Study On Bottom Water Flooding Recovery Rate Of Fractured Gas Reservoirs With Different Penetration Degrees

KS gas reservoir belongs to low porosity and low permeability of cracks pore edge-bottom water dry gas sandstone gas reservoir, well test and production have proved the presence of cracks, cracks development degree is well. The facture dip angle is large, mostly high angle seam, so master the law of gas reservoir water invasion is of great significance for efficient development of gas reservoir. The current research of cracks seepage are mostly glass model, there are few researches of reservoir core under different crack penetration level of bottom water flooding. The seepage research for core with cracks is not yet mature. It is unable to better describe the complex flow gas water process, so the establishment of physical simulation study of crack law of development of gas reservoir water invasion and water invasion mechanism has important significance. This paper is based on the project "exploration and development of science and technology condition platform experiment new technology research", through the physical experiment and numerical model, to study the water invasion regularity of different proportion of crack and the influence factors of recovery efficiency.At first, this research used the reservoir cores produced core model with different crack ratio to study the influence of displacement pressure and crack ratio on water flooding efficiency.6 groups of different crack ratio core model of water drive gas experiment were completed. Then, different crack ratio of reservoir numerical model with a total of 61 sub models was set up. It is in order to study the influence of the crack of high permeability zone, crack permeability ratio and penetrating forms, quantity, distribution and volume ratio of water and the well proration and other factors on gas well production and recovery efficiency. The consistent with the experimental results is obtained.The results show that:(1) In the water drive gas experiments, when the crack ratio value is the same, the greater the displacement pressure, the higher water drive efficiency; when the displacement pressure is the same, the greater the crack ratio value, the lower water drive efficiency. (2) The lower the water ratio, the greater the gas recovery factor. Single well proration production is bigger, the recovery of a gas well corresponding also is higher, but overall. (3) The number and distribution and permeability of high permeability zone, are all the influence factors of gas well recovery factor. But the most important of these is the distribution of high permeability zone, only when the distribution of high permeability zone is beneficial to increase fluid seepage ability between the reservoir and the bottom hole, can the recovery of a gas well be greatly increased. (4) The crack of high permeability zone from bottom to top through degree is higher, the higher the gas recovery, but not all throughout, recovery efficiency is very low, the recovery efficiency are within 14%. (5) The crack of high permeability zone with the gas well connected opens the reservoir from top to bottom, gas well recovery factor increases quickly, compared with the same proportion bottom-up way through reservoir. When the high permeability zone is completely through reservoir, water invasion phenomenon is serious, there will be a sharp drop in gas well recovery factor. So when develop this kind of gas reservoir, we must carry on the fracturing operation in the process of reservoir development, but should prevent reservoir was completely through.