1_introduction to deepwater systems- definitions_and_concepts

Chapter 1 Introduction to Deepwater Systems: Definitions and Concepts

Overview

This course provides the working geophysicist with a broad overview of the petrole-um systems of deepwater settings. The six main elements of petroleum systems will be cov-ered: reservoirs, traps, seals, source rocks, generation, migration, and timing. The course isdesigned to teach students approximately 80% of what is important. For those interestedin further study of a specific topic, each chapter has extensive references for the current lit-erature. About 10% of the current cutting-edge information remains proprietary and can-not be included.

Deepwater depositional systems are the one type of reservoir system that cannot beeasily reached, observed, and studied in the modern environment, in contrast to other sili-ciclastic and carbonate reservoir systems. The study of deepwater systems requires manyremote-observation systems, each of which can provide only one view of the entire deposi-tional system. As a consequence, the study and understanding of deepwater depositionalsystems as reservoirs have lagged behind those of the other reservoir systems, whose mod-ern processes are more easily observed and documented.

For this reason, geoscientists use an integrated approach, working in interdisciplinaryteams with multiple data types (Figure 1-1). The types of data used in the study of deep-water deposits include detailed outcrop studies, 2D and 3D seismic-reflection data (bothfor shallow and deep resolution), cores, log suites, and biostratigraphy. These data sets areroutinely incorporated into computer reservoir modeling and simulation (Figure 1-1).

The following chapters integrate all of these data types and disciplines to characterizethe many facets of deepwater systems. Technologies for deepwater exploration and devel-opment are improving rapidly. The intent of the course is to provide information that willbe usable even as the technologies advance beyond what we present here.

With that in mind, this chapter introduces basic deepwater terminology and conceptsfor deepwater systems that will be used throughout this book. We will

1) introduce the key definitions of deep water used throughout the course,

2) define the common elements for all deepwater systems,

3) discuss the sequence stratigraphic expression of key intervals and surfaces that boundthe deepwater elements,

4) review the regional controls on the deposition of deepwater systems,

5) discuss scale problems in the comparison between modern and ancient deepwatersystems, and

6) summarize how our understanding of deepwater systems has evolved and discuss theimportant role that technology has played.

Distinguished Instructor Short Course • 1-1

CH01.QXD 7/1/04 11:15 AM -1

Downloaded 10 Dec 2011 to 198.3.68.20. Redistribution subject to SEG license or copyright; Terms of Use: http://segdl.org/

1-2 • Society of Exploration Geophysicists / European Association of Geoscientists & Engineers

Petroleum Systems of Deepwater Settings

Definitions of Deep Water

Geoscientists routinely use several terms to describe the sedimentary processes andcharacteristics of deepwater settings and deposits. For the sake of consistency in this book,we define these terms as follows.

The term deep water is used informally in industry in two ways. First, deep waterrefers to sediments deposited in water depths considered to be “deep,” i.e., those undergravity-flow processes and located somewhere in the upper- to middle-slope region of abasin. Sediment gravity-flow processes are operative in lakes in relatively shallow waterand in cratonic basins where water depths may be less than 300 m. Thus, unless statedotherwise, we use the term deepwater systems to refer to marine-sediment gravity-flowprocesses, environments, and deposits. Other authors have used slightly different terms fordescribing these processes and their deposits, such as turbidite systems (Mutti and Nor-mark, 1987, 1991), turbidite system complex (Stelting et al., 2000), and submarine fans(Bouma et al., 1985).

Second, the engineering definition of deep water refers to modern water depths—specifically, to depths greater than 500 m. That is the depth at which traditional develop-ment rigs cannot be implemented. For this book, when we refer to specific water depths,

Figure 1-1. Diagram showing the different data types used in the study of deepwater systems.Clockwise from upper left: 2D and 3D seismic-reflection data (shallow and deep), wireline logs,biostratigraphy, reservoir modeling and simulation, cores and borehole-image logs, and outcropstudies.

CH01.QXD 7/1/04 11:15 AM Page 1-2



Introduction to Deepwater Systems: Definitions and Concepts

we use the terms as follows. Deep water refers to water depths from 500 to 2000 m, andultradeep water is any water deeper than 2000 m.

