Seismic Sequence Stratigraphy - Science topic

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Thanks dear Mario, Jorge and Irving for These helpful answers

Alejandro:

Have a look at this link for broad stratigraphic range (could be updated):

Best

Syed

I think that a good answer would be: it depends! In large scale exploration, it may be enough if you keep the sequence stratigraphical analysis in the lower frequency packages. But if you are working in a field development, you may need to go to higher frequencies to understand the facies distribution. In many cases, you may also find difficult to define the "end" of the stratigraphic approach (end of external controls as sea level or tectonics). In this case, you will be entering in the world of architectural element (facies associations) and sub-environment of deposition (architectural element association), "packages" that not necessarily have external control. I have a good summary of this question in the attached paper.

Dear Dr. Widdowson,

I am very sorry, however I am not an expert in this field of Research.

Cheers

K.H.

Diego,

in this example, a simple dip-filter would do. You can even use a common graphic filter found in Photoshop, for example. Try different graphic filters, like emboss, etc. Please also read papers by Roald Heggland and Paul Meldahl, who used Neural Networks to produce numerical attributes that would enhance such structures (Chimney Cube), see here: https://www.researchgate.net/profile/Roar_Heggland/publication/262672920_The_chimney_cube_an_example_of_semi-automated_detection_of_seismic_objects_by_directive_attributes_and_neural_networks_Part_I_methodology/links/54ad09380cf24aca1c6bb081.pdf

Hello Helna,

Thanks for reply.

Here the purpose is Seismic hazard analysis.The mine has been closed about 15 years back.I can do monitoring only through surface installation.The area is about 6Km by 3Km and maximum depth of excavation is 3.0 Km.How many geophone should I install for monitoring such area?Should I go for about 14/15 Hz geophone or 4 Hz geophone or a combination of both 4 Hz and 14/15 Hz geophone?

Regards

Vikalp Kumar

In order to define a depositional environment from logs, you need to do correlations between the wells (connect certain rock bodies in one well to those exist in another well) in addition to looking at well signature. A well is only one point and you need to link the points together to understand the depositional environment. You can do that by drawing a line from south to north, east to west, ..etc in all directions and link the bodies to one another. Once that is done, start looking at possible environments and possible depositional direction. At the well level, high NTG and thick sand bodies can tell something different from layered/shaly low NTG. I am attaching a picture for GR signature for a certain environment (Serra and et al., 1975.) and a picture for log signature for certain depositional environment (wikipedia). As you can see from the picture and from the fact (as you know) that lower GR represents larger sand bodies, the self, delta, distributary channels (mouth bar) and aeolian have higher NTG in general than submarine fan.

Other things you can try to do:

1. From logs: check for sequences like  Bouma sequence which tells you that you are dealing with turbidite environment. 

2. From cuttings: check for fossils (living organisms ramaning) and try to define the environment in which such organisms live in. For example, bioturbation indicates shallow marine environment. 

3. Benchmark to nearby fields. Other fields might have the same deposition source for your reservoir. 

4. Use your seismic data to define geometries of the sand bodies (this can help you to limit the possible options or at least eliminate some possibilities). For example, you can recognize channels, submarine fan .. etc easily using seismic data.

There are 4 sources that did the same thing you are trying to do, please search for those:

1. Depositional Environment and Petrophysical

Characteristics of “LEPA” Reservoir, Amma Field,

Eastern Niger Delta, Nigeria

2. Characterization of fluvial hydrocarbon

reservoirs and aquifers: problems and solutions

3. Submarine fans and related depositional systems II] variability in

reservoir architecture and wireline log character

4. Interpretation and recognition of depositional systems using seismic data.

Hi Syed,

I suggest you take a look on the paper " Orbital-driven cyclicity and the role of halokinesis on accommodation within siliciclastic to carbonate, shallow-water Albian deposits in the Espírito Santo Basin, southeastern Brazil".Cretaceous Research. Volume 35, June 2012, Pages 22–32;  DOI: 10.1016/j.cretres.2011.11.008

