Preliminary Report on Kwanza Basin
Transcript of Preliminary Report on Kwanza Basin
PRELIMINARY REPORT ON OFFERED BLOCKS OF SONANGOL
REPUBLIC OF ANGOLA
PREPARED BY
ABDUL QAYYUM ( MANAGER EXPLORATION, OVERSEAS)KHALID JAVED ( DY.CHIEF GEOLOGIST , OVERSEAS)
1
Introduction:
Angola is world 23rd largest country and second largest country in Sub-
Saharan Africa. It came into existence on November 11, 1975 and has an
area of 1.2467 million square kilometer and population of about 15.941
million people. In general 75% of the population is Agriculture dependent
and has main export of coffee. National Currency name is Kwanzaa and
official language is Portuguese.
Geographic position:
Republic of Angola is bordered by Democratic Republic of Congo in the north
(NE), Namibia in the south and Zambia in the east and Atlantic Ocean in the
west.
Fig-1: Location map of the Republic of Angola.
2
History of Hydrocarbon Exploration:
Hydrocarbon exploration activity dates back to 1910 but first onshore well
was drilled in 1955 in Kwanzaa Basin (Benfica Field). The country first
shallow water offshore commercial discovery was made in 1960 in lower
Congo basin (limba Field). This triggered deep water exploration in 1993
which resulted in another commercial discovery in 1996 in lower Congo basin
(Girrasol Field) . The country moved to ultra deep-water exploration in 1999
and it made commercial discovery in lower Congo basin at Plutao Field in
2002. Since 1996 till 2003, total 55 deep-water commercial discoveries have
been made. The country total oil output is one Million barrels and associated
gas production is 1.20 BCF/day. About 200 exploratory and appraisal wells
have been drilled in the country since
1990 and some thirty companies are
operating in 29 offshore and offshore
blocks out of which 14 are Operators.
Sedimentary Basins of Angola:
Sedimentary Basins of Angola can be
broadly divided into two;
01: Offshore Basin
02:Onshore Basin
Offshore Basin includes; Congo Basin, Kwanzaa Basin , Benguela and Namibe
Basin (Frontier Basin), Whereas, onshore basins include; Kassanje and
Okawango Fig-2: Map showing location of
onshore basins of Angola.
and inner Kwanzaa Basin.
Kwanzaa Basin:
3
Kwanzaa Basin has an aerial volume of 25,000 square kilometers and
extends into offshore. On onshore it consists of 23 blocks, each one about a
thousand square kilometer.
Fig-3: Location Map of offshore basins of
Angola.
M/S Sonangol has offered three blocks in
the Kwanzaa Basin namely Cabinda
Centro, KON-11, KON-12. The blocks have
been imaged by Vibroseis and dynamite
source and have poor line spacing.
Therefore, additional data will be required
to technically evaluate the block as
evident from scattered data in each block.
For quick look, please refer to Summary of
three on-shore blocks
Fig-4: Map showing location of Kon-
11,Kon-12 and Cabinda Centro in
regional perspective.
Stratigraphy of Kwanzaa Basin,
Block-KON-11,KON-12:
Sediments from early Cretaceous to
Pliocene were deposited in the basin with
key reservoirs;
Binga Logoon Carbonates
Catembula
Lacustrine sands and carbonates
4
The basin has proven source rock of Binga and Pre-salt (Albian).
Fig-5: Stratigraphic section of blocks Kon-11,Kon-12.
Seismic Coverage Block Kon-11 and Kon-12:
As evident from blocks layout that
they are contiguous and has poor
seismic coverage. Kon-11 has
32.00 and Kon-12 has about 100
L.km 2D which for a block size of
1000 sq.km is not sufficient to
reasonably evaluate its existing
potential. Aero -magnetic data is
available and its professional
interpretation will be required before envisaging work programme.
Fig-6 : Map showing seismic profiles in blocks Kon-11,Kon-12
Cabinda Centro block:
Cabinda Centro has seismic
coverage of 238 l.km and history of
33 wells with minor oil shows.
