Water control

WHYWATER CONTROL?
 For every barrel oil we produce 3 barrel water.
 For a typical well with 80% water cut the we spend
$4 /bbl for water
Reasons of additional cost
Lift and separation
Treatment & disposal
Corrosion & Scaling
Formation damage, loss of productivity

WATERTYPES
 Sweep water - Helps in Producing
1. Active aquifer
2. Injection water
 Good water – Unavoidable
1.Water in oil at OWC
2. Oil in water emulsion
3. Injection water
 Bad Water – Avoidable
1.Water competing with oil
2. Mechanical failure
3. Operational mistake

GOOD WATER
THEWATER WHICH NEEDSTO BE PRODUCEDWITH OIL.
IT CANNOT BE SHUT OFF WITHOUT SHUTTING OFF OIL.
Injector
Producer
Injector
Injector

DOWNHOLE SEPARATION MAY BE
A SOLUTION.

BAD WATER
WATER THAT IS PRODUCED INTO THE WELLBORE AND
PRODUCES NO OIL OR INSUFFICIENT OIL TO PAY FOR THE
COST OF HANDLING THE WATER.
Coning
Crossflow
BreakthroughRise of OWC
FractureChanneling
Casing Leak

- CHANNELING -
FLOW BEHIND CASING

FRACTURE OR FAULT FROM AWATER
LAYER

INJECTION WATER BREAKTHROUGH
Injector
Producer

WELL DIAGNOSTICS & CANDIDATE
SELECTION
Key to water control is proper diagnosis :
1) Screen wells suitable for water control
2) Determine the type of problem
3) Find the correct water entry point
4) Find the best control system
5) Find suitable placement method

1) SCREENWELLS SUITABLE FOR
WATER CONTROL

DETERMINETHETYPE OF PROBLEM &
FINDINGTHE CORRECTWATER ENTRY POINT
 The key to water control is diagnostics—to identify the specific
water problem.
 When a reliable Production history is available, it often contains
a wealth of information that can help diagnose water problems.

2) CORRELATIONOF ANY PRODUCTION PERFORMANCECHANGEWITHWELL
WORKOVER, EVENTS, PRODUCTION CONDITION CHANGES
 Chokes, separator pressure etc
 Drive mechanism changes (eg. pressure decline below
bubble point) etc.
 Reservoir intervention (onset or change in IOR/EOR
process)

3) DIAGNOSTIC PLOT
ANALYSIS
• Used to help determine the Specific Problem
type by making comparisons with known
behavior patterns.
• Examples:-
1) Indicates flow through a fault, fracture or a
channel behind casing
2) Edgewater flow
3) Buildup of a water cone early in the well’s
life

FROMWHICH POINT ITWATER/GAS IS
ENTERING FROM?
4)Well and reservoir information review (wellbore Profile, tubing
integrity test, well logs, reservoir and fluid properties, geology,
core reports etc)
5) Reservoir OWC/GOC history and relative well position (depth
and space) correlation of neighboring wells - fluid contact
movement data analysis
6) Reservoir simulation results analysis
If the pre-screening work succeeds in diagnosing the problem,
one can run simple economics to exclude obviously uneconomic
candidates at this stage.

WELL DIAGNOSTICS & CANDIDATE SELECTION
TOOLS &TECHNIQUES
Well log Diagnosis
1) Fluid contact logs (e.g. Pulsed Neutron Capture tools, Gamma Ray
Spectroscopy (saturation )Tools etc.)
2) Water movement detection logs (eg. radioactive surveys likeWater
Flow Log, Hydrolog etc.)
3) Production logging combination tools (temperature / spinner /
capacitance etc)
4) Cement bond log
5) Noise logs
6) Pressure build-up tests
7) Tracer testing
8) Downhole video camera
9) 4-D seismic result

ATTHE END OFTHE DIAGNOSISWORKTHE ENGINEER WILL COME
UPWITH A CLEAR PICTURE OF RESERVOIR FLUID MOVEMENT
PATTERN AND ITS FLOW INTOTHEWELLBORE.

OBJECTIVE OFWATER SHUTOFF
TREATMENTS
 Objective is to shut off water without seriously damaging
hydrocarbon productive zones.
 Want to maximize blocking agent penetration into water-source
pathways, while minimizing penetration into hydrocarbon
zones.
 Want to maximize permeability reduction in water-source
pathways, while minimizing permeability reduction in
hydrocarbon zones.

