Successful Application of ESP's in a Very Corrosive Environment, Gulf of Suez Area, Egypt (Case Study)

Abstract

The need for artificial lift is very common worldwide, nearly all reservoirs requires artificial lift at a certain stage of the field life. The decision of which artificial lift method to use is very important to the long-term profitability of the field. An improper decision of artificial lift can reduce production and increase the operating costs substantially. Once a decision has been made on the type to install on a well, it can rarely be altered whatever the method been selected. Ras Fanar Field is located on the western side of the central part of the Gulf of Suez about 3 km east of the city of Ras Gharib. Production commenced in January 1984 and a peak production rate of 20 MSTB/D was achieved in May 1984. The field was produced naturally for 14 years and the produced fluid contains up to 15% H2S and 11 % Co2 in the associated gas phase. It has been recognized that there is a need for artificial lift when water cuts increased and/or reservoir pressure decline. Studies carried out by SUCO concluded that ESP's are the most appropriate method and it was installed in 1996. The operating experience gained during the period 1996 to 1998 led to significant improvements, resulting in ESP run lives in excess of three years. The main problems during the initial phase of the project and the applied solutions, as well as critical operating factors will be described. This paper presents and discusses the operational challenges of the ESP in such highly aggressive environment and documents the success and failures. Introduction The Ras Fanar Field, Figure (1) was discovered in 1974 by Shell-BP-Deminex group. It was declared commercial and commenced production in 1984 with six wells drilled. Over two offshore Platforms with an average 8 MBOPD. Since early production, the field has shown a high production potential with a conservative reservoir pressure decline. Due to the relatively low reservoir pressure in the Ras Fanar field, some of the wells experienced lifting problems at water-cuts (~20%), which required nitrogen assistance to restore intermittent production. The reservoir fluid is a 30–32° API with a high sulfur content of about 1.9% by wt. The associated gas is sour containing about 12% H2S and 11% CO2 by volume at separator conditions. Reservoir Description The field comprises one reservoir, namely the Nullipore. It is a carbonate build up (reefal limestone) of the Miocene age. The reservoir is hydraulically communicated, with no sharp boundaries like shale's or anhydrite in between. The major and minor faults are all non-sealing, which results in having the same pressure regime in different wells throughout the field Figure (2) illustrates Structure contour map for RF field. The oil column is approximately 730 ft between the crest at 1900 ft-TVDss and the original OWC at 2430 ft-TVDss. The field always shows increasing oil potential, which resulted in upgrading the reserves several times. Overall 24 wells have been drilled by the end of 1995 in the Ras Fanar area.