Introduction to Underbalanced Drilling Technology

1
Introduction to Underbalanced Drilling Technology
Lesson 2
Harold Vance Department of Petroleum Engineering
2
Wellsite UBD Equipment
Harold Vance Department of Petroleum Engineering
3
UB Drilling - Jobs
Harold Vance Department of Petroleum Engineering
4
Underbalanced Drilling in the United States
YEAR
Harold Vance Department of Petroleum Engineering
5
Underbalanced DrillingWells by Region
Harold Vance Department of Petroleum Engineering
6
Formation Pressure is Equal to or Greater than
Circulating Pressure.
UBD Definition

Harold Vance Department of Petroleum Engineering
7
UBD - Types

• Normally Pressured Reservoirs.
• Applications for normal to above normal pressured
  reservoirs utilizing fluid systems in a
  controlled flow (mudcap) drilling technique.
• Depleted Reservoirs.
• Where a multi-phase circulating fluid is
  necessary to achieve required Bottom Hole
  Circulating Pressure (BHCP)- underbalanced or
  with minimal overbalance.

Harold Vance Department of Petroleum Engineering
8
Barriers to UB Drilling
Harold Vance Department of Petroleum Engineering
9
Regulatory Barriers to Underbalance Drilling

• The regulators need assurance and details.

Harold Vance Department of Petroleum Engineering
10
Barriers To UB DC

• Regulatory
• Lack of standards.
• Lack of knowledge.
• Little statistical history.
• Concern about well control.
• Environmental questions.

Harold Vance Department of Petroleum Engineering
11
Operators Barriers

• The operator needs experience and confidence.

Harold Vance Department of Petroleum Engineering
12
Operators Problems

• Unfamiliar with the system
• Risk of the new.
• Lack of experienced people.
• Economics - Too expensive.
• Concern- liability.
• Concern- well bore stability.

Harold Vance Department of Petroleum Engineering
13
Reasons For UB Growth

• There are driving
• economic reasons.

Harold Vance Department of Petroleum Engineering
14
UBD Forecast by Region
Harold Vance Department of Petroleum Engineering
15
Reasons For UB Growth

• Depleted reservoirs.
• Awareness of skin damage.
• Limits of lost circulation material.
• Cost of differential sticking.

Harold Vance Department of Petroleum Engineering
16
Reasons For UB Growth

• Service company competition.
• Trade journal publications.
• Horizontal drilling.
• Consultants available.

Harold Vance Department of Petroleum Engineering
17
Technical Improvements

• We were not ready to put all of this together
  until the 1990s.

Harold Vance Department of Petroleum Engineering
18
Technical Improvements

• Compressor evolution.
• Hammer drills.
• Nitrogen.
• Increased availability.
• Reduced cost.
• On site generation.

Harold Vance Department of Petroleum Engineering
19
Technical Improvements

• Recyclable foam systems.
• Better gas separators.
• Closed loop circulation.
• Hydraulics models.
• Improved rotating heads.
• Wire line wet connect.

Harold Vance Department of Petroleum Engineering
20
Technical Improvements

• Improved MWD.
• Rig assist snubbing units.
• Coiled tubing equipment.
• Non-damaging drilling fluids.
• Top drive.

Harold Vance Department of Petroleum Engineering
21
Working On

• Well control concepts.
• Deployment valves.
• Casing drilling.
• Expandable casing.
• Expandable sand screens.
• Retractable bit.

Harold Vance Department of Petroleum Engineering
22
Completion Techniques

• Improved gravel packing fluids.
• Improved completion fluids.
• General technique improvement.

Harold Vance Department of Petroleum Engineering
23
Reasons For UB Drilling

• Lost circulation.

Harold Vance Department of Petroleum Engineering
24
Reasons For UB Drilling

• Lost circulation.
• Faster drilling.

