"Opportunity in a World-class Hydrocarbon Basin: Trinidad and Tobago’s Eastern Offshore Marine Province"by Lesli J. Wood (1) and Carolyn Roberts (2)(1)Bureau of Economic Geology, University of Texas at Austin, Austin, Texas lesli.wood@beg.utexas.edu (2)Ministry of Energy and Energy Industries, Trinidad & Tobago, Port-of-Spain, Trinidad croberts@energy.gov.tt |
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The eastern offshore marine province (EOM) of the eastern East Venezuela Basin is one of the most prolific hydrocarbon provinces in the world with proven reserves of over 486 MMbl and 23.4 TCF of natural gas (Fig. 1). Combined proven, probable and possible reserves in the offshore basin are calculated at over 1.5 billion bbl of oil and 33.5 TCF of gas. Development of liquified natural gas (LNG) processing facilities on the island of Trinidad over the past 5 years has turned the small island nation into a leading world supplier of LNG. Trinidad currently exports to Spain, as well as providing over 40% of the LNG needs of the United State’s east coast customers (Barrionuevo, 2001). Some estimate exploration potential to total 50-70 TCF of gas in a country where companies experience an 80% success rate of wells (Thomas, 2001). Rising U.S. gas prices in early 2001 have many U.S. industries considering relocating or expanding to Trinidad. The combination of a stable government, synchronous design of hydrocarbon markets, and new exploration and development opportunities has forced companies to take notice of the region’s potential alongside that of west Africa, eastern South America and the U.S. Gulf of Mexico (Thomas, 2001). An ongoing cycle of bid rounds (1996, 1998 and 2001 [closing on September 4, 2001]) in both onshore and offshore acreages will open up new development opportunity in existing fields and exploration opportunity in the unexplored deep and ultradeep water acreage.
The Graveyard of Geologists
The majority of current offshore production occurs in the region defined by Leonard (1983) as the Columbus Basin. Almost 100% of the current wells are drilled in water depths of less than 150 meters and are located less than 100 kilometers from onshore processing facilities. Often referred to as the “graveyard of geologists” the basin is developed along the oblique transpressional margin of the Caribbean and South American plates. The basin is bounded on the south by the stable Orinoco Offshore Platform and on the north by the thrust-cored Darien Ridge (Fig. 1). It is the eastern extent of a transpressional deformation front that has advanced diachronously toward the southeast in direct response to the eastward migration of the Caribbean plate (Erikson and Pindell, 1993; Lugo and Mann, 1995; Parnaud and others, 1995).
The most recent oblique foreland basin, the Columbus Basin is filled with over 12 kilometers of clastic, late Tertiary age sediments (Wood, 2000). The Orinoco River has been the primary source of sediment for the basin, having established an outlet to the Atlantic sometime during the early Miocene (Diaz de Gamero, 1995). The Orinoco River and Delta advanced onto the eastern shelf during the high-frequency shoreline changes of the Pliocene and Pleistocene. Its supply-dominated nature meant that periods of rising shoreline had little effect on its progradational character. The Cretaceous age passive margin, which dips steadily to the north from the Venezuelan margin, formed a stable platform across which pre-Pliocene distal marine shales were deposited (DiCroce, Vail and Bally, 1999). Rapid deposition of Pliocene and Pleistocene clastics that followed resulted in significant mobilization of underlying under-compacted shales. Compressional plate boundary stresses combined with depositional loading to produce a significant number of mud volcanoes throughout the late Tertiary. This diapiric activity continues today on the present-day seafloor and in subaerial portions of the modern delta (Huyghe and others, 2000; Brami and others, 2000; Aslan and others, 1998). The combination of active tectonics, strong oceanographic processes, late Tertiary sea level changes and enormous sediment supplies makes for a complex hydrocarbon systems that justifies its label as the graveyard of geologists.
