concept of Ncc,the experiment established the relationship between Ncc and Sor chart,calculate the relative permeability curve chemical flooding,comparing the measured chemical flooding curve of relative permeability curve,the calculation method for accurate,can be used in the chemical flooding reservoir numerical simulation calculation.6.Through chemical flooding method to calculate the relative permeability curve of oil displacement efficiency,ultimate oil displacement efficiency,injection capacity,relative injection capacity was calculated;And damage to reservoir stress sensitivity of permeability damage after the change of relative permeability curve of computing research.