A significant expansion has occurred in North Dakota to accommodate disposal of produced water since the onset of oil production from the Bakken petroleum system. Anywhere from 1-2 barrels of water are associated with each barrel of oil produced in the Williston Basin. The growth over the past 10 years warrants a closer examination of the reservoir in which we store produced water and the related injection well performance. A sample of well test data, and an investigation of average injection pressure, cumulative injection, and injectivity index suggest that poor injection performance is associated with limitations to reservoir quality. Historically good injection wells appear to maintain positive injection volumes and are not significantly limited by wells added nearby. Increases in reservoir pressure are evident over limited geographic areas. Wells in these areas tend to suffer lower injection rates, and higher average injection pressures. The evidence from well testing, current geologic investigations, and geographic well characteristics suggest that localized geologic properties and reservoir quality are the primary limiting factors for poor injectivity performance.

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