QCL/Equinor Joint Research Projects

Project Researchers

Dallas Dunlap
Interpreter, Visualization Specialist
dallas.dunlap@beg.utexas.edu
512-475-6184

Dr. Yanlei Dong
Visiting Scientist from China University of Petroleum, Beijing

Emily Finkelman
B.S. Candidate

Dr. Vishal Maharaj
Employed with Marathon Oil

Damian Markez
M.S., employed with Shell

Dr. Kurtus Woolf
Employed with Newfield Energy

Pre-Tertiary Gulf of Mexico Project: Sub-Mad Dog Cretaceous Study

Talks

• Lesli Wood, Damian Markez, and Yanlei Dong, 2013: Structural framework and seismic geomorphology of the pre-Miocene beneath the Mad Dog Area, GOM Belt
  • (.ppt)
• Damian Markez, Lesli Wood and Dallas Dunlap, 2012: What Lies Beneath: Accommodation history and seismic geomorphology of the Cretaceous beneath the Mad Dog Area, Gulf of Mexico
  • (.ppt)

Lobes Project: Lobster Field Subsurface Study

Subsurface Channel and Lobe Architecture Studies in a Slope Mini-basin, Lobster Area, Central Gulf of Mexico.

Depositional Setting—Pertinent Criteria

• Structural Setting: Deep and shallow salt, growth faulting. Compressional folding.
• Age: Miocene to present
• Critical Parameters: Changing rates of accommodation. Varying degrees of confinement of flows. Opening and closing of sediment gateways.
• Sediment Conditions: High rates for deepwater. Proximal to the central GOM paleo-Mississippi sources. Late stage mass transport deposition.
• Source Systems: Paleo-Mississippi River and Delta.
• Main Features: Varying types of lobe/channel relationships. Varying sizes and shapes of lobe development. High resolution of channel to lobe transitions in shallow data. ~30 well logs for assessing log motif and net:gross. Fifteen years of production data.
• Data: Well and production data provided by Marathon Oil. Seismic data provided by PGS.

Summary of Geologic Setting

• Basin type: Unconfined to confined basin
• Setting: Modern upper slope

The Lobster field area, also known as Ewing Bank block number 873 was discovered in the Gulf of Mexico in 1991. It produces from a stacked series of six Pliocene-age distal turbidite sand lobes. The west side of the basin is more sand-rick amalgamated channels and lobes, while the east side of the basin has a higher shale content in predominately overbank deposits (Uland, et al, 1997). Oil gravities are 18 to 23 API. Sand porosities range from 25 to 30% and permeability is greater than 1 darcey (Edman and Burk, 1996). Initial work shows that many of the lobes need to be subdivided into smaller production compartments.

The Lobster and Lobster N. Field reservoirs are a series of deep water lobes deposited from the north into a salt withdrawal mini-basin subsiding at varying rates both spatially and temporally. These deep water lobes appear, based upon log data, to be composed of sand, silt and clay, and likely contain debris sized material interbedded in their strata. The deep water sediment gravity flows that form these lobate deposits often start as channelized flows but will alternate between channelized and non-channelized (sheets) depending on the height of the flow relative to the slope and surrounding topography. The height of the flow is a function of several variables including the mix of lithologies and density of the flow itself.

Lobate features within the Lobster mini-basin show a variety of degrees of channelization and non-channelization. Their lengths (distance from basin edge origination point to distal lobe edge) vary and the distance from their channel-lobe transition to lobe termination varies. Their widths vary spatially and their morphology appears to vary temporally. All of these differences suggest highly variable reservoir character between lobe events, as well as varying degrees of spatial connectivity (horizontal) and temporal connectivity (vertical). Production data available to the research team confirm that the eastern side of the basin is isolated from the western side of the basin.

Sands seldom if ever truly occur as sheets in deep water settings. Rather they are composed of thousands of small lobate gravity flows (of varying geometries) that are amalgamated into what appears as a sheet.  However they contain many baffles to flow. The degree to which these small-scale baffles connect dictate the flow performance. This is not a situation that is unique to any one setting, but an observation broadly applicable to most deep water lobe deposits. The Lobster settings offers a chance to examine a range of lobe types, characterizing each one and its relationship to its nearest neighbor (above and below) and assessing the degree of connectivity within and between lobe types. Observations will be applicable to systems ranging from Recent to the Cretaceous deposits in the Gulf of Mexico, and other deep water basins along the US Atlantic and Pacific margins.

Original field reservoir model run using original five exploration wells. From Ulaub, et al., 1997.

Original field reservoir model of Ulaub et al. (1997) run using eight wells, integrating production observations and geochemical data collected up to that point.

Original porosity grid for the Lobster field, used by Ulaub et al., (1997) to generate initial reservoir models.

