Oil Saturation Measurements in the Bartlesville Sand After Waterflooding And After Propane Flooding
Authors: Holm L.W. 
Published: December 2007

In this post-waterflood test, oil saturations determined from logs agreed well with those from production tests using laboratory-measured relative permeability data. Information was obtained on oil saturations before and permeability data. Information was obtained on oil saturations before and after propane flooding, on the distribution of propane in the sand, and on the flow of oil mobilized by the propane during the flood.

Introduction

The Delaware District Unit, located in Nowata County, Okla., and covering about 2,500 acres, was discovered in 1910. The reservoir rock and oil characteristics are summarized on Table 1. The production from the Bartlesville sand was by both primary and secondary methods. The secondary methods included pumping under vacuum, air and gas injection, and waterflooding. Since the waterflood was approaching its economic limit (Fig. 1) and since a material balance indicated that the oil saturation remaining in the reservoir was about 43 percent PV, it was decided to conduct a pilot test to determine whether additional oil could be economically recovered from the watered-out area in this reservoir. Because of the shallow depth and low pressure of the reservoir, a miscible flood could not be achieved. A laboratory investigation of the immiscible propane slug displacement mechanism, indicated that injection of a 4-percent PV slug of propane, followed by air and then water, could recover substantial amounts of oil from watered-out areas. It was also found in laboratory work that a more effective technique was reverse flooding; i.e., propane is injected, then air and water are injected into the existing production wells and the existing injection wells are converted to producers. Laboratory studies showed that, with small slugs of propane, higher and more efficient oil recovery was obtained when the propane was injected into an area where mobile oil saturation was present. A field test of this reverse flow. propane flood was conducted and is described briefly in Appendix A. To determine more accurately what had occurred in the reservoir during the flood, three wells were drilled into the Bartlesville sand on a line between an injection and a production well. Oil saturations were determined at these well locations from the following sources of information:

1. Conventional core analyses.

2. Special logging procedures.

3. Production history of these core wells and therelative permeability data obtained on the cores.

The oil saturation values determined from the above sources of data were compared with those measured in cores taken when the injection and production wells were originally drilled. The values production wells were originally drilled. The values were also compared with calculations of oil saturation based upon the Buckley-Leverett fractional flow formula using production data from these wells. The results of the oil saturation measurements are presented in this paper. presented in this paper. Procedure Procedure Wells Drilled in Pilot Area

Three wells (W. L. Connelly Nos. 1, 2. and 3) were drilled in the propane test area during 1962 and 1963, as shown in Fig. 2. The wells were cored and logged, and Nos. 1 and 3 were completed as producers.

JPT

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