Two Phase Relative Permeabilities Using the Ultracentrifuge

ABSTRACT

Two phase immiscible displacements in the ultracentrifuge were used for the determination of the relative permeability characteristics of a variety of systems including Berea sandstone, Baker dolomite and plugs from the Rainbow Keg River Reefs. The transient production data for each plug were collected and were used for the estimation of the relative permeabilities. A computer simulation algorithm was developed for this purpose. The program uses explicit history matching of the production data by fitting them using Corey type exponents for the relative permeability. Both oil flood and water flood data were utilized. The paper describes the experimental procedure, the development of the model and representative experimental results. In general, the proposed algorithm better fits the tighter carbonate samples rather than the data from the more permeable samples. The simulation seems to be very sensitive to the capillary pressure data.

Introduction

Research on relative permeability measurements has been the document research topic in petroleum engineering for the past fifty year. Numerous papers and reports have been published. This paper deals with the combination of relative permeability and centrifuge techniques. Starting from the original paper of Hasster and Brunner (1) much effort has been spent both on the experimental part and the interpretation part of centrifuge technology.

The use o the centrifuge for relative permeability measurements probably starts with the paper by Hagnort (2) where in was shown that the centrifuge can be utilized very efficiently for the laboratory evalution of gravity drainage. Hogoort identified the relative permeability to oil as the key factor for the observed very high recovery associated with gravity drainage. He developed a centrifuge technique for the measurements of oil relative permeability In his analysis, he used dimensionless numbers such as the capillary number, the Bond number and the gravity number and identified regimes for different types of flow.

Applications of centrifuge technology for the measurement of two and three phase relative permeabilities are given by Van Spronsen. Assuming that the three phase capillary behaviour is not substantially different than the two phase. he extended the algorithms of Hagoort (4) for both water and oil in a three phase system. He suggested using fluids of high viscosities to compensate for the effect of the change of the rotational speed in the initial phases of drainage tests. He performed tests on core and fluids from the Weeks Island project and found that the incremental recovery due lo tertiary CO 2 injection is very sensitive to the shape of the three phase oil isoperms. The shape of isoperms is found by taking a ccnain value of the oil for water) relative permeabilities and finding the corresponding oil and water saturation for each experiment in each sampple and plotting these data in the ternary diagram for each isoperm value considered. However, the use of data points from several samples can lead in a large scatter of these data points.

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