Quantitative Character of the System

Above: Lobe length versus width graph for the lobe complexes show the increased size of the lobes composing the older Cali Lobe Complex. Bar graph shows changes in lobe area, with a steady decrease in lobe size over time. Lower image is a schematic illustrtation of the Cali and Bartley complexes and their stratigraphic relationships.

The Lobster mini-basin is a proximal slope fill composed of a series of Lower Pliocene-age stacked amalgamated turbidite lobes and leveed channel systems deposited during the 4.01 my global lowstand of sea level. Sands are broken into seven lobes in log correlation panels; the 10, 20, 30, 40, 70, 80 and 90. In the seismic, these lobes stack to form two lobe complexes the basinward Cali Complex and the more proximal Bartley Complex. Nearly 100% of the log penerations occur in the Bartley Complex in lobes 10, 20, 30, 40, 70, 80 and 90. The nature of these "lobe complexes" vary from deeply channelized along the western margins of the mini-basin to more lobate in the eastern side of the basin. Length and width data collected on these lobes. In both complexes, lobes shingle to the east in response to an eastward located normal fault, and individual lobes of each complex backstep toward the northern basin margin and become aerially smaller. In each lobe complex, the oldest and stratigraphically deepest lobe is largest. The thickest deposit of lobes is laid down approximately 40% of the distance into the basin, a phenomena observed in experimental mini-basins as well (see Maharaj, Experimental Modeling Results).

Maharaj, Experimental Modeling Results

Talks

• Vishal Maharaj, James Buttles, David Mohrig, and Lesli Wood: Experimental observations on submarine deepwater sedimentation in and around subsiding minibasins
  • (.pptx)
  • (.ppt)
  • Movie, MVI_1995 (.mov)
  • Movie, MVI_2076 (.mov)
  • Movie, MVI_2077 (.mov)
• Lesli Wood and Vishal Maharaj: Insights on unconfined and confined minibasins fills from experimental observations applied to real-world data
  • (.pptx)
  • (.ppt)
  • Movie, Underwater_Avalanche (.mov)

Publications

• Maharaj, V., Dissertation 2012: The Effects of Confining Minibasin Topography on Turbidity Current Dynamics and Deposit Architecture
  • (.pdf, 27 MB)

Pertinent Literature Summary—Detailed discussion of pertinent literature, from Maharaj, 2012, Chapter 3.

Click here to download this discussion list in PDF format.

General Review and Principles

These papers are selected from a much larger bibliography on deepwater systems and summarized below, as a "Go-To" selection of key papers to understand the key aspects of deepwater environments and how sedimentary processes (skewed toward turbidity current processes) are inherently different from processes in shallow-marine and terrestrial environments. Key controls that affect sedimentation in the deepwater environment are also discussed, and the associated depositional elements.

Pickering, K. T., R. N. Hiscott, and F. J. Hein, 1989, Deep marine environments; clastic sedimentation and tectonics: United Kingdom, Unwin Hyman: London, United Kingdom.

The authors aim to fill a gap in literature pertaining to deep-sea environments, and provide an integrated treatment of process, environments and plate tectonic controls in both modern and ancient deep marine settings. The book describes the processes of transport and deposition, the facies that are produced and the major factors that control sedimentation and sequences. Additionally, the main environmental elements that make up the deep sea, including slope aprons, slope basins, submarine canyons, valleys, submarine fans, sheet systems and contourite drifts, are described using case studies.

Bouma, A. H., 2004, Key controls on the characteristics of turbidite systems: Geological Society, London, Special Publications, v. 222, p. 9–22.

Bouma focuses on the four main controls (tectonics, climate, sedimentary characteristics and processes, and sea-level fluctuations) that commonly interact with each other, and results in a wide variety of basin types and shapes, timing of transport within the sequence stratigraphy framework, transport and depositional processes, grain size ranges, and distribution of sediment within a deepwater sedimentary basin. He recognizes two end members of turbidite systems: coarse-grained/sand-rich and fine-grained/mud-rich, and describes the characteristics of basin types (unconfined vs. confined) and their key sedimentary characteristics resulting from the main controls previously mentioned.

Meiburg, E., and B. Kneller, 2009, Turbidity currents and their deposits: Annual Review of Fluid Mechanics, v. 42, p. 135–156.

This article is one of the more recent comprehensive publications that outlines the current state of our understanding of turbidity currents and the deposits they form. Emphasis is placed on the nature of turbidity currents in the global sediment cycle, their significance in environmental processes, key findings from experimental and field studies, and their influence in determining the quality of hydrocarbon reservoirs.

