SPE Event. 05. April, 2006

1
SPE Event. 05. April, 2006 Stavanger
INCREASED OIL RECOVERY FROM SUB SEA WELLS USING
LOW COST CHEMICAL STIMULATION.
Øyvind Rakstang Advisor, Business
Development, Production Enhancement. Halliburton
AS.
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INCREASED OIL RECOVERY FROM SUB SEA WELLS USING
LOW COST CHEMICAL STIMULATION.
AGENDA Introduction General description Equipment
description Operational procedure Well treatment
technology Example
SPE STAVANGER, 05.04.2006
Øyvind Rakstang, Halliburton AS
3
INCREASED OIL RECOVERY FROM SUB SEA WELLS USING
LOW COST CHEMICAL STIMULATION.

• INTRODUCTION
• A normal well stimulation is done with a rig
  that intervenes the well with a string.
  Normally, this is large operation which requires
  substantial resources and organization. A sub
  sea well stimulation will also often require a
  stimulation vessel.
• This new stimulation method does not require a
  rig and can be characterized as a light well
  operation method without need for string or wire
  intervention. The method utilizes a standard
  service vessel and normal available oil-field
  equipment. The method has been utilized by
  Halliburton in more than 25 operations, and it
  has a number of advantages compared to
  conventional methods
• Low HSE risk
• Low cost
• High efficiency and flexibility

Øyvind Rakstang, Halliburton AS
SPE STAVANGER, 05.04.2006
4
INCREASED OIL RECOVERY FROM SUB SEA WELLS USING
LOW COST CHEMICAL STIMULATION.

• GENERAL DESCRIPTION
• Chemical treatment of sub sea wells from a
  standard service vessel.
• Access to the well via a hose which goes
  through themoonpool in the vessel and down to
  the sub-sea installation.
• The well is treated using bullheading
  technology.
• The pumping of chemicals and fluids is all done
  by external pumps from tanks on the vessel.
  Both internal and external tanks on the vessel
  is used.

Øyvind Rakstang, Halliburton AS
SPE STAVANGER, 05.04.2006
5
INCREASED OIL RECOVERY FROM SUB SEA WELLS USING
LOW COST CHEMICAL STIMULATION.
EQUIPMENT DESCRIPTION

• Moon-pool
• 2x ROV
• Stab-in connector
• Hose/riser ( 50-82 mm/515 M/690 Bar)
• Hoserig with goose-neck
• High pressure/low pressure pumps ( 0-1000 bar)
• Chemical tanks
• Nitrogen equipment (if needed)
• Filter equipment

Øyvind Rakstang, Halliburton AS
SPE STAVANGER, 05.04.2006
6
INCREASED OIL RECOVERY FROM SUB SEA WELLS USING
LOW COST CHEMICAL STIMULATION.
Øyvind Rakstang, Halliburton AS
SPE STAVANGER, 05.04.2006
7
INCREASED OIL RECOVERY FROM SUB SEA WELLS USING
LOW COST CHEMICAL STIMULATION.
OPERATIONAL PROCEDURE

• Observe SIWHP and annular pressure.
• Open well and pump (bullhead) the stimulation
  fluid in to the well.
• Shut in well and disconnect hose/riser and
  hydraulic hose.
• Flow well back to test separator on platform.
• Operation end. Normal production

• Deploy 2x ROV from service vessel.
• Run hose/riser through moonpool via hose rig.
• Run hydraulic hose.
• Install hose/riser on choke bridge on sub sea
  template.
• Perform pressure test.
• Shut in well. (Other wells on template can
  produce as normal.)

Authority requirements. Plattform shall have
controll over well and template during the
operation. Hydraulic fail/safe vale on SS
intervention point.
Øyvind Rakstang, Halliburton AS
SPE STAVANGER, 05.04.2006
8
INCREASED OIL RECOVERY FROM SUB SEA WELLS USING
LOW COST CHEMICAL STIMULATION.
OPERATIONAL PROCEDURE CONT.
Example from Statfjord satellite.
Øyvind Rakstang, Halliburton AS
SPE STAVANGER, 05.04.2006
9
INCREASED OIL RECOVERY FROM SUB SEA WELLS USING
LOW COST CHEMICAL STIMULATION.
WELL TREATMENT TECHNOLOGY
DIVERSION When a fluid is pumped/bullheaded down
a well, it will choose the path of least
resistance out in the formation. Diversion is
about altering the natural fluid distribution in
the well in order to get access to several parts
of the formation.
Øyvind Rakstang, Halliburton AS
SPE STAVANGER, 05.04.2006
10
INCREASED OIL RECOVERY FROM SUB SEA WELLS USING
LOW COST CHEMICAL STIMULATION.

