Chang 3 reservoir in Hua 152 block is located in the Ordosbasin, China. The average permeability and porosity is3.17mD and 14.9%. There exists serious scaling at the oillayer near to bottom hole because of high salinity formationwater and incompatible injection water. The scaling processand mechanisms in the layers has been researched by means ofa visual real-sand micro-model. The results have shown that:1) The permeability of the oil layer will reduce by 40% whenformation water contacts with injection water twice times atthe same place; 2) It is very easy for scaling molecules tocrystallize from water phase and scale particles are very smallbecause the pores and throats of the formation rock contain alot of fine clay and impurity; 3) The scale accumulates inpores and looks like “chicken roost”; 4) The scale inhibitorscan reduce scaling, but the higher concentration of scaleinhibitors is needed. Scaling in low permeability reservoirsmay significantly reduce rock permeability thus affecting theproduction of oil well. The visual real- sand micro-model is agood method to use in research of scaling mechanismsbecause of its visualization, using actual rock and ease ofconstruction.
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