The Feasibility Of Converting An Existing Waterflood To A Polymer Flood: A Case History Of West Yellow Creek
Authors: Strickland Paul H. , Wilson Jeffrey T. , Warnock William E. 
Published: December 2007

Oil recovery may be significantly increased by the introduction of polymer chemicals into the injection water of many existing waterfloods. However, a basic understanding of the effects of polymer injection (on both the surface equipment used for injection and the reservoir) is required to properly design and evaluate the polymer flood process. This paper presents the major aspects associated with presents the major aspects associated with converting the waterflood project at West Yellow Creek Field to a polymer injection project, and outlines operational experience project, and outlines operational experience gained to date.

Introduction

Considerable industry time and money has been invested in laboratory analysis of polymer solutions and their applicability to waterflood projects at reservoir conditions. However, projects at reservoir conditions. However, in the area of field application of polymer flooding, industry data are particularly lacking. In a field application conditions encountered at the surface can significantly impact the overall flood design and economics, and therefore must be included in the original project justification. Several challenges project justification. Several challenges were encountered pertaining to surface control of the polymer solution at West Yellow Creek.

RESERVOIR DESCRIPTION AND FIELD HISTORY

The West Yellow Creek Field is located in Wayne County, Mississippi, and was discovered in December, 1947. The majority of production in the field is from the Eutaw Oil Pool on the southwest side of a deep seated salt dome. Splinter faulting divides the productive interval into five fault blocks, with one fault block containing 92% of the total productive volume. The Eutaw Pool consists productive volume. The Eutaw Pool consists of four separate continuous stringers which are referred to as the Morrison, City Bank 1, City Bank 2 and Stanley sands. A structure map on the top of the Eutaw Pool and a typical well log are shown in Figure 1. Reservoir characteristics for the Morrison, City Bank 1 and City Bank 2 sands (collectively called the floodable zones) are shown in Table 1.

Primary production in the West Yellow Creek Primary production in the West Yellow Creek Field was competitive with several producers operating within the field. Most operators produced all four stringers simultaneously, produced all four stringers simultaneously, so that accurately accounting for primary production between zones is difficult. production between zones is difficult. However, where commingled production was not occurring, the Morrison, City Bank 1 and City Bank 2 stringers appeared to exhibit no significant natural water-drive mechanism. The Stanley stringer, however, is quite thick with pressure support from a moderate waterdrive mechanism. Primary production had reduced the average reservoir pressure of the floodable zones to 300 psi and the Stanley sand to 500 psi when the Eutaw Pool was unitized for secondary recovery purposes in October, 1971. Water injection was initiated in February, 1973, after an extensive workover program was completed to segregate Stanley program was completed to segregate Stanley sand production from the floodable zones production. A non-repeating injection pattern production. A non-repeating injection pattern was established with 21 injection wells utilizing downhole flow regulators to inject into each stringer individually.