Sand Control Fundamentals & Design D. Koukhani / A. Hooshmand /34 HOW SANDING OCCURS In most sandstone reservoirs sanding occurs in two stages: • First, the.

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Sand Control
Fundamentals & Design
D. Koukhani / A. Hooshmand
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HOW SANDING OCCURS
In most sandstone reservoirs sanding occurs in two stages:
• First, the rock fails mechanically in the near wellbore
area because of changes in and redistribution of the
stresses as the bore is drilled or produced. Mechanical
failure does not necessarily mean immediate sand
production.
• Then after the rock has failed, viscous drag forces
generated by the flow of production fluids erode the
failed material into the wellbore and up the flow path to
surface.
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Main Geological Characteristics of
Sandstone Reservoirs
Sandstone minerals can be split into three main
groups:
• Detrital residue
• Secondary detrital residue
• Chemical precipitates
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Main Geological Characteristics of
Sandstone Reservoirs
Sandstone minerals:
• Detrital residue:
Contain minerals from a source rock that have
been transported and deposited mechanically,
with quartz and feldspar typical of this group.
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Main Geological Characteristics of
Sandstone Reservoirs
Sandstone minerals:
• Detrital residue
• Secondary detrital residue:
Clays are representative of secondary detrital
minerals that have also been transported and
deposited mechanically.
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Main Geological Characteristics of
Sandstone Reservoirs
Sandstone minerals:
• Detrital residue
• Secondary detrital residue
• Chemical precipitates:
Minerals deposited from solution by chemical or
biochemical processes.
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Main Geological Characteristics of
Sandstone Reservoirs
1. Quartz:
Concentration range of 50 – 70% can form up to
99% of the rock.
2. Feldspar:
Concentrations of up to 12%, the next most
common sandstone minerals after quartz.
3. Heavy mineral
4. Cementing material
5. Other
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Formation of Sandstones
Sandstones, like all sedimentary rocks are produced by a
combination of
• Weathering of existing rocks (igneous, metamorphic and
sedimentary-older sedimentary).
• Transport and erosion of the weathered material and
diagenesis.
Weathering results in the breakdown of the existing rock
into smaller particles. These are then moved by wind,
water, gravity or a combination of the three.
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Classification of Sandstones
Sandstones have been classified by various criteria such
as particle size or shape, sorting, mineralogy of the grains
or of the cementations material etc.
One common method uses the following classification by
mineral content:
• Arkoses
• Greensands
• Greywackes
Sandstones are also classified by their grain size:
• Coarse Grained Sandstone.
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Particle Size Measurement
Wentworth scale is used to measure grain size:
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Particle Size Measurement
Methods:
There are two common methods used for determining the
particle size distribution of a sedimentary rock:
• Sieving
• Laser Diffraction
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Particle Size Measurement
Sieving
Advantages:
• Cheap & Usable
Key Disadvantages:
• Not possible to measure sprays or emulsions
• Measurement for dry powders under 38 microns very difficult
• Clays difficult to measure
• Not high resolution
• Particles not very well dispersed
• Needs at least 20g
• Does not measure below 45 microns
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Particle Size Measurement
Laser Diffraction
Advantages:
• Flexibility
• Dry powders can be measured directly
• Liquid suspensions and emulsions can be measured
• Entire sample is measured
• Quicker than sieving
• Sample size depends on particle size but typically <1g
• Measures average diameter of particles
• High resolution
Key Disadvantages:
• Equipment is expensive – specialist test facilities required.
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Comparison between
LDS & Sieve Analysis
The four main parameters utilized from the grain size distribution analysis
are D10, D40, D50 and D90.
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Sampling Methods
There are two fundamental methods of sampling sandstone
reservoirs – downhole coring and surface sampling. These
can be subdivided into:
• Rotary coring
• Sidewall coring
• Bailing
• Surface sampling of circulated or produced material
Samples can be obtained from:
• Cores
• Drill Cuttings
• Junk Baskets
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Sand Face Completion
The choice of equipment which is run across the formation
interval forms the sand face completion.