Common Deepwater Elements and Terminology

In August 1982, a group of leading deepwater experts met in Pittsburgh, Pennsylva-nia, for what was termed the COMFan I conference (COM = Committee). The meetingproduced the consensus that it was extremely difficult to compare modern submarine fansstudied on the modern ocean floor with ancient ones studied primarily in outcrop (Boumaet al., 1985). As a consequence, there was a need to develop a common language used bydifferent workers in the field. Although many classifications have been proposed for deep-water systems that link disparate data sets, in our experience, three groups of studies wereinfluential in defining terminologies that industry geoscientists now use routinely: (1)Mutti and Normark (1987, 1991); (2) Chapin et al. (1994) and Mahaffie (1994); and (3)Reading and Richards (1994), Richards et al. (1998), and Richards and Bowman (1998).These classifications focused on the kinds of reservoir elements, their architecture andgeometry, and related deposits.

After the COMFan I meeting, Emiliano Mutti and William Normark worked togetherfor several years, attempting to identify the elements common to modern and ancient tur-bidite systems. They produced two seminal papers that were highly influential in geoscien-tists’ understanding and description of turbidite systems (Mutti and Normark, 1987,1991). They identified five elements common to modern and ancient turbidite systems:channels, overbank, lobes (sheets), channel-lobe transition, and erosional features (Appen-dix 1-A). Note that the channel-lobe transition is a zone and erosional features are notdepositional features.

Chapin et al. (1994) and Mahaffie (1994) presented a reservoir classification devel-oped by Shell Oil Company for the key architectural elements the company used in reser-voir characterization during development of their deepwater discoveries in the northernGulf of Mexico. They emphasized three main sand-bearing reservoir elements: sheets (lay-ered and amalgamated), channels (single and multistory), and thin beds comprising levees(Figure 1-2; Appendix 1-A). This classification largely describes the geometry of the ele-ments. As such, workers in industry commonly use it. The classification was based largelyon the classification of turbidite elements introduced by Mutti (1985) and is reviewed ingreater detail in Chapter 3.

Richards et al. (1998) identified five architectural elements common to all turbiditesystems: wedges, channels (including chutes and braided and leveed channels), lobes,sheets, and slides (Figure 1-3; Appendix 1-A). Richards et al. (1998) noted that the occur-rence of these elements is controlled primarily by the sediment grain size and the type ofsediment delivery system (which we review in Chapter 3 of this book).

Elliott (1998) proposed three additional elements common to modern and ancientdeepwater systems: mass-transport complexes, condensed sections, and slides. Appendix1-A includes the terms for elements that will be used throughout this book. The key char-acteristics of each of these deepwater elements will be reviewed in Chapters 4–7. Eachdeepwater element will be summarized in terms of its appearance in seafloor images, andin 2D and 3D seismic data, outcrops, cores, wireline logs, and imaging logs.

CH01.QXD 7/1/04 11:15 AM Page 1-3




Fig

ure

1-2

. R

eser

voir

clas

sific

atio

n fo

r de

epw

ater

res

ervo

irs,

with

em

phas

is o

n th

e no

rthe

rn G

ulf

of M

exic

o. A

fter

Cha

pin

et a

l. (1

994)

.R

epro

duce

d w

ith p

erm

issi

on o

f th

e G

CS

–SE

PM

Fou

ndat

ion.

CH01.QXD 7/1/04 11:15 AM Page 1-4




Sequence Stratigraphic Expression of Key Surfaces and Intervals

It is critical that we understand the key stratigraphic intervals and surfaces thatbound deepwater systems and related elements. These intervals and surfaces have beendefined by integrating observations from modern and ancient turbidite systems, as derivedfrom 2D and 3D seismic data, wireline logs, biostratigraphic data, reservoir pressure data,and outcrops.

Two key intervals/surfaces are present in deepwater systems: condensed sections andsequence boundaries. Recognizing these surfaces allows us to place deepwater systems with-in a sequence stratigraphic framework for the purposes of correlation, mapping, and char-acterization (Chapter 3).

Condensed sections are relatively thin layers of strata that reflect reduced sedimenta-tion rates (Loutit et al., 1988). In deepwater systems, they can form during (1) relativehighstands of sea level, (2) a major switch in the shallow marine development, or (3) aregional subsidence event with reduced rates of sedimentation.

On seismic profiles, a condensed section exhibits a laterally continuous reflection(s)that drape(s) the underlying sequence (Figure 1-4). The seismic-stratigraphic expression ofa condensed section will differ, depending on its thickness and the frequency of the seis-mic data. The lithologic expression of condensed sections varies greatly both within andbetween basins. These differences reflect different oceanographic/depositional conditions atthe time the condensed section was formed.

