Abstract

In the current and future scenario of increasing demand for hydrocarbons, Multi-Disciplinary Integrated Waterflood Management team is the key to achieve ultimate recovery. In Raudhatain Upper Burgan reservoir production started in 1959 with initial reservoir pressure of 3850 psi. Decline in reservoir pressure with sustained rate of production indicated weak aquifer support and initiated water injection during the year 2001. With four major flow units, poor sweep efficiency often results from spatial variation and/or heterogeneity in the permeability of the reservoir rock, usually resulting in an irregular displacement front of the injected fluid. The initial completion design did not address the injection profile control. The integrated waterflood management team initiated number of projects to increase the productivity like Water Flow Regulator technology (WFR). The objective of using this technology is flooding all the units so as to improve the overall sweep efficiency.

To optimize vertical & areal sweep efficiency and enhance production from the uncontacted portions of this reservoir, a paradigm shift in water flood strategy was adopted for selective injection strings using WFR. These devices enable to control injection rates in specific layers with different reservoir pressure, permeability, skin damage or any other factors that would normally affect flow. The new completion design with WFR was installed in one of the water injector wells, thereby recompleting the well, switching from the conventional to the straddled packer completion, grouping four flow units into 3 zones with WFR, rationalizing the splits as per needs per layer vis-a-vis to the perforations in nearby producers.

This novel technology was successfully applied in three Raudhatain upper Burgan wells. The results are very encouraging, vertical injection profile vastly improved by enabling higher injection rates into layers that never received water. Before commissioning of water flow regulator, most of the injected water was traversing through the high permeable zone only. The vertical water injection profile due to WFR approach resulted in choking the flow through high permeable layer and improved the flow in the remaining uncontacted layers. Production logging was conducted before and after commissioning of WFR to confirm the results. In the long term, this approach is likely to add production, reserves and ultimate recovery factor.

The first implementation of WFR in North Kuwait Field, has proved the concept of improving vertical injection profile. Based on comprehensive evaluation, a campaign of completing 9 more vertical injector wells with this selective-string design is planned by KOC. The re-engineering of injection profile has paved the way for application of this technique in other similar reservoirs of Kuwait.

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