Design of High Performance Drilling Design of High Performance Drilling Fluids: Challenges And Future Directions for HP/HT Fluidsfor HP/HT Fluids
Apurva Samudra
Prof. Nick Sahinidis
Kickoff MeetingEnergy Systems Initiative (ESI) Energy Systems Initiative (ESI)
Center for Advanced Process Decision-making
Deep Drilling
o World energy demand continuously increasing
Total estimated conventional gas resources ato Total estimated conventional gas resources at depths > 4.5 km = 844 TCF
o No. of deep wells disproportionately small compared to their potential
Costs are an order of magnitude higher High costs limit the number of deep wells g p Drilling amounts to 50% of the total well costs Last 10‐20% of the bore hole can account for 50%
of the total cost2
Drilling Process
A Drill pipe
B Drill string
AE g
C Drill bit
D Rock cuttingsFB
E Annulus
F Solid ti
Dseparationdevices
C
3Source: Schlumberger Excellence in Educational Development (SEED)
Drilling Cycle
Drill pipe
i h h
Turbulent zone
i dj d
ill biProperty
o High shear zoneo High temperature
Properties adjusted with additives
Drill bit Property Adjustment
o Laminar flow
Well annulus
Solids control
o Filter‐cake formation
o Cuttings transport
Shale shakers, centrifuges etc. with
Low shear rate
4
o Cuttings transport
Functions of Drilling Fluids
o Remove and transport drilled cuttings
Removal increases rate of penetration Removal increases rate of penetration
o Cool and lubricate the drill bit
Increase lifespan of the bit
o Seal the wall in permeable formations
Form a filter cake to reduce loss of circulation
o Control pressure in the drilled formationo Control pressure in the drilled formation
Stability and efficiency affected greatly by pressure Manage gas kicks formation liquid invasion etc Manage gas kicks, formation liquid invasion etc.
5
Functions of Drilling Fluids
o Minimize reservoir damage
Permit formation evaluationo Permit formation evaluation
o Maintain well‐bore stability
o Prevent corrosion and excessive wear
o Facilitate cementing and completiono Facilitate cementing and completion
o Inhibit gas hydrate formation
o Neutralize corrosive gases encountered
6
Components of Water-based MudsWaterFreshwater, seawater, brines
Base fluidSolubleThinners
InertOther minerals
Water‐based muds
Thinners, salts, …
ReactiveSmectite
mudsMud system High density
Weighing material,Solids
Drilled cuttings
Low density
Weighing material, insoluble salts
7
Low densityClays, polymers
Components of Non-aqueous Muds
External phase
Base fluidEsters, diesel, mineral oilssynthetic fluids like olefins,
phase
Soluble additives
Non‐aqueous Muds
Soluble additivesSurfactants, rheology modifiers, thinners, Internal phase
Lime, glycols, acetates, Muds
Mud systemOrganophillic clays, weight
nitrates
Solids
material, CaCO3
Drilled
8
Drilled cuttings
HP/HT Drilling Challenges
o Meet the demanding conditions
Depths > 20000 ft Pressures up to 2000 bar Depths > 20000 ft , Pressures up to 2000 bar, Temperatures up to 250°C
o At extreme conditions low ROP leads to higho At extreme conditions low ROP leads to high costs
ddi i d d Additive degrade Mud breaks down Mud behavior difficult to predict
o Performance vs. Environmental acceptance
9
Design Process
o Identify possible
FormulateoDevelop
oAssess current muds
oDefine needs
o Identify possible additives
oFormulate d l
oDevelop algorithms to span the search spaceoDefine needs
Assesproperty models space
Design
10
Assessment of Current Muds
o Asses conditions of failure for current drilling fluids and additivesfluids and additives
Define the targets for Computer‐Aided Molecular Design (CAMD)Design (CAMD)
o Identify classes of components used for drilling
lo Over 500 patents in just last 10 years
o Review of drilling fluid additives tailored for gextreme conditions
11
Future Directions
o CAMD is an effective technique used for product
designdesign
o Key directionsy
Polymer additive design
h i b fl id d i Synthetic base fluid design
Surfactant system design
Tailoring mixture properties for optimal drilling
parameters
12
p
Temperature Effects
o Examine the current additives
Stability and applicability range Stability and applicability range
o Degradation needs to be considered
Rate of decomposition as function of temperature
o Model for stability of mixtures
Colloidal mixture property models Effects of temperature on colloidal stabilityp y
o Develop and include stability models
13
Polymer Additives
Approaches to polymer design
Group Contribution (GC)o Group Contribution (GC)
Contributions for some polymer properties using monomer structure
o Quantity‐Structure Property Relations (QSPR)
Diverse structural descriptors to predict properties
o Connectivity Indices (CI)y ( )
Topological indices as descriptors for backbone and pedant groupsp g p
14
Polymer Design Challenges
o GC, CI fail with increasing size and complexity
Difficult to include effects ofo Difficult to include effects of
Branching Co‐polymers
o Lack of quality data for different systems
o Uncertainty present in property prediction
Polymer additives deteriorate at higho Polymer additives deteriorate at high temperature
15
Other Key Areas
o Base fluid design
Targets: Expected rheology and stability Targets: Expected rheology and stability Environmentally conscious design
C ll id l i t d io Colloidal mixture design
Composition selection based on mixture stability lmodels
Optimal weighing material size distribution
o Surfactant systems
o Lost‐circulation material
16
