Downsizing, Use of Dummy and Venturi Valves Enhance Gas Lift Performance

Abstract

_ This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 213975, “Gas Lift Performance Enhancement Strategies by Downsizing and Using Dummy and Venturi Valves: A Paradigm Shift in Gas Lift Systems Management Philosophy,” by Wael F. Akeil, Ahmed M. El-Bohoty, and El-Sayed I. Abd El-Mawla, Gulf of Suez Petroleum Company, et al. The paper has not been peer reviewed. _ A mature offshore Egyptian field has entered a depletion phase. Most of its gas lift design bases were initiated during production startup and feature standardized sets of large gas lift valve port sizes with narrow spacing. Inconsistent well flow during reservoir depletion adds complications to the system. Therefore, a screenout model was created to select candidate wells for downsizing and for changing out with dummy and Venturi valves. After screening, 70 wells were selected for application of the new strategy. The complete paper discusses the effectiveness of smaller port sizes and the use of dummy and Venturi valves in enhancing gas lift performance and maximizing recovery. Field Background The field is divided into four main geographical quadrants, each with its own facilities. Total production currently is approximately 60,000 BOPD with an average water cut of 85%. Exploration and development of the field saw the drilling of more than 460 wells; half of these currently are experiencing reservoir pressure decline, drained reserves, or operational problems. Most wells are gas lifted, and the remainder either use electric submersible pump (ESP) installation or flow naturally. The facility consists of 73 offshore satellite platforms containing the wells—both oil producers and water injectors—connected to nine offshore complex platforms. As a part of continuous improvement trials, the operator reviewed the process of gas lift system management to introduce necessary improvements and recommend changes for long-term plans. The proposed amended management system was the result of monitoring, troubleshooting, and optimization activities outlined in the complete paper. Amended Gas Lift Management System Using Dummy Valves in Gas Lift System. Conceptual Phase. A dummy valve is a special gas lift valve shaped like solid metallic bar with upper and lower packings. They are installed to replace unloading valves that are no longer needed. Installing dummy valves instead of the unloading valves can reduce problems such as valve interference and deepens the point of gas injection. Redesign Procedure Based on the New Production Profile. This practice can be applied in two main cases: First, if reservoir pressure has declined and the well is producing with a lower rate but the surface injection pressure is still high enough to reach deeper valves; and, second, if the well is planned to be recompleted from one formation to another that has a higher reservoir pressure but with lower formation feed as the result of lower productivity. The main steps for redesign are provided in the complete paper.