Abstract:A review of the 137 new (10-5-2000) offshore and onshore E&P blocks of Libya utilised 500 well records, numerous well logs, stratigraphic sections, structural sections, and stratigraphic, geochemical, tectonic and structural maps of Cyrenaica, Ghadames, Murzuk, Sirt, Tripolitania, and offshore Basins of Libya.
Due to the large number of parameters, and to impartially assess, compare, and rank the E&P potentials of the 137 blocks, one map and, a set EXCELس databases were compiled to summarise well data, exploration records, and geological, geochemical, and tectonic parameters of the 137 new blocks:
ط A new well location map of the 137 Blocks (Scale 1/2500) was drafted to illustrate the exploration or production status of the wells within the blocks.
ط The first E&P database summarises the drilling, engineering and geological data per block (31*137 data entries). An exploration risk equation was modified to rank the relative E&P potential of the individual blocks, via comparing the source, reservoirs, cap rocks, tectonics, remaining undrilled anomalies, and exploration results of each block. Three sort variations of the first database were generated in order to rank every one of the new 137 blocks, and to produce 30 charts illustrating:
ط The relative E&P ranks of the blocks of every basin.
ط The relative E&P rank of the blocks for all basins in Libya.
ط The relative size and distribution of the proven, probable and possible discovered hydrocarbon reserves of all blocks.
The second E&P database lists drilling, engineering and geological data, status and results of the 500 wells in all blocks (28*500 data entries). One sort variation of the second database was generated to alphabetically list wells per each block.
1. Introduction:
Records of 500 wells within the new E&P Blocks (11-5-2000) of offshore and onshore Libya (Figure 1) were reviewed through the study, also a large number of documents, well logs, cross-sections, and tectonic, stratigraphic, geochemical and structural maps of onshore and offshore Libya.
1.1. Source Rocks:
Silurian, Devonian, Carboniferous, Triassic, Lower & Upper Cretaceous, Paleocene & Eocene Rocks.
1.2. Reservoir Rocks:
Basement, Ordovician, Silurian, Devonian, Carboniferous, Triassic, Cretaceous, Paleocene, Eocene & Oligocene Rocks.
1.3. Provinces: The blocks were located -according the Libyan NOC, in six provinces. No concession was delineated in the Kufra Basin, which is also open for exploration. However the (NOC) tectonic elements map of Libya indicate the presence of several sub-provincial tectonic elements:
1. Cyrenaica:
Inverted Jabal Akhdar Basin, Cyrenaica Platform, Marmarica Trough As-Solouq Depression.
2. Ghadames:
Ghadames Basin, Al Hamra High.
3. Murzuq:
Murzuq Basin, Dor El Gussa Trough & Gargaf Uplift.
4. Offshore:
Sebratah Basin, Offshore Hagfa Trough, Offshore Agdabia Trough, Benghazi Basin & Offshore Al Bottnan Basin?
5. Sirte:
Hon Graben, Dor Al Abd Trough, Zella Trough, Hagfa Trough, Bu Tumaym Trough, Ajdabia Trough, Hameimat Trough, Maragh Trough, Sarir Trough & Siwa Basin?
6. Tripolitania:
Jeffara Trough & Zamzam Trough.
2. Database as a Ranking Method:
To impartially rank, and illustrate the reasons for ranking the top most promising E&P Blocks; thirty regional source, reservoir structural and tectonic maps of onshore and offshore Libya were updated, and source, reservoir and seal rocks parameters, and past exploration results of each block were listed and plotted.
The ranking of the Block was done objectively by using a RLATIVE E&P POTENTIAL (SCORE); which is a modified risk equation, modified to accommodate proven reserves within the blocks. This equation can be changed should the priorities change (e.g. gas rather than oil), on the spot.
ط One location map showing the location, status (dry hole, oil well, gas well and shows) of 500 wells, undeveloped oil and gas fields, and discoveries within the 137 new (10-5-2000) Blocks (Scale 1/2500).
ط EXCELس Database 1: summarises E&P data, exploration histories, geological etc. and all parameters used in ranking the 137 New Block as 137*31 data entries.
ط Three sort variations of Database 1, which rank every one of the new 137 blocks were used to produce 31 charts illustrating: Dbase 1A the relative E&P ranks of the blocks of every basin, dbase 1Bo and 1Bg for the entire country, and dbase 1C. to illustrate size and distribution of the proven, probable and possible discovered reserves of all the blocks.