WATER CONTROL SOLUTIONS
Mechanical Solutions
Physical Solutions
Chemical Solutions

WATER CONTROL SOLUTIONS
Mechanical Solutions & Well Techniques
 Packers
 Bridge Plugs
 Casing Patches
 Infill Drilling
 Side Tracking
 Horizontal
 Multilateral
 Pattern Flow Control

POSISET MECHANICAL PLUGBACKTOOLAPPLICATION.THE POSISETTHROUGH-TUBING PLUG IS
USED FOR NEAR-WELLBOREWATER SHUTOFF.THEWIRELINE-OR COILEDTUBING-DEPLOYED
PLUG USESA POSITIVE ANCHORING SYSTEMWITH UPPERAND LOWER SLIPANCHORS (TOP)THAT
ISOLATEWATER-PRODUCING LAYERS IN BOTH OPENANDCASED HOLES (BOTTOM).
 Mechanical solutions—In many nearwellbore problems, such as
casing leaks, flow behind casing, rising bottom water and
wateredout layers without crossflow, mechanical or inflatable
plugs are often the solution of choice.The PosiSet mechanical
plugback tool can be deployed on coiled tubing or wireline, and
is a field-proven technology that ensures reliable wellbore
shutoff in cased- and openhole environments (right).

CASING PATCHES
 >The PatchFlex sleeve. A flexible composite cylinder made of
carbon fiber, thermosetting resins and a rubber skin, the
PatchFlex sleeve is built around an inflatable setting element
that is attached to a running tool and run into a well on a
wireline. When the sleeve is positioned opposite the area to be
treated, a pump within the running tool inflates the sleeve using
well fluid.The resins are then heated until fully polymerized.The
inflatable setting element is then deflated and extracted to
leave a hard, pressure-resistant sleeve that fits snugly, even in
damaged or corroded casing.

PHYSICAL PLUGGING AGENTS
 Conventional Cement Squeeze
 Ultra Fine Cement
 Foam-cement
 Sand Plug
 Particulates

CONVENTIONAL CEMENT SQUEEZE
Often performs well as a blocking agent
Near wellbore application
Long life
Provide Mechanical strength to Polymer gel
Economical
Poor penetration

ULTRA-FINE CEMENT
Size - < 10 micron
Fine Sand and Micro-channels
Can be mixed with ultra fine silica
Thermal stability
Better penetrability than conventional cement
Expensive

HYDROCARBON BASED ULTRA-FINE CEMENT
Reacts slowly upon contact with water
(Oil producing Section Remains Undamaged)
Can be used in conjunction with polymer gel
Moderate penetration depth

FOAM CEMENT
Penetrates Deeper than Conventional Cement
Can be used in conjunction with polymer gel
(Improves Stability, viscocity, Structure of
Foam)
Relatively complex technology
Cement
Surfactant
as Stabilizer
N2 Gas
More Important in Gas Conformance Control

SAND PLUG
Rig-less alternative to conventional cement plugs(Injected By
CoiledTubing)
20/40 mesh sand + 100 mesh sand + Binder(eg. Alcoflood 935
polymer ) = Sand Plug Slurry
Penetration Depends on the Size of Sand
Inexpensive

PARTICULATES
- AS A SUBSTITUTE TO SAND
-Clay gels
-Carbonates
-Various Loss Control Materials

DISADVANTAGE
- Do not penetrate Deep.
- Forms poor pipe-formation seal.

WHY CHEMICAL OPTIONS ?
1. Sealing Matrix and Small Fissures.
 Mechanical means like tubing patch, casing patch, bridge plug,
straddle packer, scab liner, cement squeeze can provide a seal in
the well hardware and in large near-wellbore openings only.
 However, there are cases where it is desirable to achieve matrix
or small fissure penetration of the sealing material. Examples
include:
 (a) small cement channels/fissures
 (b) natural fractures
 (c) vertical coning through matrix.
Cement squeezes can’t solve these problems.

2.SELECTIVE REDUCTION OF
UNWANTED PHASE FLOW.
 A relative permeability modifier (RPM) can be pumped without
zonal isolation which reduces water permeability much more
than oil permeability.

3. SUBSEQUENT DEEPER ZONE
PERFORATING (TO AVOID CEMENT
UNDER-REAMING).
 A depleted zone must be sealed off prior to adding perforations
in a zone below the depleted zone.
 One option is to use a cement squeeze and then drill-out or
under-ream hardened cement in the casing in order to access
the target zone. However, this operation can be expensive.
 Alternately It may be possible to use a chemical to seal off the
depleted zone.Then the chemical can be washed out from the
wellbore quite easily in most of the cases, at a relatively lower
cost.

4. RESERVOIR CONFORMANCE.
In case of reservoir flooding, sometimes mobility control or
blocking highly permeable flow paths is beneficial, which requires
chemical means.

CHEMICAL WATER/GAS SHUTOFF
OPTIONS.
 1. Monomer Systems
 2.Polymer Systems
 3. Relative permeability modifiers(RPM)
 4. Resins

MONOMER SYSTEMS
 These are water thin solutions of monomer that
polymerize after placement to form gels.
 Temperature Activated free-radical initiated process that
occurs very rapidly once initiated.
 Therefore, gelation control is an issue.

