Page 196 - Gas Wettability of Reservoir Rock Surfaces with Porous Media
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180     Gas Wettability of Reservoir Rock Surfaces with Porous Media



                            tubes. The two are perpendicular with 72 nodes in total. There are guiding
                            grooves vertically and horizontally at the two ends of the model, which aid in
                            injecting fluids evenly. The diameter of the thicker capillary channel in the
                            center of the model is 0.2 mm, and the diameter of pores is 0.92 mm. The
                            diameter of the capillary channel with symmetrical structure on two sides is
                            0.12 mm, and the diameter of pores is 0.5 mm. Except the guiding groove, the
                                                                       2
                            pore-throat area of the entire model is 32.36 mm .
                            5.2.1.2.2   Wettability Treatment of the Micromodel
                            The air in the micromodel was pumped off using a vacuum pump and satu-
                            rated with the fluorocarbon polymer gas-wetting alteration agent solution of
                            different concentrations. It was then put aside for 24 hours. The solution was
                            displaced by high-pressure air, before it was placed and dried in an oven at

                            80 C.
                            5.2.1.2.3   Measuring Wettability of the Micromodel
                            As the micromodel is a porous network media, gas wettability of pore-throat
                            surface of the etched glass model treated with gas-wetting alteration agent
                            solution of a certain concentration is characteristic of gas wettability of the
                            inner wall of the capillary, treated with solution of same concentration.

                            5.2.1.2.4   Displacement Experiment of Micromodel
                            First, the model was saturated with air before distilled water or neutral kero-
                            sene was slowly injected in the model at a speed of 0.3 mL/h with a peristaltic
                            pump, for water or oil displacing gas experiments. The distilled water was
                            dyed with methylene blue, and the neutral kerosene was dyed with Sudan red.
                            A microscope camera is attached through an optical microscope to study the
                            percolation characteristics of gas/water or gas/oil system in the model and dis-
                            tribution after displacement.

                            5.2.2   Gas Wettability of Gas/Water System With Etched
                            Glass Network Model
                            The study of microscope percolation mechanism of the two phases (gas/water)
                            in porous media is the theoretical foundation for developing water-displacing
                            reservoirs. Wettability is an important aspect of the physical property of the
                            porous media surface. It has a significant effect on microscopic percolation
                            mechanism of the two phases (gas/water) in porous media. However, at pres-
                            ent the microscopic percolation mechanism of the two phases (gas/water) is
                            primarily specific to developing oil reservoir. Studies on microscopic percola-
                            tion mechanism of water-displacing gas reservoirs are few, and the microscopic
                            percolation mechanism of the two phases (gas/water) study the porous struc-
                            ture and the effect of input speed on the percolation mechanism of the two
                            phases (gas/water) [6 8]. Therefore, the wettability of porous media is signifi-
                            cant in the study of the microscopic percolation mechanism of the two phases
                            (gas/water).
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