A Mapping of gulf coast strike slip faults To the left is a set of associated strike slip and adjustment faults on the.
Download ReportTranscript A Mapping of gulf coast strike slip faults To the left is a set of associated strike slip and adjustment faults on the.
Slide 1
A
Mapping of gulf coast strike slip faults
To the left is a set of associated strike slip and adjustment faults on
the Lousiana coast. The section itself may be thought of as a series
of simulated sonic logs. It is land data, of medium quality. The work
is an extension of my strike-slip North Sea work.
Important preliminaries –
Before starting on supporting details consider this slide.
I jumped to a spot in the project where faults were so clear they
stand by themselves. Within any one fault block there is almost no
stratigraphic thinning or thickening, while between blocks substantial
changes occur. On fault A you will see this overall difference result in an
apparent normal attitude at the top and a reverse fault attitude at the
bottom Also note that the “drag effects” often disagree with the fault
slope. These factors, plus the curved nature of the faults themselves tell
us we are looking at strong parallel movement. Some adjustments are
inevitable but strike slip is the nature of the main structure.
Within the main series we see probable salt intrusions affecting the
structure. This phenomenon makes it tough to track the faults at depth.
The first structural priority of this study is to understand the highly faulted
intermediate section.
The motivations for this show are several. As an unreconstructed
structural geologist, the ability to see this complex geology is exciting,
even if no others pay attention. The probability that missed reservoirs
can be found within the bounds of this shooting raises my personal
economic frustration level. Finally, the fact that the ADAPS resolution
system is not yet accepted keeps me awake at night.
On the slide pair that follows I ask you to spend time toggling back
and forth between the stacked input and my detuned output. I hope you
pay close attention to the lithologic character being brought out. Nowhere
is correlation quality more important than in complexly faulted zones. To
understand the importance of horizontal movement is basic to structural
geology. In short there are many facets to study.
?
On the next slide I show that mapping these faults has an economic
justification by pointing to previous drilling activity..
To prepare this short show I ran 74 in-lines, then repeated with
no detuning. My first concern was whether I could satisfactorily track the
faults from one end of the prospect to the other. Satisfied that I could, I
then just interpreted a short series to prove my point. This set follows.
Toggling – If you have never used this method of comparing, please
spend some extra time on the next two slides. Use the arrow keys.
Slide 2
Please toggle w arrows –
(use the “right” one here.)
Straight stack (the input)
Slide 3
Please toggle w arrows
Please notice
the greatly improved clarity
of the fault breaks. While they are visible on the
input (toggle with left arrow to see), it would
have been hard to establish the pattern without
this improvement.
As important (but more subtle) is
the increased geologic believability supplied by
the sonic log nature of the final product. While
toggling you will hopefully notice that a number
of superfluous lobes have been eliminated from
the input (left slide) by the advanced detuning.
Later you’ll see a set of in-lines
with the faults defined. It is important that you
notice how consistent the patterns are, even
though every fifth one was chosen. There are
Detailed changes, but they follow a believable
transition. This consistency is a logical proof of
the system itself.
Before going to that series,
I will
show you that a bunch of wells were drilled in
this faulted zone. I have no knowledge of their
targets, but since they are older, one would
assume they found oil in the zone we are
looking at.
So, if you are through toggling,
click anywhere to see the drilling perspective
mentioned.
ADAPS high resolution output.
Slide 4
My statements on previous drilling
come from the partial
map shown below. The section at the left traverses along the red line on
this excerpt. These early wells predate the seismic shooting.
While I have not extended my fault series this far,
let me say the pattern we see here is very similar to what you have seen
on the first slide, and will see on the following group . Orienting yourself
between the mapped line and the section, you should agree that most of
the wells fall within the obviously faulted zone.
The challenge for ADAPS is to show where they found the
oil.Unfortunately, the owner of this data objected to my showing a portion
of the project map that showed many old wells drilled in the faulted area.
They appeared to have no interest in that zone, being mainly concerned
with deep events that are not clearly defined even in this advanced work.
Comments blanked
for security.
In any case you will just have to take my word that those wells
exist.
Before intelligent detuning,
section amplitudes derive from
individual primary reflections. These, in turn, come from both the tops
and the bottoms of lithologic beds. Depending on detailed interface
amplitudes for hydrocarbon indicators is fairly dangerous. Sonic log
simulation attempts to measure the energy coming from the integrated
beds. While not always perfect, this transition seems to check out nicely
Many ADAPS great well matches
verify this observation.
A collection of examples can be accessed via the ADAPS router..
Most oil & gas will be long gone from this old field,
but we should be able to spot obvious trapping situations, and we may
find missed reservoirs. Early in the ADAPS development game I was
encouraged to see abrupt positive amplitude changes connected with
obvious trapping situations. Hopefully you will find some of these in the
next series.
After the fault displays
displaying a few promising in-lines.
I go through the entire prospect,
Slide 5
Series start –
I suggest you tab through
quickly to see how the fault
pattern holds for the eight
in-lines. At the end you will
be given a repeat option.
