1. International Pipeline & Gas Utility Operations, Design & Maintenance

2. Offshore Savings
Operator As Contractor Saves
Offshore Installation Costs
Included in the work spread was a 116 ft. by 52 ft. by 9.5 ft. barge equipped with
a 90-ton crawler crane for lifting and pile driving, installing risers and pipeline
tie-ins, and providing a working surface for infield fabrication.
by Scott Hagood, Anadarko
Algeria Corp., Houston;
Edward Perera, lntec Engi-
neering, Houston; and Tahar
Hadji, Tunisian British Ser-
vice, Sfax, Tunisia
C
ercina oil field. loc:ited in the
hallo"· 'aters off hore Sf:tx.
Tunisia. is operated Tunisian
British Sen-ices <TBS>. a joint ,·enrure
company O'ned by BritL"h Gas Tuni-
sia. Ltd. and Enterprise Tuni·ienn1:
d'Activities Pecrolieres CETAPl. Field de·
velopmem began in early 1993 " ·ith
initial production achie,·ed in ~fa·
199-1. Economic viability of thb project
" ·as maintained by optimizing rhe de-
velopment plan. panicubrly h~· inswll·
22 Pipeline & Gas Journal Augu~1 199">
ing pipdines and rel:ned foc:ilitie-,.
: prim1:· example of project opti-
mization 'a:. in the decision to -;eJf-
direct the installation rather than con-
tract ir to an off-.hore in"t:tll:11ion con-
'itructor. ~df-directing the in-.talbtion
pro,·ided the ac.h'antage-, of lower
co~r....•1n.·eleration of the project
schedule. flexibility and imprcl·ed
co111rol o f operation'. c1p:1hilit,· of
using loc:JI -.upplil:r:-. anJ '>en ice~.
and an opportunity to tr:in-,fer tech-
nolog~· from a fe kl'~· exp:ttrbte per-
sonn1.:I to Tuni...ian 'taff member-;.
Utim:llely. tol.ll co' t of the off-
-;hore in.;tall:nion and hookup of four
platform-, and two pipeline hundk'
was :,3. 1 million. Thi:- rvpre~ent;. a
~:ffing-, of · =;."1::, million or 02"• :i-,
compared to :in "8.H"i million lump-
'Ulll hudgL't prit'I.' de d oped for the
::.aml.' ~cop1.: of ork.
Sa,· ing~ of l-t0 11 Wl.'n:: realized in
the o,·er:tll project budget.
Development Plan
''ater dl:'pths in the Cc.:rcina fide!
cont:lin1:•d 'ithin the Kl.'rkenn:th X11.'St
Pl'rmit of onshore and offshore Sfax
,·:iry from six to l 1 f1. TB . the joint
,·enturL' oper:l!or. disco,·ered the
Kerkenn:th ''orth =I <KK:-1) ·ell in
February 1992. This was followed by
the sub~equem sun:e~~ful exploration
wells. KK:'-2 and KK''-3. Aftl.'r fur-
ther appr:1isal drilling. the field was
determined to be economically ·iable
:ind a de,·elopment pl:tn 'as submit-
ted and :tppron•d in February 199j.
.- t o-ph:tse :tppro:tch was called
out in the dl.''elopment plan. Phase I
would consist of an early production
s~ stem <EPSl ro prm ·ide an acceler-
.tted c:tsh flow. Acqui~ition of reser-
'Oir d:ll:t during Ph:tse I ·ould allo'
further field "''·aluation prior to com-
mitting capital exp<:nditurcs for Phase
II. The EPS schem<: utilized tht' three
original discon~ry wells. each 'ith its
o·n wellhead protector platform .
Each ·ell would produce 'ia a +in.
production tlm'line co :t central gath-
ering facility for pro t.'Ssing crnde oil.
After prrn:e1>sing. oil 'Ould he loaded
onto shuttle hargl.'s for transport.
