document

Abstract

The first production log in heavy oil in Egypt through y-tool, using a high capacity ESP pump, in an open hole completion was performed recently by Scimitar Production Company in Issaran heavy oil field. The objective of the job was to identify the source of water, evaluate the contributions from the different open hole zones and determine whether or not there is cross flow in this fractured heavy oil carbonate reservoir. These wells had originally not been completed with y-tool. Therefore a special y-tool with high capacity ESP was designed especially for Scimitar by Zenith to be able to log the wells under special dynamic conditions. This was the first application world wide of this y-tool, which was used as a temporary completion in the wells.

Production logging (PL) was successfully carried out in 3 Issaran wells at different rates, to identify the high permeability (super-K) layers dominating production and calculate their pressure/PI. Likewise flow profiles were determined and high water producing layers identified. Shut in surveys were successful in detecting cross flowing layers. Calculated flow profile results matched well with surface measured rates.

PL results had a significant effect upon the Issaran field development plan. Water was found to be produced from layers having resistivity up to 30 ohm-m. This led to an increase in the resistivity cutoff for hydrocarbon production and a reduction in water cut. Hydrocarbon producing zones were better identified and Scimitar decided to abandon open hole completions in future wells and go in for cased hole completions, in order both to control the water production as well as avoid breakthrough of injected steam.

This paper describes the field and gives details on job planning, operations, results and way forward for field re-development.

INTRODUCTION

The Issaran field, situated in the Egyptian Eastern Desert, is one of the few heavy oil fractured carbonate reservoirs in the world (Refs.1 to 3). It has an estimated 700 MMBBLS of 10-12 degree API crude in the Upper and Lower Dolomite reservoirs and the deeper Nukhul reservoir with 10% H2S. Production in 2008 was 5000 STBOPD, forecasted to increase to 6000 STBOPD in 2010. A Cyclic Steam Stimulation (CSS) project was started in Issaran in 2006.

Heavy oil is an unconventional oil resource that is characterized by higher viscosities and densities as compared to conventional oil. Most of the heavy oil reservoirs are deposited at very shallow depths. These hydrocarbons originated as conventional oil that formed in deep formations, which then migrated to the surface regions where the lighter hydrocarbons escaped (Refs. 4 to 7).  Primary recovery from such unconventional reservoirs can be as low as 1%, with ultimate recovery generally being < 30%.

Issaran oil field is located 290KM southeast of Cairo and 3KM inland from the western shore of the Gulf of Suez covering an area of 20,000 acres. The field was discovered in 1981 (Figure 1). The heavy oil project started in 1998 between GPC (General Petroleum Company) and Scimitar Production Egypt Ltd. The OOIP at that time was 410 MMBBL, reserve 0.2 MMBBL, recovery factor below 1% and the daily production was 170 BOPD. The productivity of the wells was very low and the average production per well was below 30 BOPD.