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Abstract

The Jennifer (Queen) Unit produces from a northeast extension of the Concho Bluff, North Field of Ector County, Texas within a Queen producing trend containing four separate reservoirs. The three adjacent reservoirs have been successful waterflood projects due to very favorable rock and fluid properties The Jennifer (Queen) Unit reservoir was an obvious candidate for waterflooding shortly after discovery in 1984 as its areal extent became apparent. Extensive data gathering enabled reservoir modeling to assess the efficiency of a waterflood project. When installed, the Project raised production from 120 BOPD to 2500 BOPD in 5 months. Intense waterflood surveillance has identified operational problems at an early stage and provided data for an updated reservoir model. The enhanced simulation will help manage the flood for optimum recovery.

Introduction

The Jennifer Queen Unit's reservoir was discovered in August 1984 with the completion of the Rendova-Jennifer #1 that potentialed on pump for 95 BOPD and 4 BWPD potentialed on pump for 95 BOPD and 4 BWPD with gas TSTM. The reservoir had been penetrated by earlier wells, but the penetrated by earlier wells, but the productive nature of the Queen interval was productive nature of the Queen interval was not recognized probably due to severe formation damage. Although the wells in what is now the Jennifer Queen Unit were placed in the Concho Bluff, North Field, placed in the Concho Bluff, North Field, they produce from a separate reservoir within a Queen producing trend containing three other reservoirs. This trend is located at the confluence of crane, Ector, Midland and Upton Counties on the eastern shelf margin of the Central Basin Platform (Figure 1).

The other three reservoirs in the trend, two of which are direct offsets, have been successful waterflood projects. it was obvious that, as the field developed, the Jennifer Queen Unit reservoir was a waterflood candidate. Shortly after discovery, Rendova initiated data gathering activities including coring and quantitative logging to facilitate a waterflood study. in addition, well completions were designed with a future waterflood in mind. Unfortunately, the bulk of the reservoir was under two leases which contained onerous terms as to drilling obligations required to earn acreage. Consequently, development of the reservoir proceeded with uneven well spacing.

The lack of gas in solution and the subsequent rapid decrease in bottom hole pressure was an additional incentive for pressure was an additional incentive for the working interest owners to install a waterflood at an early date. Even though the typical well encountered a relatively thick, permeable pay section with initial capacity in excess of 100 BOPD, rapid depletion occurred. The quality and continuity of the pay sections, the relatively low viscosity of the oil and the lack of primary reservoir energy assured that the reservoir would respond quickly to water injection regardless of the scheme utilized. The offset reservoirs' waterflood performance was proof of this.

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