In:>tflll11L'nt gas. and. e·entu:illy.
gaslifr g:t~ 'a~ w be ddi'ered to each
wellhead ,·ia :1 2-in. pipeline bundled
with the 1-in. tlo'lirn.:. X'ith thesl.! acl-
clition..<;. the entire off~hore dl.'n:lop-
mem ':t~ to con~bt of three '1.'llhe:td
pl:trforms. a manifold gathering pl:tt-
form. a sdf-ell.',·:ning production h:trge
'ith proce,sing equipment. and two
-t-in. x 2-in. pipeline bundles " ·ith a
tot:tl length o f fin~ miles. Leased
equipmc-nc " oukl bl' us..:d w henen :!r
possible to minimizl' capital outlay.
Thb accelerated the project by elimi-
nating time:: required to design and
fabricate nc::w. site-specific equipment.
Installation o f the:: platforms.
l:'quipm<:nt. ~ind pipelines was seen
·'' a typical :-.h:illow-'ater project
" ·hich could he done hy rendering a
turnk<:y projl'ct 10 a qualified offshore

3. contractor. It ·as en'isioned th:u
platforms ,,·ould be installed "ith a
conv<::ntional shallo w-draft. crane
barge and pipe laying by laybarge.
The budget price. utilizing input from
various interested contracto rs. of
58.85 million ·::is de,·eloped for the
total workscope.
ince no experienced offshore in-
stallation contractors 'Crt: located in
Tunisia. a lump- um. turnkey tender
packaged was generated and issued
to ,·arious established. pre-qualified
contractors in Europe and the U. . Si-
multaneously. a TBS project team de-
veloped a cost estimate for self-direc-
tion of the acti'ities as an alternati·e.
Evaluation of tender responses
sho·ed agreement with the budgeted
costs whereas a self-direct installation
wa expected to co·t 5-1.') million.
Advantages and Cost Savings
The high tender price dearly ·as
not feasible ·o. therefore. the alter-
nate self-directed plan was proposed
to management. Advantages of this
plan 'S. the lump-sum. turnkey ten-
der ,,·ere:
£. Cost. 'elf-directed in ·tallation
was estimated at a maximum of 5-1.5
million vs. 58.85 million from con-
work with lm:al
contr:tctors. Thi~
allows payment in
local curn:m:y
<minimizing ex-
penditures in h:.trd
curn::ncy ). pro-
'ides employment
( 2.700 m:m-days
for this project >.
and drects a tmns-
fer of technology
so that the country
can continuallY in-
crease its self-~uffi­
ciencv.
£.· Flexibility.
tractors tender ·. In a self-directed in-
·t:ilbtion. there i- no requirement for
profit. A profe sional contractor usu-
allv achie,·es a minimum of 20°0
profit on each job to cm·er m·erhe:id
expenses. This amounts to i.-- mil-
lion on the budgeted contract.
-s..."'llulllllMiolt
cosl&, ...,,,,,, mobllizo-
"°"ofOlltnMpent>wl
111111 equlpnlnl, 111111 lllllS of
r,ompkliml ~ rNllW by
•lf-tllNdlng II# o./fslltn
Jtll#ll•projfJCI.
·econdly. there are no high costs
of mobilizing outside personnel and
equipment ince TI3 wa located in
Tunisia. local markt:ts wen: sl!arched
for equipment and Tunisian national ·
fulfilled personnel requiremt:nts. ~lo­
bilizarion costs ,,·ere trimmed by
1.23 million.
TBS would install the pipeline by
tow rather than with co1wentional
pipelaying barge . Contractors pre-
pared tenders based on installing the
pipeline hy com·erting a cargo barge
to :.i spud lay barge and calking the
pipe join~ in a con'entional manner.
This is a slow method clue 10 the time
required for " ·elding and radiography.
Also. this method is susceptible to in-
terruptions due to severe weather.
thus increasing cost to the operator.
In TB · plan. pipeline installation
was done ,.ia a series of tmvs. All
pipe welding :tnd makeup activities
occurred onshore. 15 miles from the
installation site. Onshore fabrication
u ·eel 100°0 local labor and experi-
enced minimal exposure to adverse
weather conditions. Actual offshore
inst~illation required l-1 days with
towing ,.s. a bidder's estimate of ten
days ,·ia con,·encio nal pipe laying
methods. Total cost for the pipeline
installation was S-183.615 compared
l o the budget price of 52.23 million.