Integration for Answers
Exploration and production activity has increased in the basin throughout the past decade, spurred by competition between companies anxious to grow their involvement in the region’s hydrocarbon industry. This growth has been driven by the need to prove reserves in anticipation of LNG development and maintain the domestic energy supply, including that vital to downstream methanol and ammonia industries. These activities resulted in the publication of several papers regarding the sequence stratigraphy of the basin (Wood, 2000; Pocknall and others, 1999; Pocknall and others, 1998), application of new seismic technology (Sharp and others, 1998; Day and others, 2000), and hydrocarbon maturation and migration (Heppard and others, 1998). The majority of present-day public knowledge is confined to the offshore extensional province; however, recent drilling and data acquisition in deepwater acreage has begun to increase understanding of the more distal provinces of the eastern offshore marine area (Fig. 2 ; Patterson and others, in press; Brami and others, 2000). Although varyingly complex in their structure and stratigraphy, these distal provinces are referred to here as the minibasin and the compressional tectonomorphic provinces for simplicity.
Primary structural elements in the extensional province of the basin include: 1) a series of transpressional northeast-southwest trending ridges and 2) northwest-southeast oriented, down-to-the-northeast normal faults. Major hydrocarbon fields trend along the basin’s four principle ridges. They are defined as the Samaan-Galeota Ridge, Poui-Teak-Omega, Ibis-Pelican-Oilbird and Cassia-East Mayaro anticlinal trends (Fig. 2). Normal faults are generally younger to the northeast as are the hydrocarbon traps and reservoir ages. Hydrocarbons are trapped in a series of downthrown four-way, bow-tie anticlinal structures with east-west closure formed by two-way subsidence-driven rollover, and north-south closure formed by uplift along the thrust-cored ridges (Fig. 3).
Fauna and flora extinctions and evolutions, as well as some abundance data, derived from over 41 wells were combined with abundant seismic data, outcrop, and log facies analysis by Wood (2000) and Pocknall and others (1998 and 1999) to establish a chronostratigraphic framework for the extensional province of the EOM. Ten progradational clastic wedges form the Pliocene-Pleistocene stratigraphic architecture of the area (Fig. 4) . These wedges prograded from southwest to northeast and are youngest to the east. They were sourced primarily by the wave-dominated paleo-Orinoco delta and can show a great degree of lateral continuity in facies along depositional strike. Within each wedge, the depositional facies deepen progressively from southwest to northeast, changing from (1) terrigenous fluvial/estuarine to (2) progradational or aggradational shoreface to (3) middle and outer neritic shelf to (4) slope and finally to (5) basinal facies over distances of a few kilometers. The distal toes of these sequences downlap onto distal submarine shale ridges. Depositional sequences average 10,000 to 12,000 ft in thickness and accumulated over relatively short periods of time (300 to 500 kYr). These sequences are considered third and fourth-order based on the definition of Mitchum and Van Wagoner (1991). The sequences are bounded at their bases by sequence boundaries of basinwide extent that include, from oldest to youngest, (1) NBP (3.8 Ma), (2) GLS (3.6 Ma), (3) B8LS (3.0 Ma), (4) BB2LS (2.3 Ma), (5) NLS (2.0 Ma), JLS (1.78 Ma), HLS (1.5 Ma), ELS (1.0 Ma), DLS (0.8 Ma) and BLS (0.5 Ma) (Fig. 4).
Bow-tie Anticlines
The pre-Pliocene mobile shales exert a significant influence on the geometry and kinetics of hydrocarbon traps forming in association with prograding megasequences. Megasequences are cut by a series of down-to-the-northeast growth faults that appear to sole out above the underlying Mesozoic strata (Fig. 3 ; i.e., roll-over faults of Rowan and others, 2000). Regional extension initiates normal faulting and diapiric rise (Jackson and others, 1994). Sediment accumulation in the developing accommodation space exacerbates shale evacuation beneath the prograding wedge. Shales evacuate to the east along the gently dipping Mesozoic detachment surface to form toe-of-slope diapirs. Sediments thicken to the west in response to accommodation developing in the hanging wall of the normal roller faults, and they thicken to the east in reponse to accommodation developing along counter-regional glide plane surfaces associated with the evacuated shale diapirs. Once the mobile substrate is exhausted and a shale weld occurs, the supply-dominated deltaic depositional systems fill any remaining accommodation space. The entire system then steps basinward to the next developing normal fault and the process begins again. The result of these series of events is bi-directional off-crest stratigraphic thickening and bi-directional rollover resulting in the formation of a bow-tie shaped anticline (Figs. 3 and 5 ). The entire system resembles the classic Gulf of Mexico-style Roho fault systems classified by Rowan and others (2000) as a Roller Fault Family. Significant rollover fault development can be seen in these extensional province, bow-tie anticlinal structures with younger rollover fault segments migrating basinward and upward. Such basinward migration of roller faults is in response to basinward migration of the anticlinal hinge over time caused by seaward evacuation of shale in the distal shale roller (M. Jackson, pers. comm.). When employing a fill-and-spill model of hydrocarbon charge (Gibson and Bentham, 2000), the occurrence of such rollover faulting has implications for the secondary migration and distribution pattern of hydrocarbons throughout these bow-tie anticlinal structures.