Sequence boundaries have both erosional and conformable stratigraphic expressionsin deep water. Where the sequence boundary is erosional, the condensed section andadditional sediments are removed from the underlying sequence (Figure 1-4). The amountof erosion along the sequence boundary varies considerably in the overall deepwater depo-

Figure 1-3. Principal architectural elements of deepwater clastic systems. After Reading andRichards (1994). Reproduced with permission of AAPG.

CH01.QXD 7/1/04 11:15 AM Page 1-5




sitional systems (intraslope versus base of slope). Generally, the greatest amount of erosionoccurs in submarine canyons in the upper slope/outer shelf, where the largest volume ofsediment is removed. The amount of erosion of the slope or intraslope basins varies great-ly. Erosion tends to be focused in a linear downslope direction. In some deepwater sys-tems, the base of slope can be an area of extensive erosion, where major slides that aresourced from the slope erode downward as the depositional gradient decreases (e.g., Fig-ure 1-4).

In most places, the erosional sequence boundary can be traced laterally to a pointwhere the erosion surface ends and grades into a depositional surface directly overlyingthe condensed sections. The depositional surface becomes the “correlative conformity” ofVail et al. (1977). In a vertical profile, shales and sandstones are interbedded, with no ero-sion surface between the sequences. Within intraslope basins, the sequence boundariescan form prominent onlap surfaces, even though there is no erosion.

Regional Controls on Deepwater Systems

The deepwater systems described in this book result from the complex interaction ofmany factors that affect all sedimentary basins. As petroleum geoscientists, our focus is onthe final product or deposit. To properly interpret reservoir characteristics such as sandcontent, sand trend, continuity, connectivity, and reservoir quality, we must be cognizant ofthe processes by which the deposit formed. Several outstanding summary books andpapers have addressed these major controls on the deposition of deepwater systems (Nel-son and Nilsen, 1984; Bouma et al., 1985; Stow et al., 1985; Pickering et al., 1989;

Figure 1-4. Seismic profile across one deepwater depositional sequence (upper Pleistocene) inthe northern deep Gulf of Mexico. Key intervals/surfaces include a condensed section (laterallycontinuous doublet reflections) and erosional sequence boundary. Depositional elements includechannel-fill, levee-overbank, and mass-transport complex. After Weimer (1990). Reprinted withpermission of AAPG.

CH01.QXD 7/1/04 11:15 AM Page 1-6




Richards et al., 1998). We briefly review the important controls below to establish thebackground for the remaining chapters.

Three main influences that control the nature of deepwater depositional systems aretectonics, sediment supply, and sea-level fluctuations (Figure 1-5). Tectonics affect deepwaterdeposition in four ways: (1) where sediments are delivered to the basin, (2) in the geome-try of the basin margin and the basin itself, (3) in the bathymetry of the basin, and (4) inthe way local tectonics affect the distribution of a deepwater system. Hinterland and cli-mate affect the rate, type, and source of sediment supply, and these in turn affect the depo-sitional processes of the basin and the shape, type, and nature of both nearshore and shelfsystems. Sea-level fluctuations can affect deepwater systems through eustatic changes andtectonically induced changes and by varying the supply of clastic input.

A slightly different way to view regional controls on deepwater systems is to recog-nize the influences of the sediment delivery system on reservoir characteristics (Figure 1-6). As exploration and development geoscientists, we deal with the final deposits oflarge, complex, and repeated processes of erosion, transportation, and deposition (lowerright portion of Figure 1-6). Factors that influence the complex sedimentary cycle include(1) the nature of the basin’s drainage in terms of gradients, provenance, sediment type, andclimate; (2) the shelf (widths, gradients, accommodation); (3) the capacity of the shelfedge to store shallow-marine sediments prior to their resedimentation to deep water (i.e.,highstand deltas); (4) the nature of the sediment gravity flows to deep water (large cata-strophic flows from earthquakes, moderate episodic flows from major floods, or small con-tinuous [hyperpycnal] flows from continuous floods); and finally, (5) the rheology of theflows (low-concentration versus high-concentration flows versus sandy-debris flows) andtheir resulting deposits.

Figure 1-5. Diagram illustrating the controls on the development of deepwater clastic deposi-tional systems. After Richards et al. (1998). Reproduced with permission of Elsevier.

