Microbial EOR: First Successful Pilot in Egypt and Middle East
Authors: Mohammed Noureldien Darhim 
Published: October 2022

Since easy oil is diminishing, the entire world started to look after unconventional resources to meet international demand of hydrocarbons. Heavy oil resources represent more than 40% of natural resources within our Earth crust; that is why it has a special focus internationally. Gulf of Suez Petroleum Company (GUPCO) is a leading E&P company that produced c. 40% of Egypt's total cumulative oil to date. In spite of that success, GUPCO recovered only c. 2.0 MMSTBO out of c. 500+ MMSTBO of heavy oil resources in Gulf of Suez. Historically, many efforts were spent in order to exploit such huge volume but in vain due to the reservoir harsh-conditions at which most of conventional approaches fail. This paper addresses successful application of Microbial EOR as Huff'n Puff Pilot to recover heavy oil in Gulf of Suez, Egypt.

GUPCO heavy oil resources is mainly in Nubia formation, October field (offshore). Nubia is a thick fluvial system high quality deep reservoir (11,250 feet tvdSS) with 290 deg. F. temperature, 190,000 PPM Salinity, 14 deg. API, 600 cP viscosity, 2800 psi average reservoir pressure with inter-bedding tar mats. Such conditions (especially temperature, salinity and depth) are barriers for conventional EOR methods especially in offshore environment, and here it comes the special role of reservoir indigenous microorganisms. Indigenous bacteria can be induced by organic fertilizers to produce biological metabolites that may help in recovering heavy oil. The MEOR Pilot was studied in three phases; Phase-1: Sampling & Microbiological Assessment, Phase-2: Lab Experiments & Fermentation and Phase-3: Execution.

A water sample was taken from the heavy oil well, and microbiological assessment concluded presence of five species of indigenous bacteria that can produce biogases, bio-surfactant and biopolymers. Second phase involved fertilizers optimization by addressing optimum P/N ratio, organic/inorganic sources and growth rate in addition to fermentation process in the lab. Several core-flooding tests were conducted to define the prize at core-plug scale. After two years of research, the optimum fertilizer was fermented that resulted in 12% heavy oil recovery for one PV Injected. Third phase was pilot implementation at which 160 barrels of fertilizers were injected into the well. The well was shut-in for soaking for 3 days, and then re-opened. After treatment, the oil API increased from 24 deg. up to 40 deg., oil viscosity from 630 cP down to 390 cP, Asphaltenes content from 14.5% to 9.6% with 412 BOPD gain. By modeling these results, MEOR succeeded to achieve a recovery of 41% of the drainage radius STOOIP that is very promising in flooding applications which is being planned at time being.

MEOR was found very efficient in recovering heavy oil in a technically challenging reservoir. Lab experiments and fertilizers optimization are key stages that have many know-hows. In this paper, laboratory experiments will be elaborated, pilot design and execution operational considerations will be presented as well. This paper is a good example of a typical MEOR study workflow that can be followed by E&P companies need to unlock such challenging resources in their portfolio.