Although exploration in the extensional province of the EOM has been ongoing for nearly half a century, significant discoveries continue to be made by companies active in the area. Recent successes by EOG Resources with its Osprey-1 and Tanager-1 wells and BP discoveries at Red Mango (Farmer, in press) and Manakin-1 make current blocks open for bid in the present bidround more prospective. Major technical issues in the extensional province continue to be seal presence and in deeper facies, reservoir sand volumes, as well as drilling problems (i.e., high pore pressure) associated with deeper stratigraphic horizons.
Opportunity in New Provinces
Significant industry and government focus in the past several years has been placed on deep water opportunities in the EOM area of Trinidad. Exploration activity by most companies throughout the late 1990s has been focused on the minibasin tectonomorphic region (Patterson and others, in press; Brami and others, 2000; Ramkhelawan and others, 2000) with an eye toward future seismic acquisition and drilling opportunities in the ultra-deep, compressional province (Fig. 1).
The minibasin province occurs basinward of the present-day shelf-slope break and extends ~120 km northeastward. At least three major shoreline lowstands (1.0, 0.8, and 0.5 m.y., Fig. 4) have transferred sediments out to and beyond this province. Mud diapirs and toe thrusts bound basins that can be asymmetric to either the basin or the shelf (Fig. 6) . Escape sedimentation dominates this province occuring in and around these bathymetric highs (Fig. 7) . Hydrocarbons may migrate along the shale diapir/flank faults or within the overpressured and fractured diapir itself to charge these basins at depth, then continue migration updip until limited by petrophysical or lithologic pinchout. It was generally accepted by most geoscientists that diapirs post-date thrust faulting, with faults acting as fluid conduits to the surface and encouraging diapiric rise. However, recent physical modeling of diapiric processes suggest that diapiric rise, driven by regional extension, may predate thrusts, and can provide weaknesses across which thrusts detach when acted on by compressional plate forces (J. De Chalvez, pers.comm.,).
Principle technical issues in the monoclinal province appear from early drilling results to be hydrocarbon presence and migration (Ramkhelawan and others, 2000). Yeilding and Apps (1994) documented that in the Gulf of Mexico, it was approximately 113 km from the blocky, lobate sand bodies of the lower slope to the coeval updip shelf margin. In the EOM area of Trinidad, transport of the late Pleistocene (1.0, 0.8 and 0.5 m.y. lowstands) coeval shelf margins 100 kilometers east, would place well-developed lower slope reservoirs significantly farther east than the current exploration blocks. Companies currently exploring in the paleoslope bypass province recognize the need to move basinward to find quality reservoir sands.
The compressional province occurs approximately basinward of the 1600-m bathymetric contour and extends to the front of the modern accretionary prism (Fig. 1). Older, pre-Pliocene section shallows stratigraphically eastward, away from the axis and depocenter of the EOM basin (Sanchez, in press; Cresini, 1998). Therefore, this province may offer significant opportunity for exploration success in older strata and traps. Here, sediment sinks form in piggyback basins between thrusts associated with accretionary wedge subduction. Depocenter axes in asymmetric-to-the-basin piggybacks migrate toward the shelf as progressive thrusting backrotates the older host sheet (Fig. 8). Upper Pleistocene, deep-marine, basin floor turbidites most likely exhibiting sheet geometries (similar to their modern counterparts; Faugeres and others, 1993; Huyghe and others, 2000) show mounded and shingled offlap seismic facies. They are perched along the rising eastward basin margins and intermingle with large slumped debris flow deposits. Hydrocarbons can migrate into these basins along deep, bounding thrusts and associated faults. In the backrotated basin, hydrocarbons may migrate updip into traps formed in perched, basin floor turbidite deposits or be found in later thrust-fault traps associated with progressive subduction of the wedge (Fig. 9) .