CH01.QXD 7/1/04 11:15 AM Page 1-7




Problems in Deepwater Depositional Systems Research: Gaps in Scale Behind Modern and Ancient Data Sets

Bouma et al. (1985) summarized a major barrier in the geologic community’s abilityto compare modern and ancient deepwater systems. The inherent problem is the differentresolution of the technologies used, which causes a major gap in scale (Figure 1-7). Forexample, in the middle 1980s, modern fan studies consisted of shallow-penetration surfi-cial studies focusing on the upper 10 m of the fan. These studies routinely used high-reso-lution seismic data (sparker or small water gun for source), shallow-penetration cores (pis-ton or gravity), and side-scan-looking systems. Modern submarine fans were rarely studiedusing 2D deep-penetration profiles.

In contrast, ancient systems were studied using outcrops and subsurface data sets.Excellent outcrop exposures of turbidite systems may be as high as 100 m and as long as 1 km. Unfortunately, most outcrops worldwide do not have these dimensional characteris-tics (see Weimer et al., 2000b, and many references within).

In fact, two gaps in scale exist in the study of deepwater systems. One gap is betweenmodern fan geometries and multifold seismic data. The second gap is between 3D seismicdata and outcrops and reservoirs.

Since the middle 1980s, the petroleum industry’s extensive use of 3D seismic datasets has largely bridged the gap between modern fan geometries and the geometries ofsubsurface deepwater systems and reservoirs. The extensive use of shallow 3D seismic foroffshore drilling-hazard (e.g., shallow-flow problems, seafloor-stability issues) and reser-voir-analog studies has allowed for the highly accurate imaging of different turbidite ele-ments. Such images are of the same scale as modern seafloor studies. Many companieshave used these kinds of studies for a competitive advantage.

Figure 1-6. Schematic cross section across a margin, illustrating the sediment delivery sys-tem’s influence on reservoir characteristics. After Garfield et al. (1998). Reproduced with permis-sion of AAPG.

CH01.QXD 7/1/04 11:15 AM Page 1-8




The second gap in scale is where most reservoir development problems arise, i.e.,with early water breakthroughs, abrupt pressure drops, and gas coning (Weimer et al.,2000a). Many of the features that control reservoir performance are subseismic in scale.That is, they are beneath the vertical resolution of conventional 3D seismic-reflection data.Features such as lateral bed continuity, vertical bed connectivity, reservoir quality, and netsand content normally cannot be determined from seismic images, yet these are the fea-tures that control fluid flow within the reservoir. Also, small-offset faults and fractures,which are common and critical components of reservoirs, cannot be imaged by conven-tional seismic. Newer seismic techniques, such as spectral deconvolution, are improvingour ability to detect small-scale stratigraphic and structural compartments; however, therestill are natural physical limits to the resolution of seismic images. Because it is so impor-tant that we be aware of these scale issues, Chapters 4–8 describe each deepwater element,integrating all data sets that geoscientists routinely use in their daily workflow.

Historical Evolution of Concepts about Deepwater Systems and the Role of Technology

Fisher (1991) described the important relationships among technology, the evolutionof different scientific and exploration successes, and their effects on improving recoveryefficiencies (Figure 1-8). His main point was that technology plays a dual role in influenc-

Figure 1-7. Graph illustrating different deepwater elements and the relative scale of resolutionfor different data systems. After Bouma et al. (1985) and Morris and Normark (2000). Repro-duced with permission of the GCS–SEPM Foundation.

CH01.QXD 7/1/04 11:15 AM Page 1-9




ing recovery efficiencies. First, as technology improves, so do production techniques. Sec-ond, as technology improves our abilities to image the subsurface, new scientific disci-plines evolve that also affect recoveries.

In a similar way, the geologic community’s understanding of deepwater systems hasalways depended strongly on the technology available at any given time. Since the early1950s, there have been several “paradigm shifts” in the concepts that shaped explorationand development of deepwater reservoirs. Seven major developments are reviewed here, interms of the impact of technological improvements that have driven parallel advances inseveral scientific disciplines. Many of these technological and conceptual developmentsand breakthrough papers are described in greater detail in other chapters in the book.

1) Process sedimentology and facies models for modern depositional systems developedinitially in the 1950s and 1960s. These models tended to focus primarily on deposi-tional systems exposed on land or in marginal-marine environments (i.e., rivers,deltas, and marginal-marine carbonate sediments). Because researchers lacked thetechnology to image and sample the seafloor, modern deepwater systems were largelyignored. However, flume studies by Kuenen and Migliorini (1950) advanced the con-cept of turbidity currents as an important process by which sediment is transportedfrom shallow water to deep water. The first indirect indications of large-scale, natural-ly occurring sediment gravity flows followed the development and distribution ofseafloor communications cables in the late 1800s and early 1900s. Periodic cablebreakages on the deep ocean floor (from 200 to 3500 m of water depth) were recog-nized to have been caused by erosion associated with turbidity currents. Examplescame from the Grand Banks of Newfoundland, offshore eastern Canada (Heezen andEwing, 1952); the Magdelena Fan, offshore Colombia (Heezen, 1956); and theCongo River and continental slope (Heezen et al., 1964).

