Study Of Production Decline Law & Water Flooding Behavior In

Fractures were easy to increase the complexity of the progress of oil-water Seepage Flow in reservoir. As a result, it is hard to study the percolation features when the oil was flooded by water in low permeability formation, which always develops fractures. On the basis of Quasi-linear Seepage Flow theory, the formulas of theoretic relative permeability curve, which have had considered fracture development in low permeability reservoir, have been deducted in this paper. The parameters a and b, included in the formulas, were comprehensive characterization of fractures, permeability, pore size distribution, fluid viscosity, interfacial tension, wettability and so on. The theoretic relative permeability curve was able to reflect the oil-water percolation features through the whole development of low permeability reservoir, which was significant for theoretical research. Below was an examlpe about the study of production decline law in low permeability reservoir. The oil phase relative permeability curve presented a change from a linear relationship to an exponential relationship with the increase of the water saturation, which meant an exponential decrease and a harmonic decline of the single well production. This rule was used to fit the historic production dynamic and to predict that of future. The fitting acuracy was high enough to meet the production demand, which proved that the rule obtained above was able to pridict the production dynamic of a singal well in a short pea of time in the future.The study of waterflooding behavior, which was reflected by water drive curve, was significant for the development of low permeability reservoir. There existed one to one correspondence between a specific reservoir and a specific kind of water drive curve. For a specific reservoir, selecting the most suitable water drive curve was the key. The curves of relationship between Np and fw, correspondence to the four main water drive curves, were compared with the curve plotted with the data from production practise in this paper. Judging from the fitting extent,the Hepatitis C curve was considered as the most suitable one for low permeability formation in WY Block. Then the Hepatitis C curve was used to predict the water cut increasing situation with the recovery degree, as well as the recoverable reserves.The curve of water cut increasing showed that most of the recoverable reserves was recovered in the middle and high water-bearing period, which has had been proved by the relative permeability curve of low permeability formation in WY Block. The decreasing rate of oil phase relative permeability curve got smaller and smaller in high water-bearing period, when the water cut was greater than seventy percent. At the same time, the high water-bearing period occupied almost half of the whole development period. As a result, the monitoring of production dynamic, as well as the production management, should be emphasized especially in high water-bearing period, which would be benefical to receive a stable yield per year for a long pea, as well as a higher oil recovery and better economic.