Next time through take
the time to see the geologic
reasonableness I spoke of,.
Sine this is a form of logical
proof.
Notice the cases where
the event correlation is
good across a fault, yet
there is a big change in
amplitude. Could it be the
bright spots were missed?
Keep running through
the series, noticing how the
bright spots carry from one
in-line to the next. This is
direct reservoir detection!
?
?
?
Slide 6
#2
Note the remaining
bright spots holding
steady.
?
?
?
Slide 7
#3
Deep plate movement –
While we are here, some talk on
the difficulty presented by lateral
faults is in order. Old habits die
hard, and we’re used to searching
for nicely lined up vertical throws.
In cases where the stratigraphy is
constant, we might see no offsets
across major strike slip faults! It
could well be that once we start
looking intelligently we will find
that this type of structure (caused
by deep plate movement) is very
common.
Slide 8
#4
The more you work with
parallel faults the more
you’re willing to believe
the quirky twists. Shear
is the determining thing.
Here it is horizontal. If
these faults were normal
the twists would have
been sheared off.
Slide 9
#5
Too much salt is bad, and it
certainly has given us problems in
seismic interpretation. While this is
pure conjecture, what might have
started as a major (but simple) set of
lateral faults turned into a complex
structure when weaknesses along
the faults allowed salt to be injected.
Since much current emphasis is on
deeper events, our challenge is to
extend our resolution downward.
Slide 10
A
#6
Fault A is probably major
here. Stratigraphic correlations across
the others are fairly good, with minor
layering changes, while there’s almost
no matching in the upper zone on this
one. Deeper events do better, but this
is probably because the stratigraphy is
more constant down there.
Slide 11
#7
See comments on #5.
Slide 12
#8
End of interpreted series.
Click to repeat.
Or click elsewhere to see a few
hot spot examples outside the
developed area.
Slide 13
Concentrate on geologic believability
within the individual fault blocks. You might note I might
have added a couple more detail faults at the very center,
I wager they’ll show up on adjacent in-lines if I run them.
Once you believe (as I do) in what you are seeing, picking
faults gets easier.
Probable reservoir A is another example where the
amplitude increases across a fault (in an obvious trapping
situation).
A
Slide 14
To end the show – Possible reservoir A is
a good example of what I look for, both in
structure and amplitude.
And note the big stratigraphic differences
across the arrowed fault. Obviously there a large
horizontal movement is involved. This one reality,
coupled with the splintered nature of the reservoirs
obviates the use of most current automatic picking
and mapping routines. The kind of analysis done
here seems an obvious precursor to any drilling.
Click here to start over.
Or here to repeat faults.
A
Or here for ADAPS router.
Or here for well matches.
(Give it time to load.)
A
Mapping of gulf coast strike slip faults
To the left is a set of associated strike slip and adjustment faults on
the Lousiana coast. The section itself may be thought of as a series
of simulated sonic logs. It is land data, of medium quality. The work
is an extension of my strike-slip North Sea work.
Important preliminaries –
Before starting on supporting details consider this slide.
I jumped to a spot in the project where faults were so clear they
stand by themselves. Within any one fault block there is almost no
stratigraphic thinning or thickening, while between blocks substantial
changes occur. On fault A you will see this overall difference result in an
apparent normal attitude at the top and a reverse fault attitude at the
bottom Also note that the “drag effects” often disagree with the fault
slope. These factors, plus the curved nature of the faults themselves tell
us we are looking at strong parallel movement. Some adjustments are
inevitable but strike slip is the nature of the main structure.
Within the main series we see probable salt intrusions affecting the
structure. This phenomenon makes it tough to track the faults at depth.
The first structural priority of this study is to understand the highly faulted
intermediate section.
The motivations for this show are several. As an unreconstructed
structural geologist, the ability to see this complex geology is exciting,
even if no others pay attention. The probability that missed reservoirs
can be found within the bounds of this shooting raises my personal
economic frustration level. Finally, the fact that the ADAPS resolution
system is not yet accepted keeps me awake at night.
On the slide pair that follows I ask you to spend time toggling back
and forth between the stacked input and my detuned output. I hope you
pay close attention to the lithologic character being brought out. Nowhere
is correlation quality more important than in complexly faulted zones. To
understand the importance of horizontal movement is basic to structural
geology. In short there are many facets to study.
?
On the next slide I show that mapping these faults has an economic
justification by pointing to previous drilling activity..
To prepare this short show I ran 74 in-lines, then repeated with
no detuning. My first concern was whether I could satisfactorily track the
faults from one end of the prospect to the other. Satisfied that I could, I
then just interpreted a short series to prove my point. This set follows.
Toggling – If you have never used this method of comparing, please
spend some extra time on the next two slides. Use the arrow keys.
Slide 2
Please toggle w arrows –
(use the “right” one here.)
Straight stack (the input)
Slide 3
Please toggle w arrows
Please notice
the greatly improved clarity
of the fault breaks. While they are visible on the
input (toggle with left arrow to see), it would
have been hard to establish the pattern without
this improvement.
