Study Of The Flow Of Shale Gas In Micro/Nano Pore Medium By Direct Simulation Monte Carlo

In the research of the flow of shale gas in one dimension by DSMC, the results show thatthe normalized flux decreases in slip flow regime as Kn increases, while the trend reverses infree molecular flow regime. Thus the minimum value occurs in transition regime which isbetween slip flow regime and free molecule flow regime. The distribution of stream speedperpendicular to stream in the pore throat tends to be smoother as Kn increases and there is noobvious change when Kn gets into free molecule flow regime. With Kn rising, the centerlinevelocity, first goes down rapidly in slip flow regime, and then climbs up in free molecule flowregime, but the slip speed increases uninterruptedly until it approaches centerline velocity.The shale gas flow in two-dimension micro/nano pore throats was simulated by DSMCto obtain its physical properties. As average pressure or pore diameter increases, the centralpart of pressure distribution of shale gas along the pore throat becomes high slightly, but thewhole profile holds similar trend. So does the speed distribution along the pore, which risesoverall as Kn increases, but the linear relationship did not appear because of the effect ofaverage pressure in Klinkenberg effect. The slip speed does not present visible change. Andthe results from simulation show that it leads to same influence that pore diameter andaverage pressure multiply respectively. The effective permeability of pores with the diameterof10nm,20nm,50nm,100nm,500nm increases as the decrease of pore diameter or theincrease of average pressure. The linear relationships exist approximately between effectivepermeability and the reciprocal of average pressure. But the value of b in Klinkenberg effectwas not same for different pore diameter. The reason is that the influence of wall on shale gasflow in micro/nano pore can not be neglected in transition regime.Here the shale gas flow in pores with different diameter by DSMC was simulated to getthe distribution of pressure and velocity in centerline. The pressure along the pore dropssharply in the location of orifice, which shows that the orifice can decrease the pressure, and the velocity distribution grows up there. With the rising of average pressure or pore diameter,the distribution of pressure and velocity along the pore holds the similar trend with that ofstraight pore. The effect permeability of pore with different diameter reveals that the trend issimilar with that of straight pore, yet the value is larger.