This paper presents an innovative completion technology, fine tuned by reservoir simulations, for balancing the water injection profile into various sand formation zones in an open-hole completed injector well, increasing sweep efficiency.
Traditional injection wells often suffer from the risk of sanding in, hence sand control is beneficial or even required. Another major challenge is to achieve even distribution of the injected water into all zones along the well-bore. Injector wells are often designed to penetrate, and give pressure support to, several reservoir intervals with various permeabilities which challenges the reservoir management. Permeability contrasts, heel-toe effect, formation damage, creation of thief fractures and well bore injectivity changes need to be managed to avoid early breakthrough in adjacent production wells. Smart-well systems are highly complex and costly, and for this particular case, where raw seawater is used, the high corrosion resistance requirement was considered a show stopper.
The solution was to qualify and install special screens with integrated flow control devices, tailor-made for injection wells, and with correct nozzle sizes for this particular case. These screens were made of materials selected to withstand the corrosive environment and high rate of unfiltered water during lifetime of the well. The screens where gravel-packed to restrict annular flow and give zonal isolation, which optimizes regulation of reservoir heterogeneities.
This new technology is representing a quantum leap forward in field economics, by marrying all the benefits realized with this simple robust and reliable self-regulating injection management system.
The paper will discuss the qualification program inclusive focus on risk of erosion, plugging and corrosion. Further, the completion design of the well, with flow distribution simulations and sensitivities inclusive comparisons with actual field date is also reviewed together with economic value analysis. Future potential, applications and scenarios will also be discussed.
Introduction
Urd was developed as a satellite to Norne FPSO during 2004–2005. The oil field consists of two separate structures, Svale and Stær, located 4 and 9 km from the main field. The field was put on production in 2005 and was developed with 3 subsea templates, and pipelines for oil production, water injection and gas lift (Figure 1). Norne and Urd is operated by Statoil on behalf of ENI Norge AS Norsk Hydro Production AS and Petoro AS.
The application of the special screens with integrated flow control devices for injection wells (called ICD injector) was evaluated as a part of the field development plan for Urd. Since both Svale and Stær consist of heterogeneous pay zone, the main reservoir management goals of implementing an ICD injector are:
The important feature of the ICD injector is the self-regulating effect with functions independently of surface control. If one zone is fractured during the operation of the injector and can take more water, then the nozzle in the ICD injector will prevent increased injection into this fracture. This will ensure improved water distribution, which will result in better pressure support and drainage of the oil reserves in all zones.