2) By the 1960s, the concepts of depositional systems began to develop in the generalgeologic community and to replace older ideas about classical layer-cake stratigraphy.Outcrops of deepwater strata were beginning to be recognized and described in detailby such pioneering studies as those by Bouma (1962) and Mutti and Ricci Lucchi(1972) using modern process sedimentology. During this time, two important devel-opments were occurring in seismic-reflection-data acquisition and processing—theuse of a common-depth point (CDP) and the digital recording of data. Their influ-ence was legion and led to extensive collection of seismic data globally. Last, thedevelopment and routine use of side-scan sonar data played an increasingly impor-tant role in the study of modern submarine-fan surfaces.

3) By the middle 1970s, 2D seismic-reflection data were being acquired globally, andseismic stratigraphy was the next major discipline to evolve. Prior to the publicationof seismic stratigraphic concepts in AAPG Memoir 26 (Payton, 1977), seismic-reflec-tion data had been used almost exclusively for structural interpretation. With publi-cation of this landmark book, seismic interpreters began to view 2D seismic in termsof mappable seismic facies that were interpretable as depositional systems. Thisallowed workers to interpret deepwater depositional systems and to interpret thepaleobathymetric setting within a sequence stratigraphic framework (Brown and

CH01.QXD 7/1/04 11:15 AM Page 1-10




Fisher, 1977; Vail et al., 1977). The use of regional 2D seismic data allowed workersto image ancient systems at scales that were not possible with outcrop studies.In addition, “bright-spot” technology began to be used routinely in the early to mid-dle 1970s. Because exploration was focusing primarily on fluvial-deltaic reservoirsglobally, bright-spot technology was applied initially to those kinds of reservoirs.When exploration began to focus more on deepwater reservoirs, this technology wasused extensively for direct hydrocarbon detection—with varying degrees of success(Chapter 2).

4) By the middle 1980s, sequence stratigraphy was evolving with the integration of out-crop data, subsurface data (seismic and wireline logs), and initial attempts at quanti-tative stratigraphic modeling of basin fill. Different depositional elements of deepwa-ter systems were recognized as distinct but predicable facies associations in asequence stratigraphic framework. Outcrops were being reevaluated, in a search for

Figure 1-8. Graph showing the U.S. discovery and recovery efficiencies (dashed line) since1950. Solid line is a normalized curve. Also plotted are the timing of (a) major technology devel-opments (black arrows) and (b) key concepts for deep water (white arrows). Figure is modifiedsignificantly from Fisher (1991).

CH01.QXD 7/1/04 11:16 AM Page 1-11




the stratigraphic features recognized on seismic data. In turn, our understanding ofdetailed stratal architecture from outcrop studies began to influence how fields weredeveloped, because depositional elements were studied to improve our understand-ing of flow-unit continuity.

5) A major breakthrough in the understanding of deepwater deposits came with thedevelopment of and rapid improvement in 3D seismic data. These data, along withparallel advances in water-bottom imaging technology, such as GLORIA side-scansonar, allowed detailed stratigraphic and facies relationships to be characterized inthree dimensions. For the first time, geoscientists had insight into the complex chan-nel-related processes common to deepwater systems. Finally, as 3D seismic databecame less expensive and quicker to acquire, it was integrated into the daily work-flows of geoscientists using computer workstations.

6) Several important trends appeared during the early and middle 1990s. (a) Politically,many global deepwater basins were opened to exploration in such diverse settings asNigeria, Angola, the Nile Delta, Brazil, Brunei, and Kutei. (b) Routine acquisition andinterpretation of 3D seismic data from these basins generated remarkably detailedimages of the deepwater depositional elements. (c) As a consequence, many of thearguments about where deepwater systems fit within a stratigraphic framework beganto disappear. Instead, industry focused on seismic- to subseismic-scale problemsassociated with exploration and production. The discipline we informally call “3Dseismic stratigraphy” began to emerge. (d) All of the above observations were leadingresearchers to reexamine some of the fundamental concepts about sedimentaryprocesses associated with deepwater systems. Research began to focus on numericmodeling of deepwater processes, as well as on experimentally generating sedimentgravity flows in large flumes. A better understanding of the physics of sediment grav-ity flows has evolved and has influenced the interpretation of lithofacies, which inturn impacts reservoir description and development. (e) Industry increasingly hasbeen using 4D seismic data to image the movement of fluids in reservoirs. Industry isbeginning to develop different techniques for collecting these sorts of repeated 3Ddata, with minimal variation in acquisition and processing. Multicomponent seismicis also being developed, although its application to deep-marine settings has beenextremely limited.