Sequence Stratigraphic Concepts and Accommodation

Sequence stratigraphic concepts (Mitchum, 1985; Mutti, 1985; Vail, 1987; Posamentier et al., 1988; Normark et al., 1993; 1998) add further emphasis to the study of turbidite systems and, which highlight the relationships between eustasy-driven changes and turbidite deposition. Within confined slope settings, other authors (e.g. downplay the role of sequence stratigraphic concepts in deep-water sedimentation, where local influences predominate (e.g. earthquakes, tectonic/ depositional oversteepening, depositional/ hydrostatic/ glacial loading, cyclones, tsunamis, volcanic activity, salt/ shale movement, among others).

The concept of sediment 'accommodation' describes the amount of space that is available for sediments to fill, and it is measured as the distance between base level and the depositional surface (Jervey, 1988; Catuneanu, 2006). It is generally accepted that the ultimate, large-scale, controls influencing deepwater depositional systems on continental margins are sediment supply, regional basin tectonics and relative changes in sea level (Mutti & Normark, 1991; Posamentier et al., 1988; Posamentier & Vail, 1988; Reading & Richards, 1994; Vail et al., 1977). The interplay among these controls results in an infinite amount of scenarios for deepwater fill and the degree of influence of the individual components are difficult to discern.

Catuneanu, O., 2006, Principles of Sequence Stratigraphy: Developments in Sedimentology: Amsterdam, Elsevier.

Jervey, M. T., 1988, Quantitative geological modeling of siliciclastic rock sequences and their seismic expression: Special Publication—Society of Economic Paleontologists and Mineralogists, v. 42, p. 47–69.

Posamentier, H. W., M. T. Jervey, and P. R. Vail, 1988, Eustatic controls on clastic deposition; I, Conceptual framework: Special Publication—Society of Economic Paleontologists and Mineralogists, v. 42, p. 109–124.

Posamentier, H. W., and P. R. Vail, 1988, Eustatic controls on clastic deposition; II, Sequence and systems tract models: Special Publication—Society of Economic Paleontologists and Mineralogists, v. 42, p. 125–154.

Mitchum, R. M., Jr., 1985, Seismic stratigraphic expression of submarine fans: AAPG Memoir, v. 39, p. 117–136.

Mutti, E., and W. R. Normark, 1991, An integrated approach to the study of turbidite systems Frontiers in sedimentary geology: United States, Springer-Verlag : New York, NY, United States, p. 75–106.

Normark, W. R., H. Posamentier, and E. Mutti, 1993, Turbidite systems; state of the art and future directions: Reviews of Geophysics, v. 31, p. 91–116.

Normark, W. R., D. J. W. Piper, and R. N. Hiscott, 1998, Sea level controls on the textural characteristics and depositional architecture of the Hueneme and associated submarine fan systems, Santa Monica Basin, California: Sedimentology, v. 45, p. 53–70.

Vail, P. R., R. M. Mitchum, Jr., and S. Thompson, III, 1977, Seismic stratigraphy and global changes of sea level; Part 3, Relative changes of sea level from coastal onlap: Memoir—American Association of Petroleum Geologists, p. 63–81.

Sediment Flux, Caliber and Transport

This section describes results from experimental and field observations related to studies that investigate the influence of sediment caliber on the transport capabilities of turbidity currents.

Al Ja'Aidi, O. S., W. D. McCaffrey, and B. C. Kneller, 2004, Factors influencing the deposit geometry of experimental turbidity currents: implications for sand-body architecture in confined basins: Geological Society, London, Special Publications, v. 222, p. 45–58.

This paper outlines the effect of flow volume, flow density and grain-size distribution on the transport efficiency of turbidity currents and the nature of deposit characteristics. Deposits from large-volume flows are elongate, while those of fines-rich flows are broad. Increase in flow density increases the initial potential energy of the flow, thereby increasing the effective runout distance. However, a threshold sediment concentration of 13% by mass results in a reversal of the geometric trend of deposit elongation, possibly due to turbulence suppression. An increase in the proportion of fines leads to maintenance of negative buoyancy and decreases the settling velocity of the coarser fraction within the flow. In a second set of experiments, the influence of flow efficiency on the interaction with obstructing topography was investigated. It was found that increasing the proportion of fines increased the flow efficiency, which resulted in an increase in the proportion of sediment reaching the obstructing topography and the proportion of sediment able to surmount the topography. Implications of these occurrences for trapping sediment from inbound turbidity currents by confining topography are then discussed.

Covault, J. A., E. Shelef, M. Traer, S. M. Hubbard, B. W. Romans, and A. Fildani, Deep-Water Channel Run-Out Length: Insights from Seafloor Geomorphology: Journal of Sedimentary Research, v. 82, p. 25–40.

This paper gives insight into seafloor channel processes, morphologic products, and scaling relationships, which can be broadly applied to predicting ancient subsurface and outcropping deep-water stratigraphic sequences. Their comparative analysis suggests that knowledge of the thickness of an ancient basin-margin stratigraphic sequence can be employed in order to generally predict the basinward extent of a paleo-canyon-and-channel system and underlying depositional fan. The application also potentially works in reverse: intimate knowledge of the deep-water component of a continental margin or basin margin can facilitate understanding of up-depositional-dip stratigraphic architectures where data might be lacking.