Harold Vance Department of Petroleum Engineering
25
Reasons For UB Drilling

• Lost circulation.
• Faster drilling.
• No differential sticking.

Harold Vance Department of Petroleum Engineering
26
Reasons For UB Drilling

• ...
• Reduce reservoir damage

Harold Vance Department of Petroleum Engineering
27
Reasons For UB Drilling

• ...
• Reduce reservoir damage.

• Improve production evaluation.

Harold Vance Department of Petroleum Engineering
28
Effect Of Skin On Production Rates
BOPD
1,000
800
600
400
200
0
5
10
-2
0
15
-3
-1
SKIN
Harold Vance Department of Petroleum Engineering
29
Physical Limits to UB Drilling

• Borehole instability
• Poor casing point

Harold Vance Department of Petroleum Engineering
30
Physical Limitation to UBD

• Borehole Instability.
• Unconsolidated sands.
• Weak formations.
• Geopressured shales.
• Salt beds.
• Inadequate Casing.

UBD is another tool in the toolbox, not a Panacea.
Harold Vance Department of Petroleum Engineering
31
Production Limits to UBD

• Permeability is so low the zone needs to be
  fractured.
• Zones must be isolated.

Harold Vance Department of Petroleum Engineering
32
Types of Flow Regimes
MIST
GAS
AERATED
FOAM
LIQUID
LIQUID
Harold Vance Department of Petroleum Engineering
33
Fluid Phase Continuity
Harold Vance Department of Petroleum Engineering
34
GeneralizedFluid Systems
Harold Vance Department of Petroleum Engineering
35
Equipment - Rotating Head

• Shaffer rotating blow-out preventor.
• 2,500 psi rotating - 5,000 psi static.

Harold Vance Department of Petroleum Engineering
36
Closed Loop Circulation System
FLARESTACK
SEPARATOR
SAMPLE
CATCHERS
TOP
OIL
DRIVE
TANKS
SYSTEM
NITROGEN
CHOKE
PUMPERS
MANIFOLD
R-BOP
WATER
TANKS
RETURN
RIG
CUTTING
MUD
RIG PUMPS
TANKS
N 2 / FLUID MIX
Harold Vance Department of Petroleum Engineering
37
Choke Manifold
Harold Vance Department of Petroleum Engineering
38
Equipment - Separators
Harold Vance Department of Petroleum Engineering
39
Equipment - Gas Source
Carbon Steel
Vaporizer
Liquid Nitrogen (-320OF)
Pump
Gaseous N2 to well 80OF, 0-10,000 psi
Stainless Steel
Harold Vance Department of Petroleum Engineering
40
Equipment - Lots More
To shale shaker
ESD
Manifold
Sample catchers
Willis choke
Flare
Separator 200 psi vessel
Rig Manifold
Choke
Oil storage/transport Water returned to tanks
HCR
Flare pit
Choke
Harold Vance Department of Petroleum Engineering
41
AIR DRILLINGA Brief Summary
Harold Vance Department of Petroleum Engineering
42
Air Drilling

• Air/Gas drilling (dust) is a technique used in
  areas where the formations are Dry i.e., there
  is no influx of water or liquid hydrocarbons.
• This medium requires significant compressed gas
  volumes to clean the well with average velocities
  of over 3,000 ft. per minute.

Harold Vance Department of Petroleum Engineering
43
Air Drilling Dusting
Harold Vance Department of Petroleum Engineering
44
Air Drilling Benefits

• Increased Rate of Penetration.
• Reduced Formation Damage.
• Improves Bit Performance.
• Lost Circulation Control.
• Continuous Drill Stem Test.

Harold Vance Department of Petroleum Engineering
45
Air/Dust Drilling Layout
Harold Vance Department of Petroleum Engineering
46
Air Drilling Waited Upon Large Portable
Compression
Simple and convenient to drill with air
inexpensively and anywhere.
Harold Vance Department of Petroleum Engineering
47
Misting

• Addition of 6 to 30 bbl/hr of fluid to the air
  stream.
• Clean and lubricates the bit.
• Carries the cuttings to the surface as a mist or
  more normally in a modified two phase flow.