 Properties
(a) Ideally they are nonreactive towards formation fluids.
(b)Water soluble. (Easy to Mix)
(c) Because of their low viscosity, theoretically, they are good for deep
matrix placement.
(d) It is stable in temperatures up to 275/300°F.
In high temperature reservoirs, sea water is pumped ahead of the
treatment to cool down the formation in near wellbore area.
(f)The resulting gel is quite strong and claims permeability reduction of
up to 99.7%.
MONOMER SYSTEMS

 Disadvantages.
It’s expensive.
Lower concentration systems are slightly water soluble and have
lower gel strength.
MONOMER SYSTEMS

CROSS-LINKED POLYMER SYSTEMS
 Polymer gel systems start as a
flowing mixture of two
components - high molecular
weight polymer and another
chemical called a cross-linker.
 At some trigger, the cross linking
molecules start attaching
themselves to two polymer
molecules.
 The result is a three dimensional
tangle of interconnected polymer
molecules (i.e. cross-linked) that
ceases behaving like a fluid and can
eventually constitute a rigid,
immobile gel.

Properties
 Variable concentration
 Low to very high viscosity
 Designable placement time
 Applicable in sand stone & carbonate
 Large volume application possible
 Applicable upto 140 0C
 Total sealant

Application :
 Bottom water shutoff
 Coning
 Channel from Injector
 Casing leak
 Fracture into injector/aquifer
 Plugging operation/zone abandonment
 Gas shutoff

 Smart or selective fluids (polymers and surfactants) are being
developed , which produce a permanent gel-like material to stop
flow in water layers, but retain fluid behavior in oil layers to
allow production to continue.
 It can simply applied using a low-cost bullheading method of
placement.
RELATIVE PERMEABILITY MODIFIER (RPM)

RPM system is based on a hydrophobically
modified water soluble polymer(HRPM) that, once
absorbed to the surface of the rock, selectively
reduces water effective permeability with little to
no damage to oil or gas production.
Commonly used RPM,
Xantham co-polymer (XC)
Inorganic cross-linker

Properties
 Low to very high viscosity
 Shear thinning
 Applicable in sand stone
 Large volume application possible
 Applicable upto 100 0C
 Designable gel strength

Relative permeability Modifier (RPM)
Properties cont.…
 Bull head treatment possible
 Needs mechanical support
 Low cost
 Applicable in 3-D conning &
unpredictable watered out zone

RESINS
 Resins are formulated and partially reacted before shipment to
the field.
 A catalyst, added before pumping, causes the liquid plastic to
react at bottomhole temperature.
 The catalyst may be an acid or a base, depending upon Resins
used(phenolic, epoxy and furfuryl alcohol resins).
 Bottomhole temperature and pumping time must be known to
prevent polymerization from occurring too soon or taking too
long after placement.
Water Control Materials

Resins system Characteristics
Properties
 2 or 3 component system
 Low viscosity
 Permanent solution
 Irretrievable
RESINS

Properties
 Provides sufficient strength to block fluid movement in pores,
fractures, vugs , channels ,Casing Leaks and perforations.
 They are inert to all common downhole conditions and fluids
and provide complete, long-term sealing of passages, if properly
placed.
 They are relatively expensive.Therefore their use normally is
confined to within the first radial foot of a wellbore.
RESINS

EXCESSWATER PRODUCTION PROBLEMS AND
TREATMENT CATEGORIES
Category A: "Conventional"Treatments are Normally an Effective Choice
 Casing leaks without flow restrictions (medium to large holes).
 Flow behind pipe without flow restrictions (no primary cement).
 Unfractured wells (injectors or producers) with effective barriers to crossflow.
Category B:Treatments with Gelants are Normally an Effective Choice
 Casing leaks with flow restrictions (pinhole leaks).
 Flow behind pipe with flow restrictions (narrow channels).
 "Two-dimensional coning" through a hydraulic fracture from an aquifer.
 Natural fracture system leading to an aquifer.

EXCESSWATER PRODUCTION PROBLEMS AND
TREATMENT CATEGORIES
Category C:Treatments with Preformed Gels are an Effective Choice
 Faults or fractures crossing a deviated or horizontal well.
 Single fracture causing channeling between wells.
 Natural fracture system allowing channeling between wells.
Category D: Difficult Problems for which GelTreatments Should Not Be Used
 Three-dimensional coning.
 Cusping.
 Channeling through strata (no fractures), with crossflow.

PLACEMENT STRATEGIES
Coning
Crossflow
BreakthroughRise of OWC
FractureChanneling
Casing Leak

SIMPLE RIG UP EXAMPLE
Bull-Heading

WHY DO ADSORBED POLYMERS AND
WEAK GELS SHOW LARGE
PERFORMANCEVARIATIONS?
• Mineralogy varies within rock, so the level of
adsorption also varies.
• Particle suspensions (e.g., weak gels) often
have uncontrolled size distributions.
• Pore size distributions vary in rock.

WHY DO GELS REDUCE KW MORE
THAN KO?
• Even with low pressure gradients, oil forces
pathways through by destroying or
dehydrating the gel. In contrast Water may
help in hydration of gel.
•These oil pathways allow ko to be much
higher than kw.
• Even so, ko is lower than before gel
placement.

Water control

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