High Resistivity, High Water Saturation

Belayim Land field is one of the oldest and largest oil fields in Egypt. It was discovered in 1954. Its current daily production is about 80,000 BOPD. It produces oil from many sandstone reservoirs, Rudeis, Kareem, Belayim and South Gharib. Rudeis formation is the lowest reservoir in the Anticline structure that forming the field. The sandstone section of Rudeis formation is of an excellent reservoir quality. It is composed of quartz arenite with 22% average porosity and 1200 md average horizontal permeability. The vertical permeability is about 0.9 of the horizontal permeability. The crude oil is of moderate quality with about 20 API. Oil is produced from 10–30 ohm resistivity in Belayim Formation, while in Rudeis Formation; 70-80 ohm resistivity is producing water. A core was cut in Rudeis formation; the wettability of the reservoir rock was determined by Amott method and proved to be strongly oil wet. Electrical resistivity measurements were conducted on restored samples to determine Archie exponent. A constantly variable n values were obtained during the electrical measurements. Two saturation exponents (n values) were proposed to monitor the water saturation in the reservoir. This situation made it deem necessary to propose a certain resistivity cutoff for Rudeis formation in order to avoid perforating water zones