Harold Vance Department of Petroleum Engineering
48
FOAM DRILLING
Harold Vance Department of Petroleum Engineering
49
Foam Drilling Basic Comments

• The most versatile of the gas-generated systems.
• Effective operating range from 0.2 to 0.6 s.g.
• Mixture of gas phase and foaming solution.
• Foam flow varies with depth in the hole.
• Adjustable effective BHP.
• Enhanced lifting and well bore cleaning.
• A displacing medium, not a propelling medium.

Harold Vance Department of Petroleum Engineering
50
Foam (Heading)
Harold Vance Department of Petroleum Engineering
51
Improved Hole Cleaning
Harold Vance Department of Petroleum Engineering
52
Foam Drilling Benefits

• Faster penetration rate.
• Low air requirements.
• Low fluid requirements.
• Low hydrostatic head.
• No damage to formation.
• Continuous Drill Stem Test.
• Best for large holes.

Harold Vance Department of Petroleum Engineering
53
Mist or Foam Drilling Layout
Harold Vance Department of Petroleum Engineering
54
Foam Drilling
Harold Vance Department of Petroleum Engineering
55
Gaseated or Aerated Drilling
Harold Vance Department of Petroleum Engineering
56
Aerated Fluid

• Gasification of primary drilling fluid.
• Initially designed as a technique to
• lighten mud to reduce lost circulation.
• Methods.
• Standpipe injection.
• Jet Sub.
• Parasite String.
• Dual Casing String.
• As an UB fluid, it is easiest to control in small
  holes.

Harold Vance Department of Petroleum Engineering
57
Parasite String

• Small injection string run
• simultaneously with intermediate
• casing.

• Injected gas does not affect
• bit hydraulics.
• Injected gas does not effect
• MWD.

Harold Vance Department of Petroleum Engineering
58
Jet Sub

• Similar to parasite string.
• Gas induced thru drill pipe.
• Selective jet sizing dictates amount of air to be
  injected.
• Jets are Similar to Bit Jets.

Harold Vance Department of Petroleum Engineering
59
Parallel Casing String (Teichrob)
N /air
2
N /water
2
N /air/water/oil
2
150 m TVD, 150 m MD
89-mm (3-1/2 in.) Drill Pipe
244.5-mm (9-5/8 in.) Intermidiate Casing
o
177.8-mm (7 in.) Tie Back Liner
724 m MD at 64 inclination
o
159-mm (6-1/4 in.) Hole Diameter
892 m MD at 90 Inclination 694 m TVD
12 m Slotted Joint
o
Foam Cement
o
o
TD 1,440 m MD at 90 Inclination, 696 m TVD
Harold Vance Department of Petroleum Engineering
60
Aerated Fluid Layout
Harold Vance Department of Petroleum Engineering
61
Aerated Drilling Problems
Rotating BOPs
Compressor/N2 Cost
Solid/Liquid/Gas Separation
Corrosion
Hydraulic Calculations
Vibration
Cuttings Lifting
Fluid Influx
Fire/ Explosions
Underbalanced Completion
High Torque/ Drag
Borehole Stability
MWD Transmission
Harold Vance Department of Petroleum Engineering
62
UB Drilling Completions Manual

• Candidate selection.
• Air/gas/N2/mist drilling.
• Foam drilling.
• Aerated fluid drilling.
• Flow live drilling.

Harold Vance Department of Petroleum Engineering
63
UB Drilling Completions Manual

• Surface equipment.
• Downhole equipment.
• Field operations.
• Downhole problems.
• Environment, safety,
• regulations.

Harold Vance Department of Petroleum Engineering
64
End of Lesson 2
Harold Vance Department of Petroleum Engineering