NONLINEAR REGULARITIES OF INDICATOR CURVES TAKING INTO ACCOUNT RESERVOIR DAMAGE EFFECT
M.I. Epov1, N.N. Mikhailov2,3,4, V.N. Sokotuschenko2, O.M. Ermilov2,5
1Trofimuk Institute of Petroleum Geology and Geophysics, Siberian Branch of the Russian Academy of Sciences, Novosibirsk,Russia
2Gubkin Russian State University of Oil and Gas, Moscow, Russia
3Institute of Oil and Gas Problems, Russian Academy of Sciences, Moscow, Russia
4M. V. Lomonosov Moscow State University, Moscow, Russia
5LLC “Gazprom Dobycha Nadym”, Nadym, Russia
Keywords: hard-to-recover reserves, low-permeability reservoirs, nonlinear filtration, well flow rate, drawdown pressure, skin factor, formation damage, indicator curves, hysteresis, power-law filtration.
Abstract
Concerning low-permeability reservoirs with hard-to-recover (HTR) hydrocarbon reserves, we comprehensively analyzed the influence of nonlinear reservoir processes on well flow rate–drawdown pressure relationship.
We identified new nonlinear relationships between the flow rate of low-permeability reservoirs and reservoir drawdown (indicator curves). The nonlinearity of the indicator curves is due to the combined effects of nonlinear filtration, technogenic reservoir change, and the dependence of formation damage parameters on drawdown. The applied approach allowed us to find out qualitatively new regularities in the relationship between flow rate and drawdown in low-permeability reservoirs. A well productivity analysis revealed hysteresis in the indicator curves and a shift in critical drawdown values when considering both formation damage and filtration nonlinearity. It was established that the combined effects of nonlinear filtration and damage effects lead to an additional flow rate reduction of 25–40% compared to separately considering each of these effects. The obtained results are of practical significance for optimizing the development of low-permeability reservoirs with HTR reserves and for predicting their productivity.
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