DualEx Energy (DXE.v) and Africa Hydrocarbons (NFK.v) have
set their sights on completion and testing operations at their Bouhajla North
prospect (BHN-1) in the Bouhajla Permit in onshore Central Tunisia. Bouhajla
North is a geological analogue of the Sidi el Kilani oil field located 25km to
the East. A comprehensive review of the Bouhajla North prospect was carried out
here.
The Sidi el Kilani oil field is located in the former North
Kairouan Block in central onshore Tunisia. It was discovered in 1989 by the
Kuwait Foreign Petroleum Exploration Company (KUFPEC), with ETAP, the Tunisian
state company, as a partner. What follows is a comprehensive year by year review
of the oil field since discovery. As Bouhajla North is a geological analogue of
the field, (confirmed by 2D and 3D seismic data plus the recent drilling of the
prospect) the information gathered will enable investors to forecast how
developments at Bouhajla North would pan out should BHN-1 proceed into
production:
1989
In 1989, oil was discovered in apparently commercial
quantities after drilling the SLK-1 well on the North Kairouan Block and
encountering 80 metres of pay. An extended flow test proved that a high flow
rate could be sustained. Detailed seismic surveying was performed to delineate
the productive structure and to give further information on nearby prospects.
Extension for the permit was obtained and a programme of appraisal/development drilling
and further exploration planned.
1990
The first appraisal well of the discovery, SLK-2, begun
drilling in 1990. Drilling was however cut short before SLK-2 reached its full
target depth on 4th August 1990 after the closure of KUFPEC’s Head
Office in Kuwait as a result of the Iraqi invasion of Kuwait. Though the well
had already penetrated the target Abiod chalk, it had failed to encounter the
productive strata that had been encountered by the earlier Sidi el Kilani
discovery. However, the well was temporarily plugged under force majeure, for
possible later re-entry.
1991
KUFPEC resumed work in Tunisia in September 1991.
After operations commenced, an extended production testing
of SLK-1 was initiated. The well commenced production in September at 2,000
bopd and was increased to 2,800 bopd in October. Total oil produced from Sidi
el Kilani during 1991 was 280,000 barrels. The production performance for the 4
months so far was considered satisfactory.
Oil produced was transported by road tankers to Compagnie
Franco Tunisienne des Petroles’ (CFTP) pipeline terminal at Sidi el Itayem. The
oil was subsequently transported by pipeline to the La Skhirra tank farm and
the sea export terminal. The Sidi el Kilani crude was sold to Western Europe as
Zarzaitine Blend.
The 2nd appraisal well SLK-3 was spudded in
November 1991 and was successful in penetrating approximately 130 metres of
prospective Abiod formation and proving oil 85 metres below what was considered
to be the lowest oil at SLK-1.
1992
Testing performed on SLK-3 in early January 1992 produced
clean 40° API oil at a rate of upto 7,000 bopd. As a result, it was felt that
SLK-2 required deepening to penetrate the Abiod formation fully.
Following the successful 6 month long production test which
ended in March 1992, a mining license application was submitted for full
development.
The production for 1992 was 250,000 standard barrels;
equivalent to an average daily rate of 694 stb/d. While awaiting installation
of permanent production facilities and a pipeline, field production continued
utilizing the temporary facilities and trucking.
SLK-2 was re-entered and drilled through the Abiod reservoir
but failed to produce hydrocarbons during testing. Two further
appraisal/development wells were drilled during the year.
The SLK-4 well was completed as a production well and
produced oil at 8,600 stb/d on a 1½" choke.
The SLK-5 well was drilled to appraise the north of the
field and encountered a non-reservoir in the Abiod formation and no testing
operations were conducted.
During 1992, Enterprise Tunisienne D’Activities Petroleum,
(ETAP) the Tunisian state oil company, exercised its contractual option to
participate in the development of the Sidi el Kilani oil field.
1993
The Sidi el Kilani oil field was brought on commercial
production during 1993 utilising temporary production facilities. Field
production to end December was in excess of 2mmstb. The average daily
production rate for the year was 5,622 stb/d.
