1-压裂液的分类及性能评价方法

• Mix Gel and Chemicals Consistently • Test Fluid at Realistic Temperature, Time • •
and Shear Rate Test Gel Using Correct Shear Rate History Do Multiple Tests to Ensure Repeatability
Linear Gel
Crosslinked
0.8
0.5
0.03
0.55
50
2000
MEASUREMENTS OF APPARENT VISCOSITY
• Use Actual Samples of Mix Water and
Chemicals That Will Be used on the Treatment
Where: a = Apparent Viscosity, cp k’ = Consistency Index, lb-secn ’ 2 / ft a n’ = Flow Behavior Index, Dimensionless = Shear Rate, sec-1
TYPICAL SHEAR RATES DURING FRACTURING
Cw
m A
0.0164m (Measured in Lab) A
= Slope of Volume vs t Graph = Area of Core Used to Measure Cw
MEASUREMENT OF WALL BUILDING COEFFICIENT (C w )
Slope = C w * Area / 0.0164
1) Compatible With the Formation Rock and Fluids 2) Generating Adequate Fracture Width to Accept the Proppant 3) Capable of Suspending Proppants and Transporting Them Deep into the Fracture 4) Maintain Viscosity During the Treatment and “Break” Afterwards 5) Cost Effective
VOLUME
Spurt Loss
TIME
EFFECT OF FLUID LOSS ADDITIVES (FLA) ON WALL-BUILDING FLUID-LOSS COEFFICIENT, C w
.
)
1/2
0.008
FLUID LOSS COEFFICIENT, C w (ft/min
Titanate Fluid
VISCOSITY AT A KNOWN SHEAR RATE
• To Calculate the Apparent Viscosity of a
Non-Newtonian Fluid, the Following Equation is Used
a 47880 k’ a
[]
n’- 1
2
k‘ = Intercept
LOG-SHEAR RATE ( )
MODELING OF FOAMS
o k n
= Shear Stress, lb/ft 2 o = Yield Point, lb/ft 2 k = Foam Consistency Index, lb-secn/ft2
Foam Base or Energized Fluids
Oil Based Fluids
Gelled Oil Cross-linked Oil Oil-in-water Emulsion Gelled Acid Cross-linked Acid Foamed Acid
1/ 2
k C Cc 0.0374p r r r
kr Cr r
1/2
= Permeability to Reservoir Fluid, md = Formation Fluid Compressibility, psi -1 = Formation Fluid Viscosity, cp
FRACTURING FLUIDS
OUTLINE
• Introduction • Fluid Mechanics • Types of Fracture Fluids • Fracture Fluid Additives • Selection of a Fracture Fluid
REQUIREMENTS OF A FRACTURING FLUID
n’ 1
= Apparent Viscosity, cp = Consistency Index, lb-secn’/ft 2 = Flow Behavior Index, Dimensionless
Q w h
= Injection Rate, bpm = Fracture Width, in = Fracture Height, ft
FRACTURING FLUIDS ARE TYPICALLY DESCRIBED WITH POWER LAW MODEL
= k’n’
LOG-SHEAR STRESS ( n’= Slope = Shear Stress, lb/ft = Shear Rate, sec-1 k = Consistency Index, lb-secn /ft 2 n = Flow Behavior Index, dimensionless
n= Foam Flow Behavior Index, dimensionless
Foamed Fluids Are Modeled Using a Modified Power Law Equation kand n Are Used to Describe the Foam Along With a Yield Point, o
VISCOSITY MEASUREMENTS
Torsion Spring
ROTATING CUP
STATIONARY BOB
TEST FLUID
TYPICAL VISCOSITY VALUES
Fluid Type Water n’ 1.0 k’ 0.00002 Viscosity @ 170 sec -1 1.0
• Shear Rates in Tubular: 100 - 5000 sec-1 • Shear Rates in Fractures: 10 - 100 sec -1 • Measurements of n’ and k’ Often Made
•
Between 170 and 600 sec -1 May Not Be Representative of the Fluid Behavior in the Fracture (40 sec -1)
Ct
1 1 1 1 Cv Cc Cw
• William’s Method
Ct C vC w

2 C cC v C w 4C 2 c
2 C2 Cr w

C2 v

C2 w

1/2
EFFECT OF FLUID EFFICIENCY
LOW FLUID EFFICIENCY
Short Fracture
WHAT IS VISCOSITY?
p or Shear Stress Newtonian Fluid p Constant = Q for Newtonian Fluid
Q or Shear Rate ()
Q Q
p
RELATIONSHIP OF AND FOR DIFFERENT FLUID TYPE MODELS
FLUID MECHANICS
PROPERTIES OF A FRACTURE FLUID
•
•
• •
•
Viscosity - Controls Fracture Width (Near Wellbore) - Impacts Proppant Transport Fluid Loss - Controls Amount of Fluid in Fracture - Impacts Fracture Geometry Density - Controls Hydrostatic Gradients - Impacts Proppant Convection Friction - Controls Surface Treating Pressure - Impacts Injection Rate pH - Controls Crosslinker Reactions - Impacts Fluid Properties
Affecting Proppant Placement
-
Convection Settling
TYPES OF FRACTURE FLUIDS
FRACTURE FLUID TYPES • Water Based Fluids •
• •
Linear Gel Fluids Cross-linked Gel Fluids N 2 , CO 2 ,Or Both Water, Acid, Oil
High Filtration
HIGH FLUID EFFICIENCY
Longer Fracture
Low Filtration
FLUID EFFICIENCY
• Percentage of Fluid in the Fracture • Affects Created Fracture Dimensions • High Leakoff Can Lead to Screenouts • Low Leakoff Will Increase Closure Time