Sedimentary rocks that occur in Basins of different geologic time cover over one-third of the surface area of Ethiopia. The Basins formed in the Upper Paleozoic-Lower Mesozoic are known as: the Ogaden, Abay (Blue Nile) and Mekele Basins,

whereas those of the Upper Mesozoic to Middle Tertiary Basins are called the Gambela and Southern Rift Basins. Younger Tertiary rift grabens also occur all along the axis of the East African Rift System.

The Ogaden Basin, situated in the eastern part of Ethiopia, covers an area of about 350,000 sq. km. It contains thick sedimentary succession up to 10 km in the deeper parts, spanning Late Paleozoic to Early Tertiary. Lithologically the sediments comprise deep

to shallow marine and continental sediments. There are two gas/condensate field discoveries in the Ogaden, namely Calub and Hilala. The Calub gas condensate reserve is estimated at 2.7 TCF and that of Hilala is about 1.3 TCF.

The main source rocks in the Ogaden Basin are represented by the Bokh Formation (Permo-Triassic), the transition zone (top Adigrat to base Lower Hamanlei, Early Jurassic) and the Uarandab Fm (Middle to Upper Jurassic), with source potential of 7 kg HC/t, 8.6-20 kg HC/t, and 5.3 kg Hc/t of rock respectively and their respective net thickness ranges up to 300 m, 120 m and 120 m. The hydrocarbons generated are mainly gas for Bokh Formation and oil and/gas for the others.

Rock units with good quality reservoir characteristics include the Calub Sandstone (Carboniferous/Permian), the Adigrat Sandstone (Late Triassic-Early Jurassic) and Middle and Upper Hamanlei Formations (Middle Jurassic, both of which are carbonate units). The Adigrat Sandstone (net thickness up to 135 m) has a porosity that ranges between 10% and 20%, with permeability that reaches up to 100 mD. The porosity and permeability qualities of the Upper Hamanlei

are rather excellent- 20–23% porosity and permeability between 10 and 1000 mD. The Middle Hamanlei has porosity values between 12 and 26% and permeability of 5-6 mD. The Calub sandstone has a net thickness of up to 40 m and a porosity of 7%-20% with a permeability about 10 mD.

Drag folds related with wrench tectonics, domal features and fault blocks have been identified as potential structural traps in several blocks of the Ogaden Basin. Stratigraphic trap conditions have also been recognized in the Mesozoic beds at the southwestern part of the Basin. The Uarandab Formation (mainly shale and marl) is a good regional seal unit for petroleum accumulated in the Upper Hamanlei reservoirs. Shale intercalations and evaporites (anhydrite) in the Middle Hamanlei are also good seal beds that overlie the reservoir units of the same Middle Hamanlei formation. The Permian Bokh Shale and the Transition Zone along with the lower Hamanlei tight carbonates and shale beds make good seal to the Calub and Adigrat reservoirs, respectively.

The Mesozoic Basins of Yemen with commercial oil reserves have corelatable sedimentary sequences to that of the Ogaden Basin. Oil and gas shows in several wells drilled in the Ogaden are promising and call for attention of identifying possible trap seal condition.

Mesozoic Basin with sedimentary sequence comparable to that of the Ogaden. Upper Jurassic Antalo Limestone which is equivalent to Uarandab Formation in the Ogaden Basin is a potential source rock. A geochemical analysis of an oil seep sample from the northeastern end of the Basin (at Woreilu locality) indicated the presence of mature marine source rock. The Adigrat Sandstone, Amba Aradom Formation (Upper Sandstone) and some beds of the Antalo Limestone are considered potential reservoirs.

This Basin, with an area of 17,500 sq. km, lies at the southeast extension of the White Nile Rift of the Sudan which contains the petroliferous Melut Basin. Upper Mesozoic to Palaeocene sediments reaching up to 5000m in thickness are expected to exist in fault-bounded grabens.

Lacustrine shales and associated fluviatile sands are considered potential source and reservoir rocks in the Basin, respectively. Currently the Malaysian company known as PETRONAS CARIGALI is undertaking exploration over the entire expanse of the Basin.

