Transcript No Slide Title

Preliminary Review:
- Soft Sand Completion Practices
A Preliminary Review of Completion Practices in
Soft (Unconsolidated) Sandstone Formations
- Public Domain and JIP Information
Bjarni Palsson, Stavros Kastrinakis
General Items for Discussion
 General Completion Options for Water Injectors
 Completion Guidelines for Water Injectors
 Morita et al., paper SPE 39436
 Objective: Best Practices Document
Completion Methods for Water
Injection Wells (General)
 Gravel / frac-packing
 Open hole with a screen or a pre-packed screen
 Cemented + perforated casing/liner with a
propped hydraulic or thermally induced fracture
 Selective perforation
 Open hole (barefoot)
Soft Sand Completion Issues
What is a Soft Sand (Definition)
Formation Failure Mechanism
Completion Design Criteria
Completion Field Experience
What is Soft Sand? (Definition)
Screening criteria (Tony Settari):
Low unconfined compressive stress (UCS)
Low Young’s modulus (E)
Poro-plastic compressive behaviour (low cohesion)
Poor core integrity and wash-out during lab tests
Sand production and wellbore stability problems
Stress dependent porosity and permeability
Stress Path (Heriot-Watt)
Completion Failure in Soft Sand Wells
Perforation cavity or wellbore collapse
Hardware damage
Erosion and corrosion (during installation and
operation)
Compaction (well collapse)
Screen plugging
Sand production
Oil and solids in injection water
Formation Failure in Soft Sand Wells
Perforation Cavity Collapse
Caused by:
Rock mechanical failure (changes in total stress and
differential stress)
Chemical unstability (cementation, capillary pressure)
Due to:
Backflow as a stimulation treatment
Crossflow during well shut-in (layered sands)
Pressure disturbance as a result of well shut-in (water
hammer effect)
Formation Failure in Soft Sand Wells
 Results in injectivity decline due to sand filled
perforations
Morita et al. (SPE 39436): In high permeable
sand, permeability of sand filled perforations can
be much lower than the initial permeability
Up to 70% of the injection pressure drop (Pwf-Pe)
occurs within the sand filled perforations
 Sand filled perforations may be more prone to
plug by solids in the injection water
Design Criteria for Injection Well Completion
 In general, same rules as
for production wells
Injection well BHFP
Injection well:
Pressure charging
 Difference:
 Near wellbore area of
injection wells is pressure
charged
 Injection wells have to
withstand solids flow in
two directions
Reservoir pressure
Production well:
Pressure drawdown
r
Production well BHFP
r
Field Experience
Public Domain Literature
PWRI JIP Information
BP Amoco: BP-1, BP-2, BP-3, BP-4, BP-5
Norsk Hydro: NH-1
PanCanadian Petroleum: Countess field
Statoil: Heidrun field, Snorre field
Unconsolidated - not necessarily soft sand!
Either fulfill “screening criteria” or
(Very) high permeability
Formation Failure after well Shut-in
(Water Hammer Effect)
Statoil: Heidrun Field
(PWRI JIP)
Highly unconsolidated formation
Injection wells completed without sand control
Sharp injectivity decline linked to emergency shut-ins
“Liquefied” sand believed to fill the wellbore above
perforations
Possible remedial actions
Sand control
Eliminate water hammer effects
Formation Failure after well Shut-in
(Water Hammer Effect)
Petrobras: Marlim Field (SPE 53789)
Production wells and horizontal injection wells
completed with sand screens
Deviated injection wells without sand control
Sand production associated with shut-ins (WHE)
“Solved” with retainer valves above perforations
Performance of Pre-Packed Screens
Successful applications
BP Amoco: Harding Field (SPE 48977)
Petrobras: Marlim (SPE 53789)
BP-3 and BP-4 (PWRI JIP)
Sun Oil Britain: Balmoral field (SPE)
Wilmington field, California
(SPE 1543)
Pre-packed screens the best sand control
But still sand production - Gravel size too high?
Comparison between Production Well and
Injection Well Completion Strategies
BP Amoco: Forties Field
(SPE 6677)
Initially both producers and injectors cemented
and perforated but no sand control
Production wells had no sand production problems
But sand production in some of the injectors
Sun Oil Britain: Balmoral Field
Similar formation as Forties ??
Both producers and injectors (successfully) gravel
packed
Issues for Discussion
 Water Hammer Effects (WHE)
How and when do water hammer effects occur?
 Retainer valves
Can installation of retainer valves above perforations
stop water hammer effects?
 Injectors versus producers
Why Forties injectors have more sand production
problems than the producers?
 Corrosion and erosion problems
Need for corrosion protection in injection well
completions and risk of debris plugging?
Issues for Discussion
 Innovative solutions
Mechanical profile control with mandrels in water
injection wells; Needham et al. (SPE 54746)
Single Trip Perforating and Gravel Pack System
(STPP); Jones (SPE 54285)
Low cost formation consolidation with steam injection
in the Wilmington field; Davies et al. (SPE 38793)
 Guidelines for solving sand problems in water
injection wells
Morita et al. (SPE 39436)
Issues for Discussion
Measurements of completion efficiency
Q, THP, II or Skin
Permeability-adjusted skin
40
Skin factor
35
Pahmiyer et al. (SPE 54742):
30
Trend line relationship
between permeability and
skin
25
20
15
10
Frac-pack trendline
5
HRWP
0
0
500
1000
1500
2000
Permeability (md)
2500
3000