• DIVERTION METHODS
• Ball sealers
• Solids in the fluid that gradually plugs the
  formation
• Mechanical tools
• Viscous fluids
• Foam

Øyvind Rakstang, Halliburton AS
SPE STAVANGER, 05.04.2006
11
INCREASED OIL RECOVERY FROM SUB SEA WELLS USING
LOW COST CHEMICAL STIMULATION.
DIVERSION WITH VISCOUS FLUIDS

• Different types of polymers are used to give
  the fluid required viscosity.
• Choice of polymer is done based on the actual
  stimulation.
• Substantial testing of fluids and formation
  are performed prior to job.

• Most stimulation jobs can be performed with
  viscous fluids - scale removal and
  inhibition - organic/inorganic acid
  stimulation - water shut off/conformance
• After the fluid has entered the formation, the
  fluid viscosity will break so that the
  residual fluid can be easily back-produced.

Øyvind Rakstang, Halliburton AS
SPE STAVANGER, 05.04.2006
12
INCREASED OIL RECOVERY FROM SUB SEA WELLS USING
LOW COST CHEMICAL STIMULATION.

• DIVERSION USING FOAM
• The density of a foamed diverter is only in
  the range 0.003-0.010 Kg/L
• The foam diverter is made by adding a small
  amount of surfactant and nitrogen.
• Foam has very good diversion properties and
  will often be the only diversion alternative for
  wells with low formation pressure.
• Total stimulation effect by using foam is often
  better than using fluids..
• By using foamed diversion only small amounts of
  foreign/unwanted chemicals are introduced to
  the formation.
• Most stimulation jobs can be done with foam.

Øyvind Rakstang, Halliburton AS
SPE STAVANGER, 05.04.2006
13
INCREASED OIL RECOVERY FROM SUB SEA WELLS USING
LOW COST CHEMICAL STIMULATION.
EXAMPLE, WELL TREATMENT WITH GEL DIVERSION Acid
scale treatment. Statoil, sub sea well.

• SCALE TREATMENT
• 25 M3 KCl - brine
• 220 M3 Scale treatment
• 200 M3 Overflush
• 3 M3 Methanol

• ACID TREATMENT
• 20 M3 KCl - brine
• 30 M3 Diverter org. acid
• 37 M3 Sea water
• 3 M3 Methanol

PERM. PROFIL
Operational time (incl. 22 hr. shut-in) 2.7
days
PRODUCTION DATA Oil production prior/after
treatment 88 / 402
SM3/D Water production prior/after treatment
538 / 2850 SM3/D PI
before/after treatment
38 / 128 SM3/D/Bar
Øyvind Rakstang, Halliburton AS
SPE STAVANGER, 05.04.2006
14
INCREASED OIL RECOVERY FROM SUB SEA WELLS USING
LOW COST CHEMICAL STIMULATION.
EXAMPLE, BULLHEADING. FROM VESSEL Scale dissolver
scale inhibitor. Statoil sub sea well.

• SCALE INHIBITOR
• 25 M3 Preflush
• 280 M3 Scale treatment
• 330 M3 Overflush

• SCALE DISSOLVER
• 10 M3 Preflush
• 40 M3 Dissolver
• 55 M3 Overflush

WELL DATA

• MD 4430 M
• BHT 99 oC
• Perm. 1500-2500 mD

3 days/well treatment Treatment cost 4 Mill
NOK Extra cash flow 1,47 Mill NOK/Day
Treatment cost covered in less than 3 days.
PRODUKSJONSDATA Oil production before/after
treatment 30 / 615
SM3/D Water production before/after treatment
100 / 680 SM3/D
Water cut before/after treatment
77 / 55
SPE STAVANGER, 05.04.2006
Øyvind Rakstang, Halliburton AS
15
INCREASED OIL RECOVERY FROM SUB SEA WELLS USING
LOW COST CHEMICAL STIMULATION.
OTHER WELL STIMULATION TREATMENTS WHICH CAN BE
DONE USING BULLHEADING TECH. FROM A SERVICE
VESSEL.

• DISPROPORTIONAL PERMEABILITY REDUCTION
• Well stimulation utilizing this technology gives
  a reduced water permeability to the well,
  while the oil permeability is unchanged.
• Operational equipment and procedures are the
  same for this operation as with other
  acid/scale stimulation.
• Inital tests done on Veslefrikk have given very
  promising results.
• water production before/after 2385 / 1590
  sm3/d
• oil production before/after 145 / 145
  sm3/d

PORE
BEFORE TREATMENT
PORE
AFTER TREATMENT
Øyvind Rakstang, Halliburton AS
SPE STAVANGER, 05.04.2006
16
INCREASED OIL RECOVERY FROM SUB SEA WELLS USING
LOW COST CHEMICAL STIMULATION.

• CONCLUSION
• The presented method is a well stimulation method
  without need for well intervention. The method
  utilizes available vessels and standard available
  oil-field equipment. The method has been used in
  more than 25 sub sea wells, and has shown very
  promising results
• Low HSE risk
• Low cost
• High efficiency and flexibility

Øyvind Rakstang, Halliburton AS
SPE STAVANGER, 05.04.2006