The Omo and Chew Bahir Basins along with other small size grabens that lie within the East African Rift System make up the Southern Rift Basins. From forward gravity modelling it is shown that 3000 to 3500 m thick sediment is expected in the depocenters of the larger Basins. The possible continuation of the older Mesozoic rifts of the Anza Graben of Kenya and the Abu Gabra Rift of the Sudan is also suggested in some studies.

The Basin covers an area of 8,000 sq. km and the Mesozoic sedimentary succession in this Basin is over 2000 m thick. The Adigrat Sandstone (150-160 m) is the potential reservoir, although, the presence of potential source rock is yet to be established.

• Petroleum potential of Ethiopia (Beicip-Franlab 1998).
• The Hydrocarbon Potential of the Ogaden Basin (Alconsult International Ltd. 1996).
• Petroleum Geochemical evaluation (Ogaden Basin).
• Well logs and well reports (46 wells: Ogaden Basin)

• Seismic Data (Ogaden Basin 22,700 line km).
• Landsat structural study SW Ethiopia: Gambella-Omo area)
• Gravity and Aeromagnetic data (Ogaden– Abay river –Gambela area).
• Geochemistry and Petrophysics laboratory analysis.

Petroleum agreement will be in the form of Model Production Sharing Agreement of 1994 or Modern Concession contract to be signed between the Government of Ethiopia, represented by the Minister of Mines, and a Contractor.

1. SPECIFIC TERMS AND CONDITIONS FOR APPLICATION

Applications from individual companies as well as from groups of companies will be considered.

2. SUBMISSION OF APPLICATION
1. Address for submission of application

An application should be made to:

Minister (_________)
Ministry of Mines & Energy
P. O .Box 486.
Addis Ababa, Ethiopia
     

It should be submitted in a sealed envelope delivered by certified mail or hand. The envelop must be marked:

	"Confidential"
	"Proposal for Petroleum Exploration
	 and Production"
     

There is no payment of any application fee.

   ii  Content of an Application

Presentation of applications shall be in accordance with the provisions of the following Section IV.

All documents concerning an application shall be kept confidential by all parties.

   iii  Inquiries

Any information or clarification or the submission of an application may be obtained from:

	Petroleum Operations Department
	Ministry of Mines & Energy
	P. O. Box 486
	Addis Ababa, Ethiopia
	Tel: 	251-1-646-12-09
		251-1-646-12-08
	Fax: 	251-1-646-34-39 or
		251-1-646-33-64 

After having examined the applications received, the Government may at its sole discretion invite a successful applicant to appear in Addis Ababa for negotiation.

1. A petroleum agreement will be signed with a successful applicant upon the conclusion of negotiation in a manner satisfactory to the Minister of Mines. It is the wish of the Government that the agreement reached shall be effected as soon as possible.

2. The Minister of Mines reserves the right to accept or reject any proposal, without being obliged to justify his decision on the subject.

   iv  FORM OF PRESENTATION AND
       CONTENT OF APPLICATION

1. An application in respect of all blocks should be presented in a sealed envelope. An applicant may apply for more than one block. An application may be made by a company or group of companies.





2. An application shall contain the following:





1. the identification of the block(s) to which the application applies;

2. Each applicant should notify of;




• the name and address of the applicant in full;

• the nature of its business;

• the place of incorporation;

• the principal place of business;

• evidence of the financial standing and technical qualification and experience of the applicant, including a copy of the most recent audited accounts of the applicant and of any body corporate having control of such applicant;

• the name and address of duly authorized agent in Ethiopia, if such agent has been already appointed by the applicant at the time of application;





3. Where the application is made by a group of companies, information under paragraph (b) will be provided by each company; the name of the operator and the participating interest of each company will be also provided;

4. The terms proposed by the applicant in respect of the major aspects of the model agreement.



3. ASSESSMENT OF APPLICATION




In assessing applications, the Government shall focus, among others, on the following:

1. Minimum exploration work and expenditure obligations;

2. The economic benefits to the country, with emphasis on Profit Oil sharing;

3. The applicant's proposal regarding natural gas.





ADDIS ABABA, April 1994
THE MINISTRY OF MINES AND ENERGY

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