Lamb, M. P., T. Hickson, J. G. Marr, B. Sheets, C. Paola, and G. Parker, 2004, Surging versus continuous turbidity currents; flow dynamics and deposits in an experimental intraslope minibasin: Journal of Sedimentary Research, v. 74, p. 148–155.

This article focuses on the dynamics and deposits of both surging and continuous turbidity currents flowing into a model mini-basin. In the analysis, the authors employed the use of a Ponding Index to quantitatively illustrate the differences between the deposits formed from each type of event. They suggest that the differences between the deposits are likely due to the relative proportion of head to body of the flows, where (1) the continuous flows led to the establishment of a quasi-stead dammed turbidity current, which resulted in uniform deposition with a low Ponding Index, while (2) the surge events were sufficiently small to be contained by the basin, and deposited "ponded" deposits that were characterized by relatively higher Ponding Indices. Further implications for interpreting the ability of a basin to trap sediment from each type of flow are discussed, and the implications for interpreting the deposit geometries of single events versus cumulative events are described.

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

Reading and Richards (1994) sub-divide continental slopes into 12 classes based on grain-size (mud-rich, mud/ sand-rich, sand-rich and gravel-rich) and feeder system configuration (point-sourced, line-source and multiple sourced). They suggest that the size and stability of channels and the organization of the depositional sequences decreases toward a linear source as does the length:width ratio of the system. As grain size increases, so does slope gradient, persistence of channel systems, and tendency for channels to migrate. As grain size diminishes, there is an increase in the size of the source area, the size of the depositional system, the down-current length, the persistence and size of flows, fan channels, channel-levee systems, and in the tendency to meander and for major slumps and sheet sands to reach the lower fan and basin plain.

Richards, M., M. Bowman, and H. Reading, 1998, Submarine-fan systems; I, Characterization and stratigraphic prediction: Marine and Petroleum Geology, v. 15, p. 689–717.

Richards et al. (1998) ascribe predictive value to the classification scheme by Reading and Richards (1998) and describe a method for reservoir description and prediction in three investigative stages that include basin screening, fan delineation and fan characterization.

Unconfined Systems and Models

Unconfined deep-water depositional models are ubiquitous in the literature and are built on the premise that submarine deep-water elements form major hydrocarbon reservoirs in continental margin basins. Such deep-water elements may include canyons, channels, levees, lobes (channelized and depositional), slumps and slides. The successful exploration and exploitation of these resources have resulted in a myriad of studies that seek to understand the geometry, continuity and stacking patterns of sediment gravity flow deposits on a range of scales – from pore, bed and bedset properties (reservoir scale) to complexes and complex sets. Below are key studies that form the foundation for understanding the unconfined deepwater environment.

Mutti, E., and G. Ghibaudo, 1972, Un esempio di torbiditi di conoide sottomarina esterna: le Arenarie di San Salvatore (Formazione di Bobbio, Miocene): Matematiche e Naturali, v. 4, 40 p.

Mutti, E., and F. Ricci Lucchi, 1972, Le torbiditi dell'Appennino settentrionale: Introduzione all' analisi di facies: Societa Geologica Italiana, v. 11, p. 161–199.

Mutti and Ghibaudo (1972) and Mutti and Ricci Lucchi (1972) proposed a model for ancient turbidite systems where facies associations were interpreted in terms of specific deep-water fan environments for the first time. Mutti and Ghibaudo (1972) emphasized the depositional similarities between fluvial-dominated deltas and deep-water fans, by suggesting a direct comparison between deltaic channels and their resultant mouth bars to turbidite channels and their resultant lobes. Mutti and Ricci Lucchi (1972) offered a more comprehensive model where turbidite facies associations were interpreted in terms of slope, fan and basin plain environments, and specific facies associations were interpreted to be diagnostic of inner, middle and outer deep-water fan environments. Mutti and Ricci Lucchi (1972) also stressed the overall progradational character of many ancient submarine fan systems and emphasized the thinning- and fining-upward nature of channel-fill sequences, which contrast with the thickening- and coarsening-upward character of turbidite sand lobes.

Normark, W. R., 1970, Growth patterns of deep-sea fans: American Association of Petroleum Geologists Bulletin, v. 54, p. 2170–2195.

