acid placement and diversion
TRANSCRIPT
1
Acid Placement and Diversion Behzad Hosseinzadeh
Spring 2015 Number of slides : 33Supervisor: Dr. Aghighi
2
IntroductionAcidization
Introduction
Objectives
Methods
MAPDIR
Mechanical
Chemical
Protective
Acid Fracturing
In-situ
Summarizes
3
IntroductionSandStone Vs. Carbonate
SandStone
Carbonate
Introduction
Objectives
Methods
MAPDIR
Mechanical
Chemical
Protective
Acid Fracturing
In-situ
Summarizes
4
IntroductionTwo Reason Why Acid Treatments Fail
Acid-removable damage is not presentIf it is present it is not fully contacted
o Acid does not go where it needs to go
Before acid treatment After acid treatment (without diverter)
Introduction
Objectives
Methods
MAPDIR
Mechanical
Chemical
Protective
Acid Fracturing
In-situ
Summarizes
5
IntroductionDiverting
Introduction
Objectives
Methods
MAPDIR
Mechanical
Chemical
Protective
Acid Fracturing
In-situ
Summarizes
6
Acid PlacementObjectives of Acid Placement and Diversion
1. Coverage of the production or injection interval(s) targeted for acid treatment
2. Distribution (spread) of the acid treatment in the formation.
Introduction
Objectives
Methods
MAPDIR
Mechanical
Chemical
Protective
Acid Fracturing
In-situ
Summarizes
7
Acid Placement, In The WellBoreMethods
1. Bullhead injection (MAPDIR Method)
2. Mechanical placement3. Chemical diversion4. Protective Injection
Maximize Coverage … Minimize Volumes
Introduction
Objectives
Methods
MAPDIR
Mechanical
Chemical
Protective
Acid Fracturing
In-situ
Summarizes
8
MethodsThe MAPDIR Technique
• maximum pressure differential and injection rate• This was first introduced by Paccaloni and Tambi • Referred to as Paccaloni’s method• limited zone height, length and permeability variation• Openhole, or liner completions in single or multiple
zones, as well as in thin zones
Introduction
Objectives
Methods
MAPDIR
Mechanical
Chemical
Protective
Acid Fracturing
In-situ
Summarizes
9
Mechanical MethodsPacker / Bridge Plug.
• The surest way to place fluid• Earliest mechanical method• Retrievable and Permanent• Types
• Cup type packers• Mechanical packers• Inflatable packers
• Expensive• Need kind of intervention,
such as a workover
Introduction
Objectives
Methods
MAPDIR
Mechanical
Chemical
Protective
Acid Fracturing
In-situ
Summarizes
10
Mechanical MethodsBall Sealers
• Most widely used• More economic• Overcome drag forces• Suitable for high
permeability contrast• Efficiently in vertical
wells. • larger than perforation• Rubber or Biopolymer
Introduction
Objectives
Methods
MAPDIR
Mechanical
Chemical
Protective
Acid Fracturing
In-situ
Summarizes
11
Mechanical MethodsBall Sealers
• Type• Sinkers (non-buoyant balls) • Floaters (buoyant balls) • Neutral buoyant
Floaters
Neutral
Sinkers
Introduction
Objectives
Methods
MAPDIR
Mechanical
Chemical
Protective
Acid Fracturing
In-situ
Summarizes
12
Mechanical MethodsJetting
• The acid can be placed directly at the point where it is needed.
• Ease with which an acid injection can be terminated
• Most completions• With foam provides
excellent zone coverage• Rotary action required
• For perforation coverage• For screen or open hole coverage
Introduction
Objectives
Methods
MAPDIR
Mechanical
Chemical
Protective
Acid Fracturing
In-situ
Summarizes
13
Chemical MethodsChemical Diversion
Introduction
Objectives
Methods
MAPDIR
Mechanical
Chemical
Protective
Acid Fracturing
In-situ
Summarizes
14
Chemical MethodsChemical Diversion
• The more commonly used chemical diverters today include:
1. Salt granules• Low solubility in strong acid but soluble
in formation water• Not be used in a formation that does
not produce water• Combined particulates, such as
graded rock salt and benzoic acid
• Work best in perforated casingand with medium permeability contrast.
Introduction
Objectives
Methods
MAPDIR
Mechanical
Chemical
Protective
Acid Fracturing
In-situ
Summarizes
15
Chemical MethodsChemical Diversion
2. Benzoic acid• The most broadly applicable diverter type• Has limited solubility in both oil and water• It has the ability to sublime directly into its gaseous state,
above about +/- 230 °F.• Benzoic acid particulates are typically added to water or acid-
based carrier fluids (a surfactant may be required for dispersal)
• Removal is either by slow dissolution in produced oil (preferred) or water, or through sublimation at higher temperatures.
Introduction
Objectives
Methods
MAPDIR
Mechanical
Chemical
Protective
Acid Fracturing
In-situ
Summarizes
16
Chemical MethodsChemical Diversion
3. Waxes• These materials are usually removed from the well by either
the action of temperature, dissolution in liquid hydrocarbons or both.
4. Oil-soluble resins (OSR) • Are not as popular today as they used to be
5. Gilsonite• Naturally-occurring asphalt material
6. Fiber• Effective diverting agents for both matrix and fracture
treatments
Introduction
Objectives
Methods
MAPDIR
Mechanical
Chemical
Protective
Acid Fracturing
In-situ
Summarizes
17
Chemical MethodsChemical Diversion
6. Foam• It is useful in gravel pack completions
7. Viscous pills• Polymer gels, such as hydroxyethylcellulose (HEC)• Which can provide sufficient diversion• Remaining gel residue in perforations can block flow.• A separate treatment may have to be conducted to remove
the gel.