£. Accelerated schedule. The
contractor who proposed the least
co ·t projected offshore installation
during the summer of 199-+. A self-di-
rected schedule pre pared by TB
showed completion in May. thus ac-
celerating the schedule by as much as
three months.
£. Local Content. As with all na-
tions. Tunisia wants to accomplish
work and lifting
'essds: locating.
procuring . ;ind
preparing a n un-
an:t'pt;1hlc o n-
shore lm::llion for
pipelint.: to"; and
dendoping :1
projt'ct contract
philosophy.
TBS's contract
philosophy ls
summarized by
the following:
£. When pos-
sible. contr:tl'ts
would he exernrcd
on a lump-sum ba-
sb.
With an emphasis
on cost control.
self-directed instal-
lation prm ·ide<l a
great amount of
flexibility. Br elimi-
nating possible pre-
Pipeline welding began in December 1993 by fabricating 21 strings each of 4-
in. and 2-in. pipe. Each string was 1,345 ft. long.
£. Paym ent
wo uld be made
o nly upon com-
pletion of work to
provide maximummium charges for additions or chani.ws
to the original work scope. Tl3S could
cominuallr mcxlify and impro,·e the fa-
cility for no additional rnst. Also. when
we;ither or material dcliwies impacted
progress. the installation plan could hi:.'
mcxlified and work continued r:tther
than incurring downtiim: costs.
Preparation for Installation
After managemc111 appro,·ed the
self-directed installation acti·ities. a
proj1:<.'t tl'am was formed. key pcrson-
nL'I idt.:ntified. and joh re~ponsihilities
,,·1:rc a~sign1:d. Initial work fon1~1:c.I
on lm::iri ng and contracting suitahl1::
inn~nti,·1: for timely compktion. Since
indi,·idual wo rk scopes were ex-
pected to require a maximum of two
months for completion. TllS deemed
it reasonable that a contrnctor would
prn,·id c required working capital
with no immc::diatc:: p:1ymc::nts.

4. • Penalry clauses " ·ould he applied
for schedule deht'S.
• Use of subc~nrracrors 'Ould be
minimized to ensure projecr conrrol
and eliminare o,·erhead cosrs inciden-
tal to SLtbconrracting.
Where required. conrr:icrs Yere
execurecl on a clay rare or unit rare
basis. Day rates included offshore la-
bor. inspection ser'ices. constrncrion
vessels. offshore posirioning. and pile
clri'ing. Unir rates were c:illed out for
accommocl:itions :incl meals.
A tender package describing rhe
scope of wo rk and minimum re-
quirements for construction ,.e sels
<;•;as prepared and issued to
Tunisienne. Jlecliterranean. and Eu-
ropean broker " Follo wing sire 'isits
to Malta, Sicily. and France. a con-
rracr was ler for the construction
spread. Incluclecl in rhe spread was
a 116 fr. by 52 fr . by 9.5 fr. barge
equipped with a 90-to n crawler
crane for lifting and pile dri'ing. in-
sralling risers and pipeline tie-ins.
and providing a working surface for
infield fabrication.
Two small tugs of .+oohp. and 750
hp. were contracted for transporting
personnel, moving the barge. and
pipe towing. Also, a smaller. self-pro-
pelled barge <65.5 ft x 23 ft. x 5.5 ft..
260 hp.) was included to supplemenr
the larger barge during hookup op-
erations. Both barges were fitted " ·ith
spud wells rather than anchors for
ease of mooring.
Concurrent with contracting and
mobilization of constructio n ves·els.
a parcel of land was located and
contracted for use 'hile weld ing
and assembling pipeline bundles.