ط EXCELس Database 2: lists data, status and results of every well in the 137 blocks as 500*28 data entries. A sort variation of this database (Database 2a) lists the wells per each block.
3. Database No. 1: Ranks, Relative E&P Potentials, and Undeveloped Oil and Gas Fields and Discoveries of the 137 New E&P Blocks in Onshore and Offshore Libya
This Excel Database is composed of 137*31 entries which summarises Target's information and published data on source facies, richness, and maturity, reservoir rocks facies, and the structural configuration of on-and off-shore Libya. The information were checked and synthesised by professionals with long experience with operating oil companies in Libya. The headings of the 31 entries/Block are:
A. 10-5-2000 New EPSA Block.
B. Decimal Long. °E. of the block centre.
C. Decimal Lat. °N. of the block centre.
D. Relative Prospectivity Score, (see footnote).
E. Area of the Block in Kms 2.
F. Proven Oil Reserves (in MMBbls) of undeveloped fields/discoveries if present within the block.
G. Estimated Oil Reserves, (to quantify Probable Oil Reserves =2 MMBbls and Possible oil reserves =1 MMBbls).
H. Proven Gas Reserves (in TCF) of undeveloped fields/discoveries if present within the block.
I. Estimated Gas Reserves, (to quantify probable Gas Reserves =0.02 TCF and possible Gas Reserves =0.01 TCF)
J. Total No. of Wells in the Block.
K. No. of Discovery and/or Suspended Wells.
L. No. of Delineation Wells.
M. No. of Producible Wells. (Wells judged to be completed as a producer)
N. No. of Wells Which Encountered HC Shows.
O. No. of Dry and/or Junked Wells.
P. Kms 2/Exploration Well.
Q. Discovery / Dryholes Ratio (of the wells in the block otherwise 0.1 was used as the average of Libya).
R. Proven and Potential Source Rocks (by age within charging distance).
S. No. of Proven and Potential Source Rocks (to quantify the relative source potential).
T. Proven and Potential Reservoir Rocks (by age within the block).
U. No. of Proven and Potential Reservoir Rocks (to quantify relative reservoir availability).
V. Estimated No. of Undrilled Anomalies (estimate of number of anomaly in the area - drilled wells).
W. Estimated Maximum Size Factor of the Undrilled Anomalies (Small=1, Medium=1.5, and Large=1.75)
X. Depth of Proven and/or deepest Potential Reservoirs (in meters).
Y. Name of Nearest Field or Discovery.
Z. Number of nearest fields and discoveries.
AA. UNDEVELOPED FIELD AND/OR DISCOVERIES WITHIN.
BB. Number of undeveloped fields and discoveries within the block.
CC. Distance to the Nearest Oil Pipeline (in Kms from the edge of the block).
DD. Logistics, water depth and Terrain.
EE. Expected Hydrocarbon: from source rocks maturity and nearby fields
or fields within the block.
RLATIVE E&P POTENTIAL (SCORE) = is a modified risk equation, modified to accommodate proven reserves. This equation can be changed should your priorities change, on the spot.
3.1. Database 1A
As in dbase 1, but blocks of each basin were sorted according to their relative E&P potential per basin/area. Includes relative E&P potential charts:
1. Ranks and relative E&P potential of the new blocks of Cyrenaica.
2. Ranks and relative E&P potential of the new blocks of Ghadames.
3. Ranks and relative E&P potential of the new blocks of Murzuk.
4. Ranks and relative E&P potential of the new blocks of Offshore Libya.
5. Ranks and relative E&P potential of the new blocks of Tripolitania.
6. Ranks and relative E&P potential of the top 25 new blocks of Sirte.
7. Ranks and relative E&P potential of the middle 25 blocks of Sirte.
8. Ranks and relative E&P potential of the last 25 blocks of Sirte.
3.2. Database 1Bo
As in dbase 1, but blocks are sorted according to their proven, probable and possible oil rather than gas reserves in all of the 137 blocks. Include charts:
9. Proven, probable and possible discovered Oil Fields in all 137 new blocks, Libya.
10. Proven, probable and possible discovered Gas Fields in all 137 new blocks, Libya.
11. Relative E&P potential of blocks with discovered (proven, probable and possible) oil fields in all 137 new blocks, Libya.