Normark (1970) presented the first widely used model of submarine-fan growth from the California Borderland and offshore Baja California, which inspired subsequent studies regarding the development of modern and ancient turbidite systems (e.g., Mutti and Ricci Lucchi, 1972; Walker, 1978; Normark, 1978; Normark et al., 1979; Normark and Hess, 1980; Nilsen, 1980; Nardin, 1983; Mutti, 1985; Mutti and Normark, 1991; Fildani and Normark, 2004). Normark's (1970) groundbreaking work introduced the turbidite-system growth-pattern concept, which was defined as the overall system morphology related to the origin and recent history of canyons and channels on the present seafloor. He emphasized the importance of depositional bulges or suprafans developed at the terminus of fan valleys.

Nelson, C. H., and T. H. Nilsen, 1976, Depositional trends of modern and ancient deep-sea fans Benchmark papers in geology, v. 24: United States, Dowden, Hutchinson and Ross, Inc.: Stroudsburg, Pa., United States, p. 388–410.

Mutti, E., and W. R. Normark, 1987, Comparing examples of modern and ancient turbidite systems; problems and concepts: United Kingdom, Graham and Trotman : London, United Kingdom, p. 1–38.

Mutti and Normark (1987) recognized four main types of turbidite basins. They emphasize that the volume of sediment and the long-term stability of the receiving basin primarily control the morphology and internal facies associations of submarine fans.

Mutti, E., and W. R. Normark, 1991, An integrated approach to the study of turbidite systems Frontiers in sedimentary geology: United States, Springer-Verlag : New York, NY, United States, p. 75–106.

Along with eustasy and tectonism, Mutti and Normark (1991) emphasize the composition and volume of turbidity currents as well as the basin type and configuration as primary factors controlling the geometry and facies patterns of turbidite systems.

Confined Systems and Models

Confinement is a term that has been historically associated with the relationship between deep-water currents and the topography with which they interact. Associated with this definition is primarily qualitative measure that researchers have used to describe the degree of structural confinement in a particular setting. What appears to be poorly understood and not adequately addressed in published work is the relationship between the magnitude of 3-D basin confinement relative to the size and efficiency of currents supplying sediment to the basin. The papers below outline how confined deepwater systems are currently characterized in the present-day literature, and some of the implications for interpreting sedimentary processes and deposit characteristics on topographically-complex slopes.

Lomas, S. A., and P. Joseph, 2004, Confined turbidite systems: Geological Society, London, Special Publications, v. 222, p. 1–7.

This article is a preface to a series of papers that address confined turbidite systems in modern and ancient settings, all of which are relevant to this topic. Recent studies have emphasized the fundamental influence of seafloor topography on the growth and morphology of submarine 'fans': in many turbidite systems and turbidite hydrocarbon reservoirs, depositional system development has been moderately to strongly confined by pre-existing bounding slopes. Lomas and Joseph (2004) favor a general definition of confinement to describe situations where sediment gravity flows and their deposits are appreciably affected by the presence of significant basin-floor topography, but without the connotation of complete containment.

Steffens, G. S., E. K. Biegert, H. S. Sumner, and D. Bird, 2003, Quantitative bathymetric analyses of selected deepwater siliciclastic margins; receiving basin configurations for deepwater fan systems: Marine and Petroleum Geology, v. 20, p. 547–561.

This comparative bathymetric analysis of four siliciclastic continental margins reveal that there appears to be significant differences in receiving basin configurations between salt-based and shale-based continental margins in the Gulf of Mexico, Angola, Nigeria, and NW Borneo, especially in the type, amount, and distribution of accommodation. They find that ponded accommodation is more prevalent in margins controlled by salt tectonics. Shale-based systems however are suggested to be more prone to bypass on the upper to mid slope than salt-based systems. Evidence for this is found in linear grade trend analyses where large below-grade areas (sinks) are pervasive on the upper and mid slope of salt-based systems for deepwater sediment to accumulate, while shale-based systems show extensive above-grade highs across the entire slope. Ponded accommodation trends and drainage analyses also demonstrate that shale-based systems are more susceptible to extensive bypass than salt-based systems.

Smith, R., 2004, Silled sub-basins to connected tortuous corridors: sediment distribution systems on topographically complex sub-aqueous slopes: Geological Society, London, Special Publications, v. 222, p. 23–43.

Smith (2004) describes two end members of topographically complex slopes as either cascades of silled sub-basins, or connected, tortuous corridors. In the first scenario, a downslope sill hinders downslope flow, or at least the basal, sandy portions of sediment gravity flows until deposition reduces the relief sufficiently to facilitate downslope "spilling." For the second scenario, flows tend to avoid bathymetric obstacles, and follow a laterally confined, continuous tortuous path down the slope. He proposes that fill patterns and reservoir architecture are controlled by the volume and flow properties of the sediment supply, the relative scale of the receiving basin space and the flows, the relative rates of basin subsidence, and the infilling depositional processes.