7) Currently (early 2004), industry is in a phase of major capital investment to developmany of the new deepwater discoveries of the past several years. Most of the reser-voir problems occur at subseismic scale. Thus, significant investment in technologyand research is targeted to improve the accuracy of 3D earth models for predictingand managing fluid recovery. Construction of such models requires the integration ofall available technologies for defining the distribution of lithofacies and flow units forfluid-flow modeling.

CH01.QXD 7/1/04 11:16 AM Page 1-12




Short-course Organization

This course is organized to start at the regional scale, then focus on local- and reser-voir-scale issues, and finish at the regional scale, summarizing the six components of thepetroleum systems.

Chapter 2 gives an overview of recent deepwater drilling trends and results and theregional geology of deepwater settings.

Chapter 3 presents the regional sequence stratigraphic framework within whichdeepwater systems develop.

Chapters 4–8 address the main reservoir elements in deepwater settings: channelsand their sedimentary fill (Chapter 4), levees-overbanks (Chapter 5), sheets (Chapter 6),mass-transport complexes and slides (Chapter 7), and hybrid-type deepwater reservoirsand the pitfalls in interpreting deepwater deposits (Chapter 8).

Chapter 9 summarizes the many kinds of traps in deepwater settings. Chapter 10 summarizes the remaining elements of the petroleum systems: seals,

source rocks, generation and migration, and timing. Time and space do not allow us to cover all the topics that are important to an

understanding of the petroleum systems of deepwater settings. These topics include sedi-mentary processes, reservoir characterization, reservoir modeling, biostratigraphy of deep-water systems, and the occurrences of ore deposits in deepwater settings. Instead, thesetopics will be summarized in a forthcoming companion book by Weimer and Slatt.

Appendix 1-A: Definitions of Deepwater Elements Used in this Book

Depositional lobes (Mutti and Normark, 1987, 1991): “Lobes are areas of sand deposition . . . inmodern systems they lie immediately downslope from the main channel. In ancient systems [they] arerepresented by roughly tabular, nonchannelized bodies that have individual thicknesses, generally of 3–15m. Each lobe is made up of relatively thick and coarse sandstone beds that are generally parallel sidedeven at the scale of large exposures.”

Sheet (Mahaffie, 1994): “Sheet sands most closely resemble . . . fan lobe deposits and are characterizedin outcrop . . . by their laterally-continuous, tabular external geometries. Differences in internal architec-tures allow for further subdivision . . . into two distinct subunits: amalgamated sheets and layered sheets.Amalgamated sheets . . . are characterized by high net:gross comprising stacked assemblages of top-absentBouma sequences. Layered sheets are characterized by lower net:gross sand percentages (with) completeor base-absent Bouma A sequences.”

Channel (Mutti and Normark, 1991): “[Channels] are elongate negative-relief features produced and/ormaintained by turbidity-current flow . . . (they) represent relatively long-term pathways for sedimenttransport. Channel shape and position within in a turbidite system are controlled by depositional process-es . . . or erosional downcutting. . . . Channel relief can be dominantly erosional or depositional in originor can result from a combination of both processes.”

CH01.QXD 7/1/04 11:16 AM Page 1-13




Overbank (Mutti and Normark, 1991): “Overbank deposits are generally fine-grained thin-bedded tur-bidite sediments that can be laterally extensive and are adjacent to the main channels in a turbidite system. . . [and consist of] two parts: (1) those with levee relief, where overbank deposition along the margins ofan active channel has constructed relief, and (2) the most distal parts of an overbank environment withoutmajor relief.”

Thin beds (Shew et al., 1994): “[Thin beds] are interpreted to include levee, interchannel, and outerfan/fringe deposits . . . [and are] composed of very fine sands and/or silt and contain abundant ripple bed-ding, pinch-and-swell structures, some convolute bedding, minor bioturbation, and mostly graded beds.”

