| LQ3-1 field is located in Liaodong Bay of Bohai,in order to improve oil recovery within the oil production platform life span as far as possible,oil field uses a combination of water injection and flooding manner mining.However,to achieve the effect of increasing oil precipitation,the well of the benefit from weak gel flooding began to back out of the polymer.With the increase in the proportion of polymer-contained sewage,the quality of oil field injection water worsened gradually.The injection Wells are generally appeared high pressure,acidizing poor results,injecting insufficient clearly.Reservoir absorption capacity began to decline.So it is necessary to do a systematic research for the mechanism of damage and technology in the polymer containing sewage recycling,for the sake of providing a favorable guarantee for sustainable and efficient development of oil fields.The main reservoir of LQ3-1 oilfield is the second member of dongying formation,belonging to deltaic sediments.In this paper,the characteristics of physical property,lithology,pore structure in the E3d2 will be studied by means of the casting thin sections,mercury injection,scanning electron microscope(SEM),x-ray diffraction and other modern means of testing.Studies have shown that the physical property of the major reservoir is better,belonging to high porosity medium permeability?high porosity high permeability.But because of the strong heterogeneity,it's easy to have a interlayer interference problem by means of general water injection.The casting thin sections show that the lithology of E3d2u is mainly coarse-grain feldspar debris sandstone,the lithology of E3d21 is mainly packsand and siltstone feldspar lithic sandstone.Rock of reservoir is loose cementation,intergranular pores development,higher clay minerals which dominated montmorillonite content.So in water-flooding oilfield has potential speed sensitivity and water sensitivity damage.Water quality survey results show that the oil content,suspended solids content,SRB and other major water indicators exceeds bid badly.Suspension solids components is given priority to with organic matter,followed by corrosion products.Back out of the polymer increases the difficulty of sewage disposal is a major cause of the current water quality exceeds bid.Therefore it is proposed to increase the polymer processing equipment,at the same time,add effective chemical treatment agent to facilitate of sewage treatment.The sewage which have low concentration of polymer damage to the reservoir weaker by experiment of static compatibility and reservoir adaptability.But the existence of polymers have a huge impact on the growth of calcium carbonate rule.Observing the scale sample with polarizing microscope and scanning electron microscopy shows that when it contains polymer,the scale and size by excluding of the 50 microns dropped to under five microns.Small particles of 5?m often aggregation grow,the phenomenon with the polymer concentration,the higher the more obvious.Simultaneously,calcium carbonate particles were often polymer package.Combined injection wells dynamic data analysis that water quality exceeds bid is the main cause of water injection difficulty.At the same time,excessive injection intensity and not compatibility between injection water formation water are also the important reason for the water injection difficulty.Which should improve the quality of injection water quality,control injection strength and increase the anticrustator to improve the state of water injection difficulty.When water contains polymer,the size of the particles appears to coexist phenomenon,and causes reservoir proximal and distal double blockage,increases acidification difficulty.And calcium carbonate wrapped by polymer is suppressed acid react therewith,thereby reducing the acidification effect.Therefore recommended that carry on organic plugging removal before acidification,while strictly controlling the content of the polymer in the injection water. |
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