Covault, J. A., 2009, Growth patterns of deep-sea fans revisited; turbidite-system morphology in confined basins, examples from the California Borderland, in B. W. Romans, ed., Marine Geology, Netherlands, Elsevier : Amsterdam, Netherlands, p. 51–66.

Covault and Romans (2009) quantified turbidite-system gross morphologies using an extensive grid of seismic data and characterized turbidite systems according to volume, area, maximum thickness, length and width. Their results show that for turbidite systems that supplying a large enough volume of sediment to be confined by their basin margins were unable to areally expand and, subsequent turbidite deposition thickened the systems. Insufficient volumes of sediment to extend systems to their receiving-basin margins however resulted in thinner deposits. They suggest that the growth and morphologies of turbidite systems in confined receiving basins, such as California borderland and the western Gulf of Mexico slope, are greatly influenced by relatively smaller volumes of sediment supplied and receiving-basin confinement. They are distinctively different from voluminous, finer-grained, unconfined systems that are unrestricted by basin margins, and as a result, they grow to be distinctively areally extensive in large ocean basins.

Mini-basins and Their Fill

Established models of how mini-basins fill are primarily derived from shallow-water mini-basins in the Gulf of Mexico. Subsurface data from the Gulf of Mexico has given insight to a characteristic stratigraphic history to numerous salt withdrawal basins on the continental slope. These GOM-centric models have provided a foundation for successful exploration in the shallow GOM, but the relationships break down in the deeper slope due to an increased influence of local tectonics due to salt movement, and a decreased influence of sediment supply related to sea-level change. The papers below demonstrate the models, as well as some instances where their applications are limited.

Winker (1996) describes in detail the Trinity/Brazos fan system in the Gulf of Mexico that progressively filled- and spilled-through the topography of four intra-slope basins, depositing various seismic facies in each basin. The "fill and spill" model (Booth et al., 2000) suggests a process dominated by sediment-driven-subsidence accommodation tied to eustatic sea-level changes along the margin. In this model, developed principally through work in the Auger and Macaroni basins in the Gulf of Mexico, they define five phases of minibasin development. These include (a) healing phase in intra-slope sinks; (b) ponded phase sheets in distal sinks; (c) bypass of channel and overbanks; (d) gorge system development and bypass to more distal sinks; and e) normal faulting in proximal slope with footwall fills. Similarly, Sinclair and Tomasso (2002) attempted to define a simplistic model for confined turbidite basins by incorporating outcrop data from upper slope Tertiary Alpine basins with subsurface data from the Gulf of Mexico. They conclude that the progressive infill of confined turbidite basins can be characterized by four phases: (a) flow ponding, where incoming flows are totally trapped; (b) flow stripping, where the finer, more dilute portion of the flow is able to escape over the confining topography; (c) flow bypass, either by flows traversing over the filled basin or by switching of feeder channels away from the basin; and (d) Blanketing, of the basin and surrounding topography due to base-level rise.

DeVay et al. (2000) suggest that the process of filling and spilling works best in relatively low sediment input scenarios in which the basin fill rate is equal to or less than the rate of salt displacement, otherwise sediments will be able to reach the abyssal plain with relatively little obstruction. In another scenario, Wood (2006) suggests that the process might vary dramatically in the more distal minibasin systems of the Gulf of Mexico, where basins are farther removed from the influences of eustatically-driven shelf edge sediment supply changes. Montoya and Hudec (2007) and Madof et al., (2009) also acknowledge this dilemma, in that that complex accommodation scenarios in distal slope settings generate more complex accommodation and sedimentation histories, and require more robust models to understand the dynamics and 3D evolution of minibasins.

Badalini, G., B. Kneller, and C. D. Winker, 1999, Late Pleistocene Trinity-Brazos turbidite system; depositional processes and architectures in a ponded mini-basin system, Gulf of Mexico continental slope: AAPG Bulletin, v. 83, p. 1297–1298.

Beaubouef, R. T., and S. J. Friedmann, 2000, High resolution seismic/sequence stratigraphic framework for the evolution of Pleistocene intra slope basins, western Gulf of Mexico; depositional models and reservoir analogs: Program and Abstracts—Society of Economic Paleontologists. Gulf Coast Section. Research Conference, v. 20, p. 40–60.

Booth, J. R., A. E. DuVernay, III, D. S. Pfeiffer, and M. J. Styzen, 2000, Sequence stratigraphic framework, depositional models, and stacking patterns of ponded and slope fan systems in the Auger Basin; central Gulf of Mexico slope: Program and Abstracts—Society of Economic Paleontologists. Gulf Coast Section. Research Conference, v. 20, p. 82–103.

DeVay, J. C., D. Risch, E. D. Scott, and C. Thomas, 2000, A Mississippi-sourced middle Miocene (M4), fine-grained abyssal plain fan complex, northeastern Gulf of Mexico: AAPG Memoir, v. 72, p. 109–118.

