ENG101 FOAE - 08 Acid Design Fundamentals-Matrix Rev 2006-03-25
ENG101 FOAE - 08 Acid Design Fundamentals-Matrix Rev 2006-03-25
ENG101 FOAE - 08 Acid Design Fundamentals-Matrix Rev 2006-03-25
Matrix
Section 8
Printed: 3/25/2006
EDC, Tomball, TX
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EDC, Tomball, TX
1
Pore & Fracture Pressure
Constraints
O Matrix acidizing is injecting the acid into
the formation matrix below frac pressure
to achieve radial penetration into the
formation porosity (intergranular, vugular
or fracture porosity).
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EDC, Tomball, TX
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EDC, Tomball, TX
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Pore & Fracture Pressure
Constraints (cont.)
O Normally, matrix acidizing will not give
any significant stimulation to an
undamaged well in either a sandstone or
carbonate formation.
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EDC, Tomball, TX
“Wormhole”
EDC, Tomball, TX
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Sandstone Matrix Treatments
O Sandstone Acid History
O BJ’s Approach to Sandstone Acid
O Skin Removal
O Pumping Procedures
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EDC, Tomball, TX
Historical Breakthroughs
in Sandstone Acidizing
O 1933
³ First HF acid treatment in sandstone (King Royalty Co.,
TX)
³ Result: Prolific sand production
O 1939
³ Introduction of Mud Acid (12% HCl-3% HF)
O 1960s
³ Tapered acid treatments and organic acids introduced
³ Kinetics of HF reaction in sandstones
O 1984
³ McLeod Fluid Selection Guidelines
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EDC, Tomball, TX
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BJ Approach to
Sandstone Acidizing
O Mature field enhancement
O Remedial needs – including acid
O Field-wide approach
O Simplified & selective treatments
O Candidate wells previously avoided
³ Long vertical completions
³ Horizontal completions
³ Multiple zones
³ Open–hole completions
³ High temperature formations
³ High water cut wells
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EDC, Tomball, TX
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Standard Conventional
Sandstone Acidizing Procedure
1. Tubing pickling stage
6. Diverter stage
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EDC, Tomball, TX
Simplified
Ideal Sandstone Acidizing Procedure
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EDC, Tomball, TX
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Carbonate Matrix Treatments
O Design Factors
O Commonly Used Acids & Acid Systems
O Wormhole Patterns
O Pumping Procedure
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EDC, Tomball, TX
Design Factors
O Determine presence and type of damage
O Determine appropriate fluids and volumes
³ Determine Frac Gradient
³ Determine Max. Surface Treating Pressure and
Rate
O Determine proper treatment additives
O Determine proper placement technique
O Insure proper treatment execution and QC
O Evaluate the treatment results
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EDC, Tomball, TX
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Carbonate Formation
Composition
O Acid spends more rapidly in higher purity
carbonates
³ > 95% soluble
O Acid spends less rapidly in lower
solubility carbonates
³ ~ 65-85% soluble
³ Presence of relatively non-reactive siliceous
minerals
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EDC, Tomball, TX
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EDC, Tomball, TX
8
Acids Most Commonly Used
O Hydrochloric (HCl)
O Acetic (CH3COOH)
O Formic (HCOOH)
O HCl-acetic; HCl-formic
O Acetic-formic blends
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EDC, Tomball, TX
Concentration Guidelines
O Damaged perforations 9% formic
10% acetic
15% HCl
O Deep wellbore damage 15% HCl
20 - 28% HCl
HCl-organic blends
Formic-acetic
Viscous (retarded) acids
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EDC, Tomball, TX
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Acid Systems for Optimum
Wormhole Growth
O Achieved by reducing acid reaction
O Organic acids (acetic) - weaker than HCl
O Calcium-chelating agent (EDTA)
O Chemically retarded acid systems
(viscous)
O Viscous acids
O Dual-Phase acids
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EDC, Tomball, TX
Reservoir
Wormhole Patterns Stimulation
3rd Edition,
Economides
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Reservoir
Stimulation
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EDC, Tomball, TX
Pumping Procedure
O Pickling
O Preflush
O Treatment Acid
O Overflush
O Flush
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EDC, Tomball, TX
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Placement Techniques
O Mechanical Placement
³ Coiled tubing – RotoPulse / RotoJet tools
³ Selective acid and chemical treatment placement
³ Long, horizontal, and sand control completions,
injectors
³ Ball Sealers & Solid Particulate
O Chemical diversion
³ Foamed Acid
³ Divert S Acid systems – on-the-fly; self-diversion
³ Divert C surfactant gel stages
O ConformAcid treatments
³ Combined water control – acid stimulation
³ Relative permeability (RPM) options
³ Two-step and one-step treatment potential Slide 23
EDC, Tomball, TX
Section Summary
O Matrix Acidizing Design
³ Pore & fracture pressure constraints
³ Sandstone Matrix Acidizing
³ Carbonate Matrix Acidizing
³ Placement Techniques
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EDC, Tomball, TX
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