Aeromagnetic survey is available
5
and its ingenious interpretation will be required in addition to re-visiting the
old seismic and well histories.
Fig-7 : Map showing seismic profiles in Cabinda Centro block
TECHNICAL SUMMARY /QUICK LOOK INFORMATIONS ABOUT OFFERED
BLOCKS:
Summary and comparison of three onshore blocks is given below in a tabulated form;
CABINDA CENTRO BLOCK-KON-11 BLOCK- KON-12.
Title Cabinda Centro KON-11 KON-12Area sq.km
1425 1020 1024
Wells 33 dry holes 03 expl and appraisal
04 expl and appraisal
Target Fm
Basement cherty L.st. LuculaLacusturine TurbiditeMavumaVermelha
Binga FmCatumbelaLacusturine Sand, carbonates
Binga FmCatumbelaLacusturine Sand, carbonates
6
Source Rock
Bucomazi Binga Fm & Pre-salt Binga Fm & Pre-salt
2D survey 238.50 32.84 99.68Aero Magnetic
Yes Yes yes
Structures
Pre and post Salt Horst structures
Salt induced Salt induced
Oil Fields Nil, only oil shows Galinda &Tobais Pitchy ShowsPotential 250 mm bbls 100 mm bbls 100 mm bblsData Cost US $ 270,000 US $ 140,000 US $ 115,000
BLOCK-KON-11: Key information’s about Galinda &Tobais Oil Fields:
7
Tobais Oil Field:
Wells drilled: 12Datum level: 710 m ssOil wells : 8OOIP: 94 mmblOriginal oil water contact: 850 m ssOil recovery factor: 31%Cumulative oil production: 29 mmbblCumulative gas production: 10 b scfCumulative water production: 3 mmbblOil gravity: 30º APIOil volume factor: 1.129 bbl/stb;Oil viscosity cpo: 3.250Initial reservoir pressure: 946 psia;Saturation pressure: 775 psiaReservoir temperature: 120ºF
Galinda Oil Field
Wells drilled: 8Datum level: 1,901 m ssOil wells: 6OOIP: 21 mmblOriginal oil water contact: 1,970 m ssOil recovery factor: 11%Cumulative oil production: 2 mmbblCumulative gas production: 777 mm scfCumulative water production: 113 m bblOil gravity: 28º APIOil volume factor: 1.180 bbl/stb;Oil viscosity cpo: 2.000Initial reservoir pressure: 5,100 psia;Saturation pressure: 2,058 psiaReservoir temperature: 230ºF
GEOSEISMIC SECTION ALONG TOBAIS AND GALINDA OIL FILED
CONCLUSIONS:
M/s Sonangol has offered onshore and offshore blocks and we have
reviewed the available web data for three onshore blocks, Cabinda
Centro, and KON-11, KON-12.
Cabinda Centro has seismic data of 238 L.km and 33 wells with oil
shows.
Kon-11 and Kon-12 are adjacent blocks, has seismic coverage of 32
and 100 L.km with history of 03 exploratory and 04 exploratory dry
wells.
Three blocks have salt induced tested extensional structures out of
which Kon-11 and Kon-12 has Galinda and Tobais oil Field.
Aeromagnetic data is available for all three blocks.
Basic petroleum system exists in the blocks as proved by the
commercial discoveries; however dry wells history will be required for
8
review as 33 wells in a block like Cabinda Centro must portray solid
technical reasons.
The data shows remaining potential of 100 Million Barrels in block-
KON-11 and KON-12 each.
On the basis of anticipated thick salt in the blocks, seismic imaging is
major technical issue.
RECOMMENDATIONS:
On the basis of very limited available information’s it is extremely
difficult to recommend a block and its data purchase, However,
among two blocks; KON-11 and KON-12, data for either may be
purchased so that could evaluate the block and move forward.
9
10