Liu, J., Y., and W. R. Bryant, 1999, Seafloor Morphology and Sediment Paths of the Northern Gulf of Mexico Deepwater: Gulf Coast Association of Geological Societies Transactions, v. 49, p. 4.

Madof, A. S., N. Christie-Blick, and M. A. Anders, 2009, Stratigraphic controls on a salt-withdrawal intraslope minibasin, north-central Green Canyon, Gulf of Mexico: Implications for misinterpreting sea level change: AAPG Bulletin, v. 93, p. 535–561.

Mallarino, G., R. T. Beaubouef, A. W. Droxler, V. Abreu, and L. Labeyrie, 2006, Sea level influence on the nature and timing of a minibasin sedimentary fill (northwestern slope of the Gulf of Mexico): AAPG Bulletin, v. 90, p. 1089–1119.

Prather, B. E., 1998, Classification, lithologic calibration, and stratigraphic succession of seismic facies of intraslope basins, deep-water Gulf of Mexico; errata, in J. R. Booth, G. S. Steffens, and P. A. Craig, eds., AAPG Bulletin, United States, American Association of Petroleum Geologists : Tulsa, OK, United States, p. 707R–707R.

Prather, B. E., 1998, A Gulf of Mexico based depositional process model for above-grade slopes: AAPG Bulletin, v. 82, p. 1953-1953.

Sinclair, H. D., and M. Tomasso, 2002, Depositional evolution of confined turbidite basins: Journal of Sedimentary Research, v. 72, p. 451–456.

Winker, C. D., 1996, High-resolution seismic stratiraphy of a late Pleistocene submarine fan ponded by salt-withdrawal minibasins on the Gulf of Mexico continental slope: Proceedings—Offshore Technology Conference, v. 28, Vol. 1, p. 619-628.

Wood, L. J., 2006, Source-to-sink sediment movements in structurally complex setting; the role of gateway basins: Abstracts: Annual Meeting—American Association of Petroleum Geologists, v. 15, p. 115–115.

Physical Models—Influence of Topography in the Deepwater Environment

These papers were selected to understand the dynamics among the mechanics of turbidity currents, deep-water bathymetry, and the resulting deposits that are formed. Implications are also discussed for sediment bypass and delivery to more distal locations on the slope.

Lane-Serff, G. F., L. M. Beal, and T. D. Hadfield, 1995, Gravity current flow over obstacles: J. Fluid Mech., v. 292, p. 39–53.

2-D currents over an obstacle were studied, in which both a passive and active finite upper layer were considered. The theoretical analysis was based on shallow-wave theory and the precictions for the flow proportion that continues over the obstacle, the speed of the reflected jump and the reflected flow depth were compared reasonably well with laboratory experiments. The authors have noted experimental results suggesting that run-out up topography may be up to 4.5 times the height of the flow thickness.

Rottman, J. W., J. E. Simpson, J. C. R. Hunt, and R. E. Britter, 1985, Unsteady gravity current flows over obstacles: Some observations and analysis related to the phase II trials: Journal of Hazardous Materials, v. 11, p. 325–340.

In this paper, a 2-D gravity current meeting an obstacle was investigated. They examined the case where the upper layer of the lighter (ambient) fluid is infinitely deep and hence remains stationary. The authors have noted experimental results suggesting that the body of a flow will surmount topography less than 2.5 times the body thickness.

Kneller, B., and W. McCaffrey, 1999, Depositional effects of flow nonuniformity and stratification within turbidity currents approaching a bounding slope; deflection, reflection, and facies variation: Journal of Sedimentary Research, v. 69, p. 980–991.

This paper is based on the premise that the flow of turbidity currents and pyroclastic flows into regions with topography produces spatial variation in flow. The variation (flow nonuniformity) affects not only the loci of deposition, but also the depositional facies. An example from an Oligocene turbidite system with a bounding slope is used to demonstrate this occurrence. Outcrop constraints were used to develop a simple model of basinal paleotopography, and the nonuniformity of flows resulting from their interactions with it. The observed facies variation corresponds closely with predictions based on this pattern of nonuniformity. They observed that turbidite sandstones thin onto the confining surface and proposed that this was controlled principally by flow magnitude. Thus type of pattern would have been produced by small- magnitude, quasi-steady and/or surge-type turbidity currents that were able to carry their sand load on less steep slopes than those that could be run up by higher-magnitude flows. The authors above have noted experimental results suggesting that the body of a flow will surmount topography less than 1.5 times the head height.

Kneller, B., and C. Buckee, 2000, The structure and fluid mechanics of turbidity currents; a review of some recent studies and their geological implications: Sedimentology, v. 47, p. 62–94.