Mass-transport complex (Weimer, 1989): “[Mass-transport complexes are] sediments that occur atthe base of sequences and are overlain and/or onlapped by channel and levee sediments. They commonlyoverlie an erosional base upfan, becoming mounded downfan, are externally mounded in shape, andpinch out laterally. . . . Seismic facies (are) hummocky and mounded reflections with poor to fair continu-ity and variable amplitude.” This term is primarily a seismic facies description.

Slides (Jackson, 1997): “[Slides are] a mass movement or descent from failure of earth . . . or rock undershear stress along one or several surfaces. . . . The moving mass may or may not be greatly deformed, andmovement may be rotational or planar.”

Condensed sections (Loutit et al., 1988): “[Condensed sections] are thin marine stratigraphic unitsconsisting of pelagic to hemipelagic sediments characterized by very low sedimentation rates. They areareally most extensive at the time of maximum regional transgression of the shoreline.”

References

Bouma, A. H., 1962, Sedimentology of some flysch deposits: A graphic approach tofacies interpretation: Amsterdam, Elsevier.

Bouma, A.H., W. R. Normark, and N. E. Barnes, 1985, COMFAN: Needs and initialresults, in A. H. Bouma, W. R. Normark, and N. E. Barnes, eds, Submarine fans andrelated turbidite systems: New York, Springer-Verlag, 7–12.

Brown, L. F. Jr., and W. R. Fisher, 1977, Seismic-stratigraphic interpretation of deposi-tional systems: Examples from Brazilian rift and pull-apart basins: AAPG Memoir 26,213–248.

Chapin, M. A., P. Davies, J. L. Gibson, and H. S. Pettingill, 1994, Reservoir architectureof turbidite sheet sandstones in laterally extensive outcrops, Ross Formation, westernIreland, in P. Weimer, A. H. Bouma, and B. F. Perkins, eds., Submarine fans and tur-bidite systems: Gulf Coast Section–SEPM Foundation 15th Annual Research Confer-ence, 53–68.

Elliott, T., 1998, A renaissance in the analysis of turbidite systems: Implications forreservoir development and management: EAGE/AAPG Research Conference, Devel-oping and managing turbidite reservoirs: Case histories and experiences: Almeria,Spain, October 1–8.

Fisher, W. R., 1991, Future supply potential of U.S. oil and natural gas: The LeadingEdge, 11, 15–21.

CH01.QXD 7/1/04 11:16 AM Page 1-14




Garfield, T. R., D. C. Jennette, F. J. Goulding, and D. K. Sickafoose, 1998, An integratedapproach to deepwater reservoir prediction: AAPG International Conference andExhibition, Expanded Abstracts volume, 278–279.

Heezen, B. C., 1956, Corrientes de turbidez del Río Magdalena: Boletín de la SociedadGeográfica de Colombia, 51–52, 135–143.

Heezen, B. C., and M. H. Ewing, 1952, Turbidity currents and submarine slumps, andthe 1929 Grand Banks earthquake: American Journal of Science, 250, 849–873.

Heezen, B. C., R. J. Menzies, E. D. Schneider, M. H. Ewing, and N. C. L. Grainelli,1964, Congo submarine canyon: AAPG Bulletin, 48, 1126–1149.

Jackson, J. A., ed., 1997, Glossary of geology, fourth edition: Alexandria, Virginia, Amer-ican Geological Institute, 784 p.

Kuenen, P. H., and C. I. Migliorini, 1950, Turbidity currents as a cause of graded bed-ding: Journal of Geology, 58, 91–127.

Loutit, T. S., J. Hardenbol, P. R. Vail, and G. R. Baum, 1988, Condensed sections: Thekey to age determination and correlation of continental margin sequences, in C. K.Wilgus, B. S. Hastings, C. A. Ross, H. W. Posamentier, J. Van Wagoner, and C. G. St. C. Kendall, eds., Sea-level changes: An integrated approach: SEPM Special Publi-cation 42, 183–213.

Mahaffie, M. J., 1994, Reservoir classification for turbidite intervals at the Mars discov-ery, Mississippi canyon 807, Gulf of Mexico, in P. Weimer, A. H. Bouma, and B. F.Perkins, eds., Submarine fans and turbidite systems: Gulf Coast Section–SEPMFoundation 15th Annual Research Conference, 233–244.