The major benefit of foams and gels relative to particulates is their reversibility.
Introduction
Objectives
Methods
MAPDIR
Mechanical
Chemical
Protective
Acid Fracturing
In-situ
Summarizes
18
Chemical MethodsChemical Diversion
Introduction
Objectives
Methods
MAPDIR
Mechanical
Chemical
Protective
Acid Fracturing
In-situ
Summarizes
19
Diversion MethodsProtective Injection
Introduction
Objectives
Methods
MAPDIR
Mechanical
Chemical
Protective
Acid Fracturing
In-situ
Summarizes
20
Diversion MethodsAcid Fracturing Treatments
• Many of the techniques described in the preceding sections also can be applied to acid-fracturing operations.
• Mechanical isolation methods work particularly well, although this often involves extra expense, such as for a workover or for specialized completions.
• This often is accomplished with the use of diversion stages programmed into the treatment schedule, effectively breaking up a large treatment into several smaller ones.
Introduction
Objectives
Methods
MAPDIR
Mechanical
Chemical
Protective
Acid Fracturing
In-situ
Summarizes
21
Acid Diversion in the FormationIn-situ diversion
• In-situ diversion is also necessary and quite important in both matrix and fracture acid treatments.
Introduction
Objectives
Methods
MAPDIR
Mechanical
Chemical
Protective
Acid Fracturing
In-situ
Summarizes
22
Acid Diversion in the FormationFoam
• Foam is a two-phase, gas-in-liquid emulsion consisting of a liquid external phase and a gaseous internal phase.
• They observed that successful diversion can be expected for permeability ratios less than 10:1.
• A surfactant is required to keep the foam stable until it enters the formation.
• Work better in higher-permeability formations.• Oil tends to destroy foams
Introduction
Objectives
Methods
MAPDIR
Mechanical
Chemical
Protective
Acid Fracturing
In-situ
Summarizes
23
Acid Diversion in the FormationFoam
Introduction
Objectives
Methods
MAPDIR
Mechanical
Chemical
Protective
Acid Fracturing
In-situ
Summarizes
24
Acid Diversion in the FormationFoam
Introduction
Objectives
Methods
MAPDIR
Mechanical
Chemical
Protective
Acid Fracturing
In-situ
Summarizes
25
Acid Diversion in the FormationSelf-Viscosifying Acids (SVA)
• Has three specific components:1. Gelling agent2. Crosslinking agent (Fe, Al, Zr)3. Breaker
• no H2S and permeability greater than 50 md.
Introduction
Objectives
Methods
MAPDIR
Mechanical
Chemical
Protective
Acid Fracturing
In-situ
Summarizes
26
Acid Diversion in the FormationSelf-Viscosifying Acids (SVA)
Introduction
Objectives
Methods
MAPDIR
Mechanical
Chemical
Protective
Acid Fracturing
In-situ
Summarizes
Live partially neutralized, spent acid
27
Acid Diversion in the FormationSelf-Viscosifying Acids (SVA)
Introduction
Objectives
Methods
MAPDIR
Mechanical
Chemical
Protective
Acid Fracturing
In-situ
Summarizes
28
Acid Diversion in the FormationViscoelastic surfactant systems (VES)
• VES systems designed for matrix or acid fracturing operations exhibit viscosity as a function of acid strength
Introduction
Objectives
Methods
MAPDIR
Mechanical
Chemical
Protective
Acid Fracturing
In-situ
Summarizes
29
Acid Diversion in the FormationViscoelastic surfactant systems (VES)
Introduction
Objectives
Methods
MAPDIR
Mechanical
Chemical
Protective
Acid Fracturing
In-situ
Summarizes
30
Acid Diversion in the FormationComparing VES - SVA
• Why do we use VES instead of SVA?1. No residue 2. Completion brines3. No damage
Introduction
Objectives
Methods
MAPDIR
Mechanical
Chemical
Protective
Acid Fracturing
In-situ
Summarizes
31
Acid Diversion in the FormationViscous Fingering
Relies on viscosity contrast between acid and non-acid fluidsIntroduction
Objectives
Methods
MAPDIR
Mechanical
Chemical
Protective
Acid Fracturing
In-situ
Summarizes
32
Acid Diversion Summarizes
Introduction
Objectives
Methods
MAPDIR
Mechanical
Chemical
Protective
Acid Fracturing
In-situ
Summarizes
33
References
1. L.J. Kalfayan, The Art and Practice of Acid Placement and Diversion: History, Present State and Future, 2009
2. Ragi Poyyara, Optimization of Acid Treatments by Assessing Diversion Strategies in Carbonate and Sandstone Formations , 2014
3. Leonard J. Kalfayan, The Art and Practice of Acid Placement and Diversion, 2005
4. Leonard Kalfayan, Production enhancement with acid stimulation, 2nd ed, 2007
5. Javier Ballinas, Weatherfird, Viscous Fingering Stimulation Option Applied on Heavy-Oil Carbonate Reservoirs, 2014
6. M.G. Bernadlner, Effect of Foams Used During Carbonate Acidizing, 19927. Liang Jin, Optimising Diversion and Pumping Rate To Effectively Stimulate Long
Horizontal Carbonate Gas Wells, 20078. G. Glasbergen, Design and Field Testing of a Truly Novel Diverting Agent , 2006