Significant progress on the development of the SLK oil field
was made during the year. Development wells SLK-3 and SLK-4 were hooked up and
flow lines installed from the wells to the Gas Oil Separation Plant (GOSP). Upgrades
to the GOSP were initiated. This was expected to facilitate an increase in
daily offtakes to around 15,000 stb/d.
A 3D Seismic survey was acquired over the Sidi el Kilani
structure during the year.
1994
The GOSP was installed and commissioned. Following the
interpretation of the 3D Seismic data, an additional development well was
drilled in the southern part of the field. This well, SLK-6, was connected to
the production facilities at a stable rate of 7,000 stb/d. Following the
success of SLK-6, the field capacity was increased to 18, 000 stb/d. However,
oil continued to be trucked to the CFTP pipeline at Sidi el Itayem and production
was limited to 14,500 stb/d due to constraints in crude throughout and handling
capacity.
Further development drilling to confirm the need for a
dedicated pipeline was planned.
1995
Development well SLK-7 was successfully drilled and
completed as an oil producer in September 1995. Sidi el Kilani closed
production at year end with production rates in excess of 18,500 stb/d. The
average daily production for the year was however 15,902 stb/d.
The oil continued to be trucked to the export pipeline at
Sidi el Itayem. In addition, direct trucking to the export terminal at La
Skhirra commenced on 2nd June 1995 following the signing of a MOU
between KUFPEC and Transports par Pipe-Lines au Sahara (TRAPSA).
A decision on whether to build a dedicated pipeline to the
export terminal at La Skhirra or a tie in to the existing pipeline at Sidi el
Itayem was to be made after reservoir engineering studies and economic
evaluations were completed.
Peak daily production from the Sidi el Kilani field was
achieved in 1995 when production was just shy of 20,000 stb/d on one of the days.
1996
Average oil production was 18,076 bpd, an increase of 13%
from the previous year. Sidi el Kilani was now producing almost a third of
Tunisia’s entire oil production. Production continued to be transported by
tanker to the CFTP pipeline at Sidi el Itayem and from there by pipeline to the
TRAPSA export terminal at La Skhirra on the Mediterranean Sea.
Major facilities enhancements were successfully completed
with the installation of an oil cooler to enhance oil recovery, a de-gassing
boot, and a low pressure flare system. Safety modifications continued with
improvements to the fire and gas detection system and installation of a storage
tank deluge system and fire extinguishing system. New fire pumps were installed
and the firewater storage pond was upgraded to comply with international
standards.
1997
Average production at Sidi el Kilani for the year was down
17% to 15,017 bpd. This was a result of the natural decline of the field. Sidi
el Kilani was the third largest producing field in Tunisia after El Borma and
Ashart. Plans were put in place to maximise oil recovery with sidetrack
drilling and recompletion workover of two wells.
During the year, a contract was awarded to construct a pipeline
direct from Sidi el Kilani to La Skhirra at a cost of $12 million. Land
acquisition and engineering design commenced, with the pipeline expected to be
operational in 1999.
1998
The average production for 1998 was 14,702 bpd. Construction
of an 8 inch, 123km pipeline from Sidi el Kilani to La Skhirra commenced. The
pipeline was scheduled to be completed in the first quarter of 1999. By
eliminating the need for transporting oil by truck, the pipeline was expected
to save approximately 6% per barrel in wellhead to market costs and provide
potential for further tariff review.
1999
The 123km, 8 inch overland pipeline with a capacity of
25,000 bopd from Sidi el Kilani to the La Skhirra export terminal was
commissioned.
Production averaged 13,740 bpd, 1,600 bpd higher than forecast,
but about 1,000 bpd less than the previous year. The property now provided
about 1 in 6 of Tunisia’s total production.
Additional developments were undertaken on the producing
Sidi el Kilani property to maximise ultimate recovery from what was now a
mature field. This programme included a re-entry and a horizontal sidetrack,
the drilling of a water disposal well, installation of additional power
generation capacity and improved water treatment and handling facilities.
2000
Advanced isotope tagging technology was utilized in the Sidi
el Kilani reservoir to identify the origins of fluids, recognize
compartmentalization and establish various correlations in the reservoir.