12. Relative E&P potential of blocks with discovered (proven, probable and possible) gas fields in all 137 new blocks, Libya.
3.3. Database 1Bg
As in dbase 1, but blocks are sorted according to their proven, probable and possible gas rather than oil reserves in all of the 137 blocks. Include charts:
9. Proven, probable and possible discovered Oil Fields in all 137 new blocks, Libya.
10. Proven, probable and possible discovered Gas Fields in all 137 new blocks, Libya.
11. Relative E&P potential of blocks with discovered (proven, probable and possible) oil fields in all 137 new blocks, Libya.
3.4. Database 1C
As in dbase 1, but blocks are sorted according to relative E&P potential. Include charts:
13. Relative E&P potential of the first 20 new blocks, Libya.
14. Relative E&P potential of the second 20 new blocks, Libya.
15. Relative E&P potential of the third 20 new blocks, Libya.
16. Relative E&P potential of the fourth 20 new blocks, Libya.
17. Relative E&P potential of the fifth 20 new blocks, Libya.
18. Relative E&P potential of the sixth 20 new blocks, Libya
19. Relative E&P potential of the last 21 new blocks, Libya
20. Relative ranks and E&P Potential of the 137 new blocks, Libya.
21. Block area vs. relative E&P potential of the 137 new blocks, Libya.
22. Total number of wells vs. relative E&P potential of the 137 new blocks, Libya.
23. Well / Kms vs. relative E&P potential of the 137 new blocks, Libya.
24. Discovery / dry hole ratio vs. relative E&P potential of the 137 new blocks, Libya.
25. Number of remaining undrilled anomalies vs. relative E&P potential of the 137 new blocks, Libya.
26. Average depth of primary reservoirs (in m) vs. relative E&P potential of the 137 new blocks, Libya.
27. Distance to nearest oil pipeline vs. relative E&P potential of the 137 new blocks, Libya.
28 Number of Discovered oil fields vs. relative E&P potential of the 137 new blocks, Libya.
29 Number of proven and potential reservoirs vs. relative E&P potential of the 137 new blocks, Libya.
30. Number of proven and potential source rocks vs. relative E&P potential of the 137 new blocks, Libya.
4. Database No. 2: Wells, Undeveloped Fields, and Discoveries in the 137 New E&P Blocks of Libya
This Excel Database is composed of 500*28 cells/entries (9 to 28 entries per every one of the 500 wells in the 137 new E&P block in onshore and offshore Libya), which summarises Target's information, as well as published technical data on fields and wells in Libya. The information were checked and synthesised by professionals with long experience within operating oil companies in Libya. The titles of the 28 entries/well are:
A. 10-5-2000 New EPSA Block.
B. Well Name.
C. Longitude
D. Latitude
E. Well Number
F. Original Concession.
G. Original Operator.
H. Location.
I. Completion Date.
J. TD in meters.
K. Formation at TD.
L. Results.
M. Field Name.
N. Trap Type.
O. Pay (s).
P. Reservoir Lithology.
Q. Depth of Reservoir in M.
R. Net/Gross Pay Thickness.
S. Reservoir Age(s).
T. °API Gravity.
U. Reserves in MMBO/TCFG.
V. Flow Rate.
W. Production Mechanism.
X. No. of Wells in 1999.
Y. No. of Producing Wells.
Z. No. of P&A Wells.
AA. Present Status of the Field/Discovery.
BB. Comments.
4.1. Database 2A
As in dbase 2, but wells were sorted alphabetically per each of the New Blocks.
5. Conclusions:
This study indicates that database analysis produces an impartial ranking of the relative E&P potentialities of a large number of blocks, and tabulates and graphically illustrates the reasons for ranking the blocks, per basin, as well as per several basins. The results of this analysis (done with equal preference given to oil, gas and condensates) can be summarised in the followings:
1. The new offshore blocks rank higher than the New Sirte, Murzuq and Cyrenaica blocks.
2. More than nine New Blocks have proven undeveloped Oil & Gas fields/Oil & Gas discoveries within.
3. More than 12 Blocks have probable and/or possible Oil & Gas discoveries/Oil and
Gas fields within.
4. Up to 100 MMB Oil or 0.4 TCF Gas of proven undeveloped reserves are within
some of the “new blocks”.
Muhammad W. Ibrahim, Target Exploration Consultants, London
© 2000 Mena Report (www.menareport.com)