The selection will be based on whether the well is
• Open hole or cased and perforated,
• Vertical, deviated or horizontal,
and
• Expected production conditions
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Sand Face Completion
Choices of completions for sand control across the
formation face:
•
•
•
•
•
•
Screens
Frac-Pack
Gravel Pack
ESS / CHESS
Slotted Liner
Chemical Considerations
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Screens
Different types of screens that use a different filtering media
exists:
• Wire-wrapped screens
Have a base pipe with slots or holes around the circumference that is either
single-wire wrapped or surrounded by cylindrical sieves of various mesh sizes.
• Pre-packed screens
Employ a different filtering media. A layer of consolidated resin coated gravel is
placed around the internal screen assembly and is supported by a shroud or
external screen.
• Premium screens
Premium screens are typically an all-metal design, with a metal mesh filtration
media and a protective outer metal shroud.
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Wire Wrapped Screen
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Pre-Packed Screen
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Premium Screen
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Frac-Pack
• Frac-pack is a sand control method by which a propped
hydraulic fracture of limited length is created into a weak
or unconsolidated reservoir.
• Wells producing from unconsolidated reservoirs using
frac-packs require lower drawdown pressures to
produce.
• The main reasons for using frac-packing as a sand
control technique are:
–
–
–
–
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By passing formation damage
Reduce water coning
Controlling sand production
Enhance productivity in low permeability formations
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Gravel Pack
In a gravel pack, the annulus between the wellbore and a
base perforated pipe with wirewrapped screen, is filled with
gravel.
Advantages
• Productivity impairment can be minimized by design
• Especially useful for heterogenous sands in long productive intervals
Disadvantages
• Complicated workovers
• Chemical compatibility of WBM and produced fluids
• Risk of incomplete gravel pack leading to premature screen failure
• Screen damage from erosion and corrosion is a major concern
• Chemical compatibility of OBM and carrier fluid
• Can be difficult to use in deviated and horizontal wells
• Flow control and isolation is complex
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Expandable Sand Screen (ESS)
• Unique approach to solve sand control problems.
• Large OD expanded to contact the wellbore stabilizes
formation.
• System designed to resist erosion and plugging.
• Large ID to maximize well intervention options.
• Large and uniform flow area to optimize production.
• Simple deployment minimizes operations costs.
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Slotted Liner
• tubing sections with a series of slots cut through the
walls in an axial orientation.
• The main limitation of slotted liners is their flow area – an
average of 3% and maximum of 6% is accepted.
• Flow areas of more than 6% are detrimental to the
tensile strength of the pipe.
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Slotted Liner
Common Slot Profiles
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Chemical Considerations
• Used in formations with little or no cementitious material.
• A major benefit is that the wellbore is left free of
obstructions.
• Fundamental principle =
bond the quartz grains together using a liquid resin.
• This will then provide an artificial cementing material
between the grains.
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Expandable Sand Screens (ESS)
Design & Construction
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ESS Design
1
EST Base Pipe
Slots open up
2
Woven Filter
Sheets slides over
one another
UNEXPANDED
3
Outer Shroud
Slots open up
Expandable
Base Pipe
Overlapping
Layers of
Filter Media
EXPANDED
Expandable
Outer
Protective
Shroud
No change in
weave aperture
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ESS Manufacture
3 LAYERS SANDWICHED TOGETHER
EST Base Pipe
1
Petroweave
2
Outer Shroud
3
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Axial Compliant Expansion Tool
Axial Compliant Expansion
Tool
The ACE Tool is run
after the fix cone for
Borehole contact.
1800 psi hydraulic actuation
Compliant Expansion speed 10ft/min
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Compliant Expansion Benefits
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Value of ESS - NISOC
Well #
AZ-156
AZ-149
AZ-91
MI-42
MI-12
Well Performance with IGP
WHP (psi) Rate (BBL/D)
Choke Salt (gr/m3)
1220
2,500
32/64
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1060
1,500
24/64
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1300
2,000
28/64
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850
1,500
24/64
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910
3,000
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Total Production = 10,500 bpd
Well #
AZ-156
AZ-149
AZ-91
MI-42
MI-12
Well Performance after Re-Completion with ESS
WHP (psi)
Rate (BBL/D)
Choke Salt (gr/m3) Sand Problem
1312
4,000
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NO
1210
3,000
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NO
1300
2,000
28/64
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NO
850
3,200
32/64
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NO
890
3,500
36/64
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NO
Total Production = 15,700 bpd
Increase with ESS Screens = 5,200 bpd = $208,000/day!!!
Project costs (excluding workover) recovered in 5 days
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