Due to the continuing natural decline of the field, production
(liquids bpd) averaged 12,241.
2001
Average production for 2001 was 7,452 bopd. A detailed
review of the reservoir model was undertaken in order to define additional well
locations. Three locations were identified for drilling in 2002 – a sidetrack
of an existing dry hole, a contingent development location and an independent
closure in the south of the field. The Sidi el Kilani field had by 2001
produced in excess of 42 Million barrels of oil, considerably in excess of
earlier expectations.
2002
Sidi el Kilani production continued to be exported to
Western Europe as high quality Zarzaitine Blend. The field produced an average
of 3,240 bpd. After a full decade of productive life, the field had far
exceeded the most optimistic expectations with total production of 43 Million
barrels.
A successful sidetrack was drilled to stem the decline but
two other planned wells were deferred. The oil field was now being managed
using sophisticated reservoir modeling with a view to recovering the remaining
reserves in the most efficient manner possible.
2003
By the end of the year, the Sidi el Kilani field had
produced over 44 Million barrels of oil. Average production exceeded 2,500
bopd. An additional infill production well drilled in 2002 completed a full
year production and on 15th November a new step-out development well
was spudded.
2004
Average production for 2004 was 2,400 bopd. An additional
development well was completed and put on long term test pending installation
of glow lines to the main plant.
The Chinese National Petroleum Company (CNPCI) farmed in 50%
of KUFPEC’s equity in the North Kairouan exploration block and the Sidi el
Kilani oil field.
2005
Production for the year averaged 1,800 bopd. One water
disposal well at Sidi el Kilani was planned for 2006.
2006
Production exceeded 1,500 bopd in 2006. Drilling of 2
additional development wells was planned for 2006/2007.
2007
Stable annual production of the Sidi el Kilani oil field was
maintained by taking a series of effective measures including intensifying
production performance analysis and dynamic reservoir monitoring, producing
with a rational recovery rate to control the water cut and moderating the
production decline. By the end of the year, production at Sidi el Kilani had
topped 46 Million barrels. Average production for the year exceeded 1,300 bopd.
Drilling of 2 additional wells within a development plan for
2006/2007 resulted in 1 dry hole which was converted to a water disposal well,
and the suspension of a second well pending test results.
2008
By the end of 2008, the field had achieved a cumulative
total gross oil production in excess of 47 Million barrels. Average production
for the year was 1,250 bopd. An integrated field study was initiated in 2008 to
identify any remaining development potential. One development well was planned
for 2009 dependent upon the results of the study.
2009
Sidi el Kilani continued to outperform expectations due to a
lower than estimated production decline rate. Oil production averaged 1,118
bopd.
The Integrated Field Study was completed to define any
possible remaining development drilling locations. One development well was
planned for 2010.
2010
Gross oil production was at 1,040 boepd. A Technical Study
performed in 2010 defined new drilling potential, targeting both shallow
(development) and deep (exploration) targets that would be tested in 2011.
2011
Average production rate for 2011 was 533 bopd. SLK-13 was
drilled with efforts towards the drilling of deep potential targets.
2012
Gross oil production at the Sidi el Kilani oil field in 2012
was about 770 bopd with enhanced performance of the wells. Efforts were continued
in 2012 toward optimizing the field development strategy. Sidi el Kilani closed
the year with 9 producing wells.
And that is the year by year chronicle of the Sidi el Kilani
oil field since it was discovered 24 years ago. It has no doubt been one of the
most important oil fields in Tunisia’s history producing nearly 49 Million
barrels to date.
Originally earmarked to have a 9 year production life cycle,
it has kept flowing for over two decades. This can be attributed to the little
understanding of fractured carbonate reservoirs when the discovery was made.
Much has changed since then. There has been a vast improvement in the
understanding of fractured reservoir models. 3D acquisition and inversion
techniques now allow the building of a requisite model to perform dynamic
reservoir stimulation. Indeed, it is these latest techniques that have
considerably lengthened the production life of Sidi el Kilani.
However, with the field continuing to experience further
decline, the stage is all set for Bouhajla North to step into its shoes as a
significant producer in Tunisia’s oil industry, pending flow test results.
ALL THE BEST.
