Redefining fluids relative permeability for reservoir sands. (Osland oil and gas field, offshore Niger Delta, Nigeria)

摘要

Redefining oil and water relative permeability for the evaluation of reservoir sands, a case study of Osland oil and gas field, Offshore Niger Delta, Nigeria has been carried out. The aim of this study is to modify water relative permeability (K-wr) and oil relative permeability (K-or) equations in sandstone units. The objectives are to provide alternative expressions for K-wr and K-or in sandstone units, use the equations as inputs in a simplified water cut (C-w) equation to predict the volume of water that will be associated with the recoverable volume of oil (V-Ro) in penetrated reservoirs. The relationship between porosity (Phi) and water saturation (S-w), with the relationship between porosity and hydrocarbon saturation (S-h), were used to evaluate K-wr and K-or in order to predict C-w in the selected reservoirs. Reservoir X in Well D-1 shows about 2.0 x 10(6) bbl for V-Ro and 18.78% for C-w but in D-2 it shows about 7.4 x 10(6) bbl and 1.73% for V-Ro and C-w respectively. Similarly, in Reservoir Y, D-1 has about 6.8 x 10(6) bbl of V-Ro and 0.034% of C-w, but in D-2 it has about 9.3 x 10(6) bbl of V-Ro and 0.015% of C-w. The results suggest that high (I) with corresponding high S w resulted in high associated C-w in Reservoir X. The evaluation also confirmed that the decrease in the ratio of oil relative permeability to water relative permeability (K-or/K-wr) corresponds to the increase in C-w. The total recoverable volumes of hydrocarbons from the two wells are estimated at 7.7 x 10(9) cu.ft for gas and at 2.54 x 10(7) bbl for oil. With the present conditions of the two reservoirs, the values of C-w in Reservoir X are low and are extremely low and negligible in Reservoir Y. Reservoir X in Well D-1 has a smaller volume of V-Ro but the C-w is higher than others. Nonetheless, the C-w in Reservoir X is still within acceptable range. (C) 2017 Elsevier Ltd. All rights reserved.