Energies,
Journal Year:
2024,
Volume and Issue:
17(23), P. 6081 - 6081
Published: Dec. 3, 2024
Deep
coalbed
methane
(CBM)
demonstrates
significant
production
potential,
and
a
fervent
exploration
development
boom
is
currently
underway
in
China.
The
permeability
of
coal
reservoirs
heavily
influenced
by
pore–fracture
structure
heterogeneity.
Some
researches
have
been
conducted
on
deep
coals’
structure;
however,
these
studies
mostly
consider
as
homogeneous
material,
neglecting
the
heterogeneity
macrolithotypes
within
coal.
In
this
study,
33
coals
with
burial
depths
more
than
2000
m
were
obtained
from
Daning-Jixian
block
Ordos
Basin,
covering
all
macrolithotypes:
bright
(BC),
semi-bright
(SBC),
semi-dull
(SDC),
dull
(DC).
These
samples
subjected
to
three
sets
NMR
tests
dry,
fully
saturated,
irreducible
water
conditions,
characteristics
being
analyzed.
results
demonstrate
that
sampled
highly
heterogeneous,
transitional
pores
dominant,
followed
mesopores,
“macropores
fractures”,
micropores.
T2C
ranges
0.61
2.44
ms,
an
average
1.19
ms;
higher
value
indicates
developed
for
producible
porosity
(φpr)
saturation
(Spr)
are
0.31–7.24%
(avg.
2.42%)
6.97–71.47%
31.06%),
respectively.
Both
them
exhibit
high
positive
correlation
total
volumes
fractures”
mesopores.
Compared
SDC
DC,
BC
SBC,
especially
former,
overall
contain
fewer
micropores,
φpr
Spr.
findings
suggest
regions
abundant
SBC
should
be
prioritized
during
CBM
due
inherently
superior
gas
extraction
potential
likely
require
less
intensive
stimulation
achieve
recovery
rates
could
provide
sustainable
over
time.
Earth energy science.,
Journal Year:
2024,
Volume and Issue:
unknown
Published: Sept. 1, 2024
Developing
deep
fragmented
soft
coalbed
methane
(CBM)
can
significantly
enhance
domestic
natural
gas
supplies,
reduce
reliance
on
imported
energy,
and
bolster
national
energy
security.
This
manuscript
provides
a
comprehensive
review
of
commonly
employed
extraction
technologies.
It
then
delves
into
several
critical
issues
in
the
current
stage
CBM
exploration
development
China,
including
compatibility
existing
technologies
with
reservoirs,
characteristics
occurrence
states
desorption
pressure,
generation
mechanisms.
Our
research
indicates
that
China
have
reached
an
internationally
advanced
level,
yet
industry
is
facing
unprecedented
challenges.
Despite
progress
low-permeability,
high-value
coal
seams,
significant
breakthroughs
not
been
achieved
exploring
other
types
seams.
For
different
integrated
developed,
such
as
surface
pre-depressurisation
segmented
hydraulic
fracturing
seam
roof
strata.
Additionally,
techniques
like
large-scale
volume
horizontal
wells
established,
enhancing
reservoir
stimulation
effects
recovery
rates.
However,
all
these
are
fundamentally
based
permeation.
These
lack
direct
methods
aimed
at
diffusion
rate
CBM,
thereby
failing
to
fully
reflect
unique
CBM.
Current
theories
universally
applicable
They
do
adequately
account
for
predominantly
adsorbed
state
complex
variable
mechanisms
further
constrain
China.
Finally,
continuous
new
necessary.
Integrating
more
effective
essential
technical
adaptability
concerning
characteristics,
states,
mechanisms,
ultimately
achieving
efficient
development.
We
conclude
while
possesses
substantial
foundation
fractured
resources,
constrained
requires
utilize
resources
effectively.
Processes,
Journal Year:
2024,
Volume and Issue:
12(7), P. 1318 - 1318
Published: June 25, 2024
The
production
of
deep-coalbed
methane
(CBM)
wells
undergoes
four
stages
sequentially:
drainage
depressurization,
unstable
gas
production,
stable
and
decline.
Upon
entering
the
stage,
recovery
rate
deep
CBM
is
constrained
by
bottom
hole
flowing
pressure
(BHFP).
Reducing
BHFP
can
further
optimize
productivity,
significantly
increasing
wells.
This
paper
optimizes
deliquification
process
for
in
Linxing
Block.
By
analyzing
wells,
an
improved
sucker
rod
pump
proposed,
a
method
considering
flow
tubing,
annulus,
reservoir
established.
Using
data
Well
GK-25D
field
as
example,
optimized
design
was
undertaken,
with
parameters
including
depth
pump,
stroke
length,
rate.
results
show
that
lowers
at
coalbed,
enhancing
well
12.24%.
enriches
technology
CBM,
offering
new
approach
its
development
helping
to
maximize
productivity.
Energy Exploration & Exploitation,
Journal Year:
2024,
Volume and Issue:
unknown
Published: Sept. 10, 2024
This
study
builds
upon
the
research
progress
in
theories
of
CBM
desorption,
diffusion,
and
seepage
flow
to
explore
production
mechanisms
deep
coalbed
methane
(CBM)
Daing-Jixian
block,
aiming
achieve
scientific
reasonable
control
gas
wells.
Theoretical
analysis
suggests
that
adsorption
belongs
liquid–solid
interfacial
adsorption,
encompassing
four
stages:
liquid
phase
adsorption—liquid
desorption—composite
desorption—gas
desorption.
Most
desorbed
is
driven
by
a
pressure
differential
Darcy's
process.
By
calculating
Knudsen
number
(Kn)
under
various
temperature,
pressure,
fracture
diameter
conditions,
state
can
be
identified.
Whole-diameter
CT
scanning
reveals
multi-scale
pore-fracture
system
ranging
from
millimeters
micrometers
nanometers.
Calculations
show
during
well
drainage
depressurization
process,
fractures
millimeter
scale
larger
exhibit
flow,
while
micron-scale
maintain
status
above
reservoir
5
MPa;
other
scales
primarily
non-Darcy
without
significant
macroscopic
movement.
In
summary,
starting
fundamental
original
multiscale
tri-level
pore-permeability
coal
reservoir,
through
post-fracturing
transformation
forming
three
diversion
zones
high,
medium,
low
conductive
regions,
transitioning
free
stages,
an
ideal
comprehensive
model
schematic
for
area
has
been
established,
providing
theoretical
support
on-site
management.
