Evaluation of Reservoir Performance and Technical Challenges for Waterflooding in Heterogeneous Pre-Miocene Reservoir in October Field - Gulf of Suez
Authors: Helmy Ahmed Gamal , Aboelhassan Mohamed Gamil 
Published: March 2023

GUPCO is one of the largest E&P Companies in Egypt and the Middle East. It has a vast infrastructure with a large number of wells, platforms, pipelines, and offshore facilities. GUPCO's peak production exceeded 600,000 BOPD in 1983 while it produces around 100,000 BOEPD today from more than ten geological formations in Gulf of Suez (GoS). Managing giant fields is not an easy task; it requires special knowledge and experience to manage such critical asset since each 1% increment of oil recovery means tens of millions of oil barrels. In this paper, a case study for waterflooding in Pre-Miocene reservoir in Gulf of Suez will be discussed. We will elaborate our experience in dealing with waterflooding in a heterogeneous sandstone reservoir in Gulf of Suez under all levels of field's maturity, highlighting the importance of many tools utilized. Ultimately, proposing guidelines to be followed whilst applying Waterflooding for the utmost benefit.

Over the years, waterflooding has been the most widely used secondary oil recovery method after the exhaustion of the primary depletion energy of the reservoir. Waterflooding schemes have to be planned such that at every point of the operation, net income from oil recovery exceeds operating expenditure of which produced water disposal cost is paramount. Hence, engineers are regularly plagued with challenges such as optimal completions zones for injectors and producers, optimal flood pattern to adopt and number/type of producers and injectors to use in waterflood field development to improve oil recovery, but reduce water production. The aim of this study is to optimize waterflooding from a case study. A simple optimization methodology involving the analysis of the effects of zones of production and injection, pattern of waterflood selected and number/type of producers and injectors on cumulative recovery from a water-flooded reservoir was used.

The different sources of water injection had been used, which are Dump-flood injection, Water source wells and Seawater injection. There were several challenges that had been faced during the life of the field after starting water injection in pre-Miocene reservoir in 1996. Special water injection wells design was implement to account for different zonation characteristics such as installing a dual injector for selective injection per zone, to prevent channeling and water breakthrough time in offset producers. GUPCO already applied TAP (Thermally-Activated Particles) technique in an offset field, which is called commercially BrightWater® to improve sweeping efficiency, and studied feasibility of Low Salinity Waterflooding (LoSal™) which can be studied in near future after upgrading water injection facilities. Diagnostic plot was analyzed and showed pressure maintenance/increment is more effective when there is water injection into more zones of the reservoir and for waterflood operations involving the use of vertical injectors, higher water production rates was observed because water is expected to flow more conveniently in the upward direction due to gravity rather than laterally.