Waterflood Strategy – Challenges and Innovations

Abstract

More than thirty years ago, Gulf of Suez Petroleum company (Gupco) - Egypt, initiated the first waterflood project for El Morgan oil field. The company now operating 14 different waterflood reservoirs. These reservoirs have produced a cumulative oil representing 40% of their original oil-in-place. On average, the projected waterflood recovery factor is 54% of OOIP. Due to non-uniform lithology and non-uniform pattern of existing well locations in most reservoirs, peripheral waterflood was found to be the most suitable and economic waterflood pattern at project startup. Peripheral waterflooding has the advantage that it minimizes the number of injection wells by converting the watered-out producers. As these reservoirs become more mature, the line-drive pattern (peripheral + internal injection) was found to be more effective. Since most of the reservoirs are currently in the mature stage, good managing and close monitoring for each waterflood project is extremely important. This paper projects major strategies in managing the different waterflood projects to maximize both the oil production rate and oil recovery in optimum manners. This is being achieved through several common and familiar waterflood issues including in-fill drilling, zonal injection improvement, injection pattern modification, injection below formation parting pressure, pressure maintenance, workovers for production and injection wells, continuous data collection, and water quality monitoring. The paper also addresses the waterflood side effects such as scale buildup, reservoir souring and facilities corrosion. In addition, the paper discusses some of the innovative techniques that have been used to maximize waterflood recovery and enable waterflooding of marginal fields at a cost effective manner. Examples for these techniques are gas-cap water barrier injection, heavy oil waterflooding, coiled-tube water injection lines, slim-tube dual completions, and satellite waterflooding for pilot and marginal fields waterflooding. Introduction Waterflooding became an important part of most oilfield development strategies in the way to maximize the oil production revenue. A successful waterflood project can efficiently lead to maximize the overall sweep efficiency, which helps in increasing the oil recovery, and to maintain oil reservoir pressure above the fluid's bubble point pressure, which allow for more production rate levels. Several engineering studies were conducted late 1960's by the Gulf of Suez Petroleum Company (Gupco), Egypt, to evaluate the application of the first waterflood project. Strategies and economics of the waterflood project were primarily built based upon three items:projected incremental oil recovery of doubling the primary recovery factor,injection well pattern, utilizing the peripheral injection,water injection plant and injection lines, capacity and location. The company is currently operating 14 different waterflood reservoirs. total incremental secondary recovery has been estimated to be more than 1080 million barrels which is more than double the primary recovery as shown on Fig. 1. Historically, waterflooding in Egypt went through three different stages and during implementation process different strategies and economic models were set to fit the objective of each stage.

Consumptive water use in the production of ethanonl and petroleum gasoline.

“…Although offshore wells could contain both primary and secondary wells (Bibars 2004), no technologyspecific statistics are publicly available at the time of this study. Among the technologies, EOR is onshore operation and well-documented (O&G J 2006) for its production share, while primary and secondary data are scarce.…”