The Key of Success to Manage Shallow Heavy Oil and Unconsolidated Sand Reservoir

Abstract Heavy oil is an unconventional oil resource that is characterized by high viscosities and high densities compared to conventional oil. Most heavy oil reservoirs are deposit in shallow depths. Issaran oil field is located 290 KM southeast of Cairo and 3KM inland from the western shore of the Gulf of Suez covering 20,000 acres. The field was discovered on 1981. The Zeit Sand formation in Issaran is highly unconsolidated sandstone. The oil is 10-12 API. The top of reservoir depth is around 700-800 ft, the thickness is around 15 ft. The initial reservoir pressure and temperature are 250 psi and 90°F respectively. The oil viscosity is more than 4000 cp at standard conditions and the reservoir rock is oil wet with 5-10% H2S content. The highly unconsolidated nature of the sand and the thin pay (heat losses) makes the economical production of Zeit Sand very challenging. The OOIP in the developed area is estimates at around 2.5 MMSTB with estimated 35 % recovery factor using steam injection. The productivity of the wells initially before steaming is very low and the average cold production per well was below 5-10 BOPD. In 2009 Scimitar initiated a reservoir simulation to study the optimum development scenario in term of wells spacing and injection/production scheme. The model assumed there is no aquifer existing (as per G&G interpretation). As of Dec. 2009, it was decided to develop the area based on 150 mt spacing (18 new wells were drilled and 9 old wells have been re-completed in Zeit sand. This project faced a lot of challenge to produce Zeit sand formation either by cyclic steam stimulation or by steam flooding injection in the gas cap or oil leg wells, this paper will illustrate the different phases of this project and the challenges that were faced to complete the wells and handle the unconsolidated sand problem. Every effort was made to keep the cumulative voidage replacement ratio around one and the ultimate steam oil ratio below five which will have adequate reflect on the economics of the projects.