The Abu Gharadig Basin in the Western Desert (NW Egypt) is a mature hydrocarbon province with over 95% of the oil and gas fields in the Upper Cretaceous Abu Roash, Bahariyah and Kharita sandstone reservoirs. Many wells had penetrated the thick Lower Cretaceous Alam el Bueib sandstone reservoir but no significant discoveries were made. This led most operators to believe that there was very little prospectivity at deeper levels, in particular in the Jurassic Safa sandstones overlying the Palaeozoic basement. Shell acquired the North-East Abu Gharadig (NEAG) Basin Exploration License of almost 10,000 km2 in 1996 with parts covering a proven structural trend with several Upper Cretaceous opportunities. Information of existing wells in the concession also indicated the presence of Jurassic reservoir/seal pairs underpinned by oil shows. After a disappointing initial exploration campaign focusing on Cretaceous targets, Shell shifted focus to the Jurassic play. In 2002, the JG-1 exploration well found 6 m of light oil pay in Lower Safa sands at 3,200 m depth and proved commercial flow rates. Five additional appraisal/development wells and 3D seismic have outlined an oil-rim field in a fault-bounded, compartmentalised, dip-closure with significant lateral variation in reservoir quality/distribution. The field is currently producing at rates of 30 MMscf/d and 5,000 bbl/d under primary gas cap expansion drive. Based on the commercial success of the JG discovery further exploration activity in the Abu Gharadig Basin continues to focus on the Jurassic play which has larger volume potential than the traditional Upper Cretaceous plays. The presentation will cover the exploration strategy, the discovery and early development of the JG field and the JG field development plan. The story of the NEAG concession demonstrates that lucrative opportunities in mature basins remain if comprehensive data analysis is combined with creative thinking and perseverance. Introduction This paper describes the activities that led to the discovery and development of a deep Jurassic play in the ‘mature’ Abu Gharadig basin, Western Desert, Egypt (Fig. 1). Over 95% of the oil and gas fields in the Abu Gharadig basin are from Upper Cretaceous Abu Roash, Bahariyah and Kharita sandstone reservoirs (Fig. 2). Many exploration wells had penetrated the thick Lower Cretaceous Alam el Bueib sandstone reservoir but no significant discoveries were made. This led most operators to believe that there was very little prospectivity at deeper levels, in particular in the Jurassic Safa sandstones overlying the Paleozoic basement. In this paper we describe how Shell Egypt N.V. and its operator Badr el Din Petroleum Company uncovered a new play and subsequently developed it within the tight time constraints of an Exploration Concession. First we describe the recent exploration activities and the petroleum systems that led to the discovery of the Jurassic play. Subsequently we describe the phased development strategy adopted and the technological challenges faced when developing a new play.

The JG field is located in the North East Abu Gharadig (NEAG) Basin of the Western Desert in Egypt. With first production in 2002, it is the first commercial discovery in the Middle Jurassic Lower Safa Reservoir Units in this basin. Oil and gas are produced from the tidally influenced estuary channel deposits in the Lower Safa A Unit and oil from the massive braided fluvial channels in the Lower Safa C Unit. At first, the field was believed to consist of one single hydrocarbon column. However based on production behavior and additional well information it became apparent that the field was highly compartmentalized in the vertical and horizontal domain. Since then multiple data sources have been leveraged in order to obtain better compartment definitions: 3D seismic, logs, PVT data, geochemical fingerprinting, repeat pressure surveys and production data. The boundaries between the reservoir compartments are defined by a combination of faults and stratigraphic heterogeneities. Although clear in places, some compartment boundaries can only be defined from non-geological data sources. Understanding these heterogeneities and compartment boundaries is essential for optimizing the field development. Like so many fields the JG field proved to be more complex than initially expected. It is argued that extensive data gathering, in particular in the early field development, is essential in helping to timely identify and properly define such complexities. Introduction The Abu Gharadig basin in the Western Desert of Egypt (Fig 1) was generally considered to be a mature basin with over 95% of the oil and gas fields in Upper Cretaceous Abu Roash, Bahariya and Kharita sandstone reservoirs. Shell Egypt N.V. (52% (operator), Apache 48%), however continued to explore for deeper targets in its North East Abu Gharadig Exploration License, in particular in the Jurassic Safa sandstones overlying the Paleozoic basement (Fig. 2). This perseverance paid of with the 2001 NEAG JG-1 well which, at a depth of 3,250 mbdf, found three oil-bearing channel sands in the tidally influenced estuary deposits of the Lower Safa A. A 6m net (20ft) oil-bearing channel sand tested 4,100 bbl/d of 36ºAPI oil with a 1,300 scf/bbl GOR (Ref 1). The JG discovery was brought on production in 2002 and as such constitutes the first commercial discovery in the Lower Safa Reservoir Units in the Abu Gharadig basin. Including the discovery well, a total of 9 wells and one sidetrack have been drilled to date (Fig 3). The information of these wells in combination with production and well and reservoir surveillance data significantly improved the understanding of the field. At first, the field was believed to consist of one single hydrocarbon column that, in places also extended into the massive braided fluvial channels in the Lower Safa C Unit. However with time it became apparent that the field was highly compartmentalized in the vertical and horizontal domain. Since then, multiple data sources have been leveraged in order to obtain better compartment definitions: logs, RFT's, PVT samples, geochemical fingerprinting of oil samples, repeat pressure surveys and production data. The boundaries between the reservoir compartments are defined by a combination of faults and stratigraphic heterogeneities. Although clear in places, some compartment boundaries can only be defined from non-geological data sources. Understanding these heterogeneities and compartment boundaries is essential for optimizing the field development vis-à-vis different depletion rates, drive mechanism and production optimization. This paper builds upon earlier published work 1 but will focus in more detail on the reservoir compartmentalization issues. In particular it will discuss the data sources used, interpretation and integration of the data, definition of the compartment boundaries and the impact on field development.

TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractThe Obaiyed tight Gas-Condensate field was discovered in 1992 and following 4 appraisal wells and 3 additional exploration wells the first integrated field development plan was issued in 1996. This formed the basis for an agreement to deliver 300 MMscf/d. The field was brought on stream in 1999 reaching full capacity in 2001. However, reservoir pressures dropped much faster than expected (30% rather than expected 10% annual production decline). In addition condensate production only reached 60% of initial expectation levels.A complete subsurface review in 2000-1 showed 5 key areas of concern that requiring specific attention in the FDP update: [1] more severe reservoir compartmentalisation, [2] poorer reservoir quality in NW part of the field, [3] lower CGR's, [4] Temperature constraints on flow lines, [5] Multiple fluid contacts. Consequently expected production levels and recovery factors had to be adjusted downward. A root cause underlying most of these issues (points [1], [3], [4], and in part [5]) can be traced back to the design and duration of the early well tests.Three years after the integrated review the reservoir/well behavior is very much in line with the 2001 model, indicating the quality work done at the time.Based on the above solid models, the future development of the field has been optimized. It comprises the following key activities:• Improved field & reservoir management • Full field booster-compression • Production acceleration • Under Balanced Drilling The aim of the paper is to present the Obaiyed Field Development case, lessons learnt, remedial action taken and future plans.

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