This paper reviews existing literature on the structure and behavior of sediment gravity currents, with particular attention to turbidity currents. Questions of definition are discussed between dense currents, which may deposit 'en masse,' and more dilute currents, which tend to be more dispersive where sedimentation is concerned. A summary of more recent experimental studies and mathematical models is used to illustrate the physical nature of gravity currents, with emphasis on the velocity and turbulence structure, and the stability of stratification. These components and the mathematical parameters that characterize them are used to determine implications for interpreting flow process from deposit architecture and vice versa.

McCaffrey, W., and B. Kneller, 2001, Process controls on the development of stratigraphic trap potential on the margins of confined turbidite systems and aids to reservoir evaluation: AAPG Bulletin, v. 85, p. 971-988.

The authors describe the types of sediment pinch-out onto confining margins using outcrop studies. They suggest that there is continuum between two types of pinch-out configuration. For Type-A, turbidites thin onto the confining surface (relatively abruptly), and individual beds tend not to erode older deposits. In type B, turbidite sandstones commonly thicken toward the confining slope, and beds may incise into earlier deposits. These two types may occur in combination, to give a wide spectrum of pinch-out characteristics. Their analysis suggests the principal control in determining pinch-out character is flow magnitude, with smaller flows producing type A and larger flows producing type B. Paleoflow indicators and a systematic analysis of vertical successions of beds and their thickness variations are suggested to provide clues to the direction of flow and location of confining topography.

Lamb, M. P., T. Hickson, J. G. Marr, B. Sheets, C. Paola, and G. Parker, 2004, Surging versus continuous turbidity currents; flow dynamics and deposits in an experimental intraslope minibasin: Journal of Sedimentary Research, v. 74, p. 148–155.

This article focuses on the dynamics and deposits of both surging and continuous turbidity currents flowing into a model mini-basin. In the analysis, the authors employed the use of a Ponding Index to quantitatively illustrate the differences between the deposits formed from each type of event. They suggest that the differences between the deposits are likely due to the relative proportion of head to body of the flows, where (1) the continuous flows led to the establishment of a quasi-stead dammed turbidity current, which resulted in uniform deposition with a low Ponding Index, while (2) the surge events were sufficiently small to be contained by the basin, and deposited "ponded" deposits that were characterized by relatively higher Ponding Indices. Further implications for interpreting the ability of a basin to trap sediment from each type of flow are discussed, and the implications for interpreting the deposit geometries of single events versus cumulative events are described.

Lamb, M. P., H. Toniolo, and G. Parker, 2006, Trapping of sustained turbidity currents by intraslope minibasins: Sedimentology, v. 53, p. 147–160.

This paper describes a simple model to predict the trapping of sediment in an experimental basin based on the relative magnitudes of the input discharge of turbid water and the detrainment discharge of water across a settling interface. Their model show a limiting case, whereby a basin captures 100% of the sediment from a ponded turbidity current until sediment deposition raises the settling interface above the downstream lip of the mini-basin. They therefore postulate that the mechanism is similar for mini-basins filling in nature, and that the trap efficiency of sediment can be expected to be high until the mini-basin is substantially filled with sediment.

RPSEA Lobster Project Results

The Research Program to Secure Energy for America (RPSEA) is funded by the U.S. Government in a variety of topics. Under their Deepwater Reservoirs theme the QCL has a joint research effort underway with Dr. Sanjay Srinivasan in the UT Petroleum Engineering Department to utilize the Lobster Field area and data in a study of deepwater reservoir connectivity. The talks, reports and website link below are part of the research transfer products for that project.

Website: Deepwater Systems Library (DSL)

Talks

• Dr. Sanjay Srinivasan: Deepwater Reservoir Connectivity: an Integrated Geologic and Engineering Approach
  • (.ppt)
• Dr. Sanjay Srinivasan: Ultra-deepwater resources to reserves development through improved appraisal
  • (.ppt)

Technology Transfer: Talks

• Dr. Lesli Wood: Statoil Lobe/Channel Transitions Project Review, April 26, 2012
  • (.ppt)
• Vishal Maharaj: Interaction Between Turbidity Currents and Confining Mini-basin Topography: A Review of Existing Models, Experimental Insights and Subsurface Data Applications, Technical Sessions Seminar, September 18, 2012
  • (.pptx)
  • (.ppt)
  • Movie MVI_1995 (.mov)
  • Movie MVI_2077 (.mov)

Technology Transfer: Data Sheets

• These data constitute the length and width of lobes within two separate lobe complexes in the Lobster Field, an upper slope Pliocene-age mini-basin in the north central Gulf of Mexico. In both complexes, lobes shingle to the east in response to an eastward located normal fault, and individual lobes of each complex backstep toward the northern basin margin and become aerially smaller. In each lobe complex, the oldest and stratigraphically deepest lobe is largest.
  • Lobster lobes (.xlsx)
  • Lobster lobes (.xls)