Morris, William R., and William R. Normark, 2000, Scaling, sedimentologic and geo-metric criteria for comparing modern and ancient sandy turbidite elements, in P.Weimer, R. M. Slatt, J. L. Coleman, N. Rosen, C. H. Nelson, A. H. Bouma, M.Styzen, and D. T. Lawrence, eds., 2000, Global deep-water reservoirs: Gulf CoastSection–SEPM Foundation Bob F. Perkins 20th Annual Research Conference,1104 p.

Mutti, E., 1985, Turbidite systems and their relations to depositional sequences, in G. G.Zuffa, ed., Provenance of arenites: Dordrecht, Netherlands, Reidel, 65–93.

Mutti, E. and W. R. Normark, 1987, Comparing examples of modern and ancient tur-bidite systems: Problems and concepts, in J. K. Leggett and G. G. Zuffa, eds., Marineclastic sedimentology: London, Graham and Trotman, 1–38.

Mutti, E. and Normark, W. R., 1991, An integrated approach to the study of turbiditesystems, in P. Weimer and M. H. Link, eds, Seismic facies and sedimentary processesof submarine fans and turbidite systems: New York, Springer-Verlag, 75–106.

Mutti, E., and F. Ricci Lucchi, 1972, Le torbiditi dell’Appennine settentrionale: Intro-duzione all’analisi di facies: Memorie Societa Geologica Italiana, 11, 161–199.

Nelson, C. H., and T. H. Nilsen, 1984, Modern and ancient deep-sea fan sedimentation:SEPM Short Course Notes No. 14.

CH01.QXD 7/1/04 11:16 AM Page 1-15




Payton, C. E., ed., 1977, Seismic stratigraphy-applications to hydrocarbon exploration:AAPG Memoir 26.

Pickering, K. T., R. N. Hiscott, and F. J. Hein, 1989, Deep marine environments: Clasticsedimentation and tectonics: Boston, Unwin Hyman Ltd.

Reading, H. G., and M. Richards, 1994, Turbidite systems in deep-water basin marginsclassified by grain size and feeder system: AAPG Bulletin, 78, 792–822.

Richards, M., M. Bowman, and H. Reading, 1998, Submarine-fan systems I: Characteri-zation and stratigraphic prediction: Marine and Petroleum Geology, 15, 687–717.

Richards, M., and M. Bowman, 1998, Submarine fans and related depositional systemsII: Variability in reservoir architecture and wireline log character: Marine and Petro-leum Geology, 15, 821–839.

Shew, R. D., D. R. Rollins, G. M. Tiller, C. J. Hackbarth, and C. D. White, 1994, Charac-terization and modeling of thin-bedded turbidite deposits from Gulf of Mexico usingdetailed subsurface and analog data, in P. Weimer, A. H. Bouma, and B. F. Perkins,eds., Submarine fans and turbidite systems: Gulf Coast Section–SEPM Foundation15th Annual Research Conference, 327–334.

Stelting, C. E., A. H. Bouma, and C. G. Stone, 2000, Fine-grained turbidite systems:Overview, in A. H Bouma and C. G. Stone, eds., Fine-grained turbidite systems:AAPG Memoir 72 and SEPM Special Publication No. 68, 1–8.

Stow, D. A. V., D. G. Howell, and C. H. Nelson, 1985, Sedimentary, tectonics, and sea-level controls, in A. H. Bouma, W. R. Normark, and N. E. Barnes, eds, Submarinefans and related turbidite systems: New York, Springer-Verlag, 15–22.

Vail, P. R., et al., 1977, Seismic stratigraphy and global changes in sea level, parts 1–11:AAPG Memoir 26, 51–212.

Weimer, P., 1990, Sequence stratigraphy, seismic geometries, and depositional history ofthe Mississippi Fan, deep Gulf of Mexico: AAPG Bulletin, 74, 425–453.

Weimer, P., R. M. Slatt, P. Dromgoole, M. Bowman, and A. Leonard, 2000a, Developingand managing turbidite reservoirs: Case histories and experiences—Results from theAAPG/EAGE Research conference: AAPG Bulletin, 84, 453–464.

Weimer, P., R. M. Slatt, J. L. Coleman, N. Rosen, C. H. Nelson, A. H. Bouma, M. Styzen,and D. T. Lawrence, eds., 2000b, Global deepwater reservoirs: Gulf Coast Section–SEPM Foundation Bob F. Perkins 20th Annual Research Conference.

CH01.QXD 7/1/04 11:16 AM Page 1-16


1_introduction to deepwater systems- definitions_and_concepts

Documents