Experimental justification of technique for core-derived gas recovery factor of reservoir formations

Abstract

This article is devoted to approbation of a technique for core-derived gas recovery factor in a production laboratory in connection with its upcoming standardization at SOU level. It briefly describes the technique, which is based on obtaining water and core saturation reduction curves when centrifuging samples followed by graphic-analytical processing of these curves. On the example of determining core-derived gas recovery factor of the Horizon C-5 of Berezovske field we identified possible sources of errors and provided recommendations on their elimination by introducing some changes to a method of adding kerosene to saturate the samples with respect to the method adopted in GOST 26450.1-85. The purpose of these changes is to minimize the loss of residual water saturation due to evaporation under vacuum treatment. The essence of the changes is that the samples with residual water saturation are resaturated with kerosene pre-vacuumed separately from the samples and that the vacuum is supplied to the samples with residual water only briefly, for capillary impregnation time, for its stimulation. After introduction of these changes the technique for core-derived gas recovery factor can be considered as approved and it may be recommended for standardization.