As important (but more subtle) is
the increased geologic believability supplied by
the sonic log nature of the final product. While
toggling you will hopefully notice that a number
of superfluous lobes have been eliminated from
the input (left slide) by the advanced detuning.
Later you’ll see a set of in-lines
with the faults defined. It is important that you
notice how consistent the patterns are, even
though every fifth one was chosen. There are
Detailed changes, but they follow a believable
transition. This consistency is a logical proof of
the system itself.
Before going to that series,
I will
show you that a bunch of wells were drilled in
this faulted zone. I have no knowledge of their
targets, but since they are older, one would
assume they found oil in the zone we are
looking at.
So, if you are through toggling,
click anywhere to see the drilling perspective
mentioned.
ADAPS high resolution output.
Slide 4
My statements on previous drilling
come from the partial
map shown below. The section at the left traverses along the red line on
this excerpt. These early wells predate the seismic shooting.
While I have not extended my fault series this far,
let me say the pattern we see here is very similar to what you have seen
on the first slide, and will see on the following group . Orienting yourself
between the mapped line and the section, you should agree that most of
the wells fall within the obviously faulted zone.
The challenge for ADAPS is to show where they found the
oil.Unfortunately, the owner of this data objected to my showing a portion
of the project map that showed many old wells drilled in the faulted area.
They appeared to have no interest in that zone, being mainly concerned
with deep events that are not clearly defined even in this advanced work.
Comments blanked
for security.
In any case you will just have to take my word that those wells
exist.
Before intelligent detuning,
section amplitudes derive from
individual primary reflections. These, in turn, come from both the tops
and the bottoms of lithologic beds. Depending on detailed interface
amplitudes for hydrocarbon indicators is fairly dangerous. Sonic log
simulation attempts to measure the energy coming from the integrated
beds. While not always perfect, this transition seems to check out nicely
Many ADAPS great well matches
verify this observation.
A collection of examples can be accessed via the ADAPS router..
Most oil & gas will be long gone from this old field,
but we should be able to spot obvious trapping situations, and we may
find missed reservoirs. Early in the ADAPS development game I was
encouraged to see abrupt positive amplitude changes connected with
obvious trapping situations. Hopefully you will find some of these in the
next series.
After the fault displays
displaying a few promising in-lines.
I go through the entire prospect,
Slide 5
Series start –
I suggest you tab through
quickly to see how the fault
pattern holds for the eight
in-lines. At the end you will
be given a repeat option.
Next time through take
the time to see the geologic
reasonableness I spoke of,.
Sine this is a form of logical
proof.
Notice the cases where
the event correlation is
good across a fault, yet
there is a big change in
amplitude. Could it be the
bright spots were missed?
Keep running through
the series, noticing how the
bright spots carry from one
in-line to the next. This is
direct reservoir detection!
?
?
?
Slide 6
#2
Note the remaining
bright spots holding
steady.
?
?
?
Slide 7
#3
Deep plate movement –
While we are here, some talk on
the difficulty presented by lateral
faults is in order. Old habits die
hard, and we’re used to searching
for nicely lined up vertical throws.
In cases where the stratigraphy is
constant, we might see no offsets
across major strike slip faults! It
could well be that once we start
looking intelligently we will find
that this type of structure (caused
by deep plate movement) is very
common.
Slide 8
#4
The more you work with
parallel faults the more
you’re willing to believe
the quirky twists. Shear
is the determining thing.
Here it is horizontal. If
these faults were normal
the twists would have
been sheared off.
Slide 9
#5
Too much salt is bad, and it
certainly has given us problems in
seismic interpretation. While this is
pure conjecture, what might have
started as a major (but simple) set of
lateral faults turned into a complex
structure when weaknesses along
the faults allowed salt to be injected.
Since much current emphasis is on
deeper events, our challenge is to
extend our resolution downward.
Slide 10
A
#6
Fault A is probably major
here. Stratigraphic correlations across
the others are fairly good, with minor
layering changes, while there’s almost
no matching in the upper zone on this
one. Deeper events do better, but this
is probably because the stratigraphy is
more constant down there.
Slide 11
#7
See comments on #5.
Slide 12
#8
End of interpreted series.
Click to repeat.
Or click elsewhere to see a few
hot spot examples outside the
developed area.
Slide 13
Concentrate on geologic believability
within the individual fault blocks. You might note I might
have added a couple more detail faults at the very center,
I wager they’ll show up on adjacent in-lines if I run them.
Once you believe (as I do) in what you are seeing, picking
faults gets easier.
Probable reservoir A is another example where the
amplitude increases across a fault (in an obvious trapping
situation).
A
Slide 14
To end the show – Possible reservoir A is
a good example of what I look for, both in
structure and amplitude.
And note the big stratigraphic differences
across the arrowed fault. Obviously there a large
horizontal movement is involved. This one reality,
coupled with the splintered nature of the reservoirs
obviates the use of most current automatic picking
and mapping routines. The kind of analysis done
here seems an obvious precursor to any drilling.
Click here to start over.
Or here to repeat faults.
A
Or here for ADAPS router.
Or here for well matches.
(Give it time to load.)