Candidate Selection - Overview
-
Upload
kevin-steinbach -
Category
Documents
-
view
16 -
download
7
description
Transcript of Candidate Selection - Overview
Candidate Selection - Overview
• The objective of candidate selection is to find the optimum stimulation candidates using accepted tools.
• Candidate progression involves grading those initial selections through a wellwork hopper to gain maximum impact.
• Application excellence makes the difference between success and failures on even the best wellwork candidates.
8/25/2015 1 George E. King Engineering
GEKEngineering.com
Reasons for failures
• Many re-completion and re-stimulation jobs fail because the work was focused only on underperforming wells.
• Production data alone is not a basis for re-stimulation or other wellwork considerations.
8/25/2015 2 George E. King Engineering
GEKEngineering.com
Know the Flowing System
Source – Chirag PTL 8/25/2015 3 George E. King Engineering
GEKEngineering.com
The effect of damaged permeability layers in the
formation flow path. [ks* ke * (re/rw)] kavg = [ks * ln (re/rs)] + [ke * (ln re/rs)] kavg = avg perm thru the reservoir plus damaged layer ks = permeability thru the damaged layer ke = perm in the undamaged reservoir re = reservoir drainage radius of the well rs = radius of damaged (or stimulated zone) rw = radius of the wellbore
8/25/2015 4 George E. King Engineering
GEKEngineering.com
Sources of the Best Wellwork • Reservoir
– Understand Channels
– Pressure Support
– Water and Gas control
– Infield drill
– Stimulate
– Inflow restrictions
– Waterblock
– Condensate Banking
– Bypassed pay
• Downhole – Lift
– Deliquification
– Deposits and restrictions
– Perf and Reperf
– Integrity Repair
– Friction limited
• Surface
– De-bottle
neck
– Choke
setting
– Gathering
line
– Separator
pressure
– Water and
gas
handling
• Injector
– Conforma
nce
control
– Fill
– Control of
x-flow
– Backflow
control
• Operations
– Up-time
– Optimizati
on
frequency
– Bean-up
Strategy
– Flux
Strategy
8/25/2015 5 George E. King Engineering
GEKEngineering.com
What works the best?
• Look at the whole flowing system • Know your wellstock • What wellwork has been done? – what has worked,
what hasn’t, and why? • Identify the controlling limits or choke points. • Start with the best wells, but assess the poor wells
for anomalies • Look at all the opportunities and the options • Risk assess, rank opportunities and group work. • Timing, people availability, rig availability, access are
all important controls.
8/25/2015 6 George E. King Engineering
GEKEngineering.com
Some Effective Parameters for Candidate Selection
Parameters used in
candidate selection
Importance How can it be
improved?
Recoverable
Hydrocarbon Reserves
What is remaining and
movable?
What can make it more
mobile?
Reservoir Pressure Pressure is the driving
energy
Floods, gas inj.,
Fh – porosity-feet A simple comparative
measurement of pay
quality
Well placement and
Reservoir contact :
laterals, fracs, etc.
Conformance Review Minimizes fluid
handling
Determine what fluids
are flowing & where
Lift optimization Ensures that the
maximum drawdown
can be placed on pay.
Survey the lift system
and check key
indicators.
8/25/2015 7 George E. King Engineering
GEKEngineering.com
Common Traits of Successful Re-stimulation Re-Completion Projects.
1. Complex reservoirs (shales, coals, bedded, tilting, compartmentalized, discontinuous, etc.)
2. Low reservoir drive energy where water-flood or gas injection is possible.
3. Poor initial fracture design. Short fractures in tight gas reservoirs or low conductivity fractures in higher rate potential wells.
4. Opportunity for application of specialized technological advances, i.e., fit for purpose in a field.
5. Older wells that have been damaged by production of repair operations.
6. Wells with limited entry or limited wellbore-to-reservoir contact.
8/25/2015 8 George E. King Engineering
GEKEngineering.com
Common Traits of Successful Re-stimulation / Re-Completion Projects.
7. Extremely thick zones of variable horizontal permeability and very low vertical formation permeability.
8. Infield Drilling Opportunities where fluid viscosity favors drilling (vertical or horizontal) over fracturing.
9. Cased, cemented and perforated completions in very high rate formations.
10. Wells with conformance control issues where water or gas can be controlled without reducing hydrocarbon flow.
11. Flow restrictions (chokes, small flow lines, excessive bends)
12. Well Repair – bringing on shut-in wells (integrity problems).
13. Reserve progression – Non-Proved to Proved-Developed.
8/25/2015 9 George E. King Engineering
GEKEngineering.com
Complex Reservoirs
• Completions in complex reservoirs are usually the result of trial and error completions.
• Near-field and Far-field stresses may alter the direction of a frac once it leaves the near wellbore area.
• Polymers can damage coals and some shales. Inability to break polymers leaves the formation and the fracture pack damaged and low conductivity.
• The length of the fracture can be critical in effectively accelerating the production of
8/25/2015 10 George E. King Engineering
GEKEngineering.com
Frac Length Variation with Permeability
The fracture length ranges are averages of what has typically been use,
8/25/2015 11 George E. King Engineering
GEKEngineering.com
Frac Length Effect on Skin
-5.0
-4.5
-4.0
-3.5
-3.0
-2.5
-2.0
-1.5
-1.0
-0.5
0.0
0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0
FCD
Fra
ctu
re S
kin
Frac Length = 50 ft
Frac Length = 100'
rw = 10"
The FCD, or dimensionless fracture capacity, is a comparison of frac conductivity to that of the formation. Low skins are possible where the fracture is significantly more conductive than the formation – yet even in high formation permeabilities, fracturing benefits the production simply by breaking through the near wellbore damage.
8/25/2015 12 George E. King Engineering
GEKEngineering.com
Rock Variability – what effect on flow?
• Permeability data from Permian dolomitized shallow-water platform carbonate outcrops in west Texas and New Mexico exhibit two to five orders of magnitude variability, most of which occurs within distances of a few feet [1 m] within single rock-fabric units. (SPE-65370 – Jennings)
• Fluid-flow simulations demonstrate that some long-range features control overall flow behavior even when short-range variability composes most of the variance. The short-range heterogeneities produce local smearing of displacement fronts.
8/25/2015 13 George E. King Engineering
GEKEngineering.com
What is the source of the
well under-performance
problem? • Ineffective or problematic initial completion
– Problems from design, execution or damage, poor perfs, poor connection with reservoir (not matched to flow paths).
• Pressure depletion – Frac geometry change, loss of drive pressure, out-
gassing, loss of light ends, increasing deposits, water influx
• Damage during production operations – Deposits resulting from shear, temperature change,
out-gassing or mixing incompatible fluids (paraffin, asphaltenes, scale, salt, etc.)
– Phase changes from dew point, bubble point, water 8/25/2015 14
George E. King Engineering GEKEngineering.com