Study Of Gas Injection Development Effectiveness Of Fang Forty-eight Pilot Area

With the super-speed development of national economy, the demand of oil is more increasing, but the major oilfields in the east of our country have been in the high water-cut period, and the production of oil is dropping. Since the 90s, the reserves of the low permeability oilfields have been increasing quickly, and it keeps the larger and larger proportion in the total proved reserves. In the past few years, the proportion of the reserves of the low permeability zones have been up to 60%~70% of the proved reserves of that year. It expresses that the low permeability zones will be the main resources foundation of increasing reserves and ascending production in a long period of the future, and the using and development of the reserves of the low permeability oilfields have been one of important potentials of stable development of petroleum industry of our country. The development of the low permeability oilfields is more difficult than that of the high and middle permeability oilfields, and the problems of the development of the low permeability oilfields are too many, so it is necessary to pay more attention to performance the analysis research of exploitation mechanism of the low permeability zones and the pass experiments of process technique. Fang forty-eight pilot area is a typical low permeability oilfield, and the main factors that affect the development result of Fang forty-eight pilot area are the permeability and starting pressure gradient. Trough the experiment study of the pseudo-starting pressure, oil-water relative permeability, gas-oil relative permeability and enhanced oil recovery of the low permeability, the paper draws the conclusion that the rock in the test area exists the pseudo-starting pressure, which is one of important reasons to decide the recovery scheme. Because of the low permeability oilfield, the saturation to use is low. When the oilfield exists water breakthrough, the drop of the oil production index is very quickly, and the rise of the liquid production index is very slowly, so only raising the liquid production ability is difficult for the development of the low permeability oilfield to attain the purpose of steady production. Although the efficiency of gas drive is better than water drive, and the residual saturation of gas drive is lower than that of water drive, the gas-water relative permeability could not rise. It can enhance oil recovery to performance water-gas alternation drive, but carbon dioxide drive and natural gas drive are better than nitrogen drive in different air.