Besides, you can search for my PhD thesis, which main goal is to define the origin of the carbonate, hybrid and siliciclastic Albian rocks that occur in the Espirito Santo basin, Brazil. Forteen lithofacies were described and organized into eigth facies sucession, whose superposition confirmed an allocyclic nature of the facies succecssion. A depositional/paleoclimate model was proposed to explain the vertical succession of the lithologies within an high-frequency "ideal sedimentary cycle" as well as the regional arrangement of the main lithologies at the 3rd  order scale. On its elaboration, both autogenic (terrigenous input delivered to the coast by ephemeral fluvial floods and in situ production of carbonate - oncolites, bioclastics and oolites - particles  the redistribution of both by longshore currents and storm events and allogenic (climate changes controlled by orbital cycles) processes were taken into account. The sedimentary succession is organized as high-frequency, 100 Ky  cycles (short eccentricity in the Milankovitch scale) forming repeated transgressive-regressive (T – R) cycles. The preservation of the cycicity within the studied section is ascribed to the high siliciclastic sedimentation rate favoring salt escape and increasing accomodation.

Mohammad, regarding the line you have shown, I am assuming that we are only seeing part of the line. Many reflectors dip to the left. Is there a shelf break or other feature giving us a point of reference to the right?

Regarding sequence boundaries, here are a couple things you might think about:

 there are three high amplitude (negative) horizons. These may be máximum flooding surfaces. That is, when sealevel is at its highest, condensed sequences may be deposited in deep wáter. They tend to be high in radioactivity associated with marine anoxic deposition of fines, give a swing to the right (low) gamma ray on logs, have a low velocity (hence the big negative amplitude) and may be source rocks. This would imply you are looking at a deepwater setting.

Bottom right at over 2000 milliseconds, may be showing some downlap suggesting sediment supply from the right.

Similarly, on the right between 1500 and 1400 msecs, below the middle high-amplitude horizon, there may be successive downlaps towards the left, also suggestng sediment supply from the right.

Between 1400 and 1800 msec at shotpoint 281, a sequence thins on to the anticline. implying the anticline was there before that sequence was deposited. However the anticline was likely reactivated as it is evident up to about 1150 msec.

In general, a good source would be this: http://www.sepmstrata.org/page.aspx?&pageid=229&3

It is from SEPM and there are many pages of instruction regarding sequence stratigraphy and seismic interpretation.

The anticline appears to be faulted but faults may be near vertical.

If you want to provide more background, or information, maybe we could be more helpful. At present, we are blind insofar as we have one part of one line, and no context.

Best wishes,....

Generally, sequence stratigraphic interpretation allows for predictions of the distribution and grain size of sediment across sediment-routing systems and within sedimentary basins. This information is particularly useful for oil and gas exploration and prediction, as the distribution and grain size of sediment is a fundamental control on petroleum systems (especially reservoirs and seals).

Here is a useful reference that introduces the method, terminology, and application of sequence stratigraphy:

Catuneanu, O., Galloway, W. E., Kendall, C. G., Miall, A. D., Posamentier, H. W., Strasser, A., & Tucker, M. E. (2011). Sequence stratigraphy: methodology and nomenclature. Newsletters on Stratigraphy, 44(3), 173-245.

I believe that reference is available for free online.

There are a lot of caveats to sequence stratigraphy, especially regarding the interpretation of drivers/controls. We have written some papers on those limitations in the context of continental margins and deepwater depositional systems. See the following and especially references therein:

Covault, J. A., & Graham, S. A. (2010). Submarine fans at all sea-level stands: Tectono-morphologic and climatic controls on terrigenous sediment delivery to the deep sea. Geology, 38(10), 939-942.

Andrew Miall has written an entire book on stratigraphy that challenges sequence stratigraphic methods and especially the drivers of stratigraphic evolution:

Miall, A. D. (2010). The geology of stratigraphic sequences. Springer.

I hope that these reference help. Apologies if I misunderstood your question.

Best.

Jacob Covault