A New Design for Advanced Well Completions

Abstract

Abstract Advanced well completions (AWC) have shown great benefits not only with respect to production optimization, but also data collection were they provide very useful PLT type information on a zonal basis (ref. 1, 2, 3). However, as many of the wells with advanced completions have matured and more data been acquired over longer production periods, some a better understanding of the production behaviour has been gained. Installing an inner tubing with associated flow control valves in a horizontal liner causes restrictions to the flow, and an increased pressure drop. One the StatoilHydro operated Visund field, one has observed that at certain well conditions (related to combinations of rate, water cut (WC) and gas oil rate (GOR) this pressure drop leads to a noticeable reduced well potential, and thereby a reduced overall robustness of the well design. By increasing the production liner diameter in the reservoir section, one may be able to install advanced completion equipment with bigger dimensions. This allows the benefits of the downhole zonal control to be realised without hindering the well potential. Data from two wells one the Visund field, has been used to demonstrate the benefits related to increasing the diameter of the production liner, and consequently the dimensions of the advanced completion components. A hydraulic well model has been constructed comprising one producer and one gas injector. When the models are matched to actual rates (and well conditions), the effect of varying the flowing diameter (= inner tubing diameter) is studied. The results show that there is an upside with regards to flexibility and well potential with such an optimized completion design. In relation to the model findings, the consequences for the drilling and completion design and processes are outlined. Advanced well completions The term Advanced well completion is a system that includes permanent instrumentation (more than one pressure and temperature gauges) in combination with inflow control devices. In addition further instrumentation may be installed, for example a down hole flowmeter. Such completions give the possibility to control inflow on a zonal basis within the different reservoir layers. See Figure 1for a typical completion design Wells with advanced completion came into general use in the beginning of the 1990's. StatoilHydro installed its first such completion in 1997, and by march 2009 115wells with remote operated Inflow Control Valves (ICV) have been installed in more than twenty StatoilHydro operated fields. Even if an advanced completion leads to increased cost, the well planning process in StatoilHydro has identified great benefits with regards to improved economy with such completions, both on increased recovery, but also on reduced intervention work, as optimal production from different reservoir zones otherwise may only be obtained with sequential production (and several well interventions).