The selected site measured 1.--175 fr.
x 245 ft . and would accommodate
desired piping and 'Ork arrange-
ments. Requirements for this X'Ork
site included: C1> a steep nearshore
region to allo"'· tOYing 'essei(sl to
approach near to rhe pipe end. (2>
easy access under all x·eather con-
ditions. C3l positioned so as to mini-
mize length of the to' ro ure ro rhe
field , (4 ) located in an area 'X-hich
avoided hea')' sea traffic. and (5) a
single lando'X·ner "·ith which ro ne-
gotiate.
A compromise "·as reached since
the site had an extremely shallow
nearshore region. Ho 'e·er. this
was reaso na ble since areas 'irh
steep nears hore regions 'ere al-
ready used as ports and harbors.
Site preparation began immediately
with le·eling follo'ecl by construc-
tion of sa nd berms ro sen-e as
Construction of the platforms was completed in February. Installation and
pile driving on four permanent platforms required 14 days after which the
jackup barge/production facility was towed to the site and installed.
piperacks. After stringing pipe o n
the sand berms. a lump-sum conrract
'as ex<:cutt!d for pipe·elding and
radiographic inspection serYices.
Pipeline Yelcling began in De-
cemher 1995 and included fahrica-
rio n of 21 strings each of +in. and
2-in. pipe.Each string 'as 1..3--1'1 ft.
long and 'Ork ':ts to he completed
in .30 days. A lump-sum payment
·ould IK· made at that time. During
the follo'ing .J;1nuary and February
l99 1. pipe strings " ·ere cleaned by
pigging to ensure remo,·al of debris
which could affecr post installario n
pigging. Also . a holida y derecror
was used ro inspecr and ,·crify in-
tegrity of the pipeline coating and
any necessary repairs ,,·ere made.
Bracl.!ld-rype anode:, 'ere installed
for corrosion protecrion and pipe
bundll's co nsisring of o ne 1-in. and
one +in. pipdine srring were steel
banded. Flotation de·ices " ·ere in-
srallcd e·e ry 10 fr. as required to
achie'e huoya ncy.
Construction of the rlatforms 'aS
completed in February and an order to
mobilize 'as issued to the construc-
tion n.'ssel surrlier. Jnsra!lation and
pill' dri'ing on the fou r 1x ·r111anenr
platforms required l--1 clays :1fter Yhich
rhe jackup h:trge production facility
':ts tm·ed to rhe site and insr:tlled.
Onh· 18 cl:t'S 'ere needed ro in ·tall
rhe pl:mned. fiw plarform srrucrures.
After installing rhe platforms. pipe-
line WYs began. A - 50 hp. tug ro'cd
1..3-1'1-ft. pipe bundles into rhe field
·here a crane barge would perform
tie-ins. In a parallel operation. the
smaller. self-propelled barge was
completing hookup of the platform.
Pipdine to'ing depended upon high
tide condirions since the onshore site
had a gradual slope in the nearshore
region. This required the towing ves-
sel to remain a half mile offshore .
Tm'ing began with the placement of
a pipe bundle on the launchway roll-
ers and rhen pulling/pushing it off-
shore 'ith a rractor and cleaclman ar-
rangement. Local fishing boats were
hired to hold tension on the pipe
pulling head and to direct the pipe to
a 'airing tug.
Onshore pipeline tie-ins could not
be made prio r to the to'X· so. upon
pulling one 1..3--15 ft. bundle off the
launchway. a second bundle was at-
tached to the first 'ith a cable.
shackle. and swi,·el. The acrual to'
route 'as straight. 15.5 miles long.
and had a minimum interaction 'ith
other ·esscls. All tO'S were com-
plered une,·enrfully in 19 clays. Fol-
lo'ing installation. all pipelines were
pigged and hydrotestecl prior ro com-
missioning.
The Cercina field Yas commis-
sioned on ;lay 19. 199'1. Not only was
it a significant e·enr for Tunisia. but
also ir prodded :111 example of a joinr
n ·nture company successfully com-
bining incountry kno'leclge and abil-
ity 'ith specialized expatriate exper-
tise to achie'C project goals in an effi-
cienr manner. P&GJ