The principle technical concerns in this province is most likely hydrocarbon migration and presence. Reservoirs are deposited as debris flows around and off the flanks of growing structures. There is some uncertainty about sand content in these deposits. However, the strong deep currents, well documented off this continental margin, probably rework deposits and may result in clean, concentrated and well-sorted reservoirs in certain deep-water locations. The active tectonic nature of this province creates concerns of trap integrity, but opportunities exist to produce late structural traps as younger thrusts cross-cut older debris flows. Proximity to the continental/oceanic crust boundary creates hydrocarbon source and generation concerns that will be resolved only through well tests.
Summary
The EOM area of Trinidad and Tobago is a world-class gas and oil province with profitable markets and prolific reserves. Although current proven, probable and possible reserves in the entire country currently are 1.5 billion bbl of oil and over 33 TCF of gas, much of the available acreage has yet to be explored. Current and developing markets both on the island and in the United States make this a very attractive E & P region, combined with a stable government and good infrastructure.
The eastern marine basin is located near the juncture of the Atlantic, Caribbean and South American plates and its character and fill are strongly influenced by the oblique collision between the Caribbean and South American plates, as well as compressional tectonics from the Caribbean plates overriding the more eastward Atlantic plate. The basin can be divided into at least three major tectonogeomorphic provinces: extensional, monoclinal minibasin and compressional, each with its own unique processes for generation of accomodation space and basin filling.
Within the extensional province, extension, compression and sediment loading combine to produce a regional normal, roller fault system that are younger to the east, and abundant shale diapirs with associated counter-regional glide planes. Ten large mega-sequences of Pliocene-Pleistocene age form the basin’s fill with fluvial facies transitioning westward to deep marine fans and slope deposits. These wedges thicken across normal faults and down into basinward counter-regional surfaces to form bow-tie anticlines with crests that migrate basinward as one moves stratigraphically higher in the section. Secondary rollover faults, developing in response to this crestal migration influence, charge pathways and segregate hydrocarbons across the larger anticlinal structures.
The minibasin province, currently the focus of exploration activity in the area is dominated by abundant shale diapir growth around which interbasin fill-and-spill processes occur. Several significant deep-marine, slope leveed-channel features are identifiable on seismic from the area. This province serves as a sand conduit to deeper marine regions. Significant remaining technical issues in this province are hydrocarbon migration and source rock maturation.
The compressional province, located distal of the 1600-m bathymetric contour to the front of the present day accretionary prism, is a region of piggyback basin formation with depocenters that translate basinward or landward in response to loading by proximal thrust sheets. Documented strong oceanographic processes offer the opportunity to rework debris flow deposits into quality reservoirs. However, active tectonics increase the risk of seal breach and loss of hydrocarbons into younger, shallow sediments.
Figure 1 . Techno-geographic map showing regional structural features, northern South America, including the island of Trinidad and Tobago, and the extensional, minibasin and compressional provinces associated with Trinidad's eastern offshore marine (EOM) hydrocarbon basin.
Figure 2 . Major structural features of the EOM area including regional roller faults, right lateral strike slip faults and offshore anticlinal ridges. Major hydrocarbon fields are distributed along these ridges.
Figure 3 .NE-SW trending seismic line X-X' and line drawing modified from Wood (2000) showing down-to-the-northeast roller faults (D, G, H and H1), remnant shale buldges and characteristic bow-tie anticlines that are younger to the northeast. Note the abundance of roller faulting that climbes upsection to the northeast indicating growth and basinward miration of anticline crests.
Figure 4 . Chronostratigraphic chart of the Trinidad eastern offshore marine province (Colombus Basin of Loenard, 1982). Note the overall continuous progradational character of megasequences in the basin.
Figure 5 . Schematic illustration of a bow-tie anticlical structure developing in the hanging wall of a roller fault. Sediments thicken in the landward directions along normal growth faults and in the basinward direction along counter-regional faults associated with large toe-of-slope shale diapirs. Significant secondary rollover faults forming from structural crest migration basinward will have a significant impact on hydrocarbon distribution as fluids fill-and-spill their way across the structure.
Figure 6 . Seismic and line drawing from the minibasin province in Trinidad’s EOM area showing the seismic facies and structure across the area.
Figure 7 Schematic figure of the interbasin, escape sedimentation processes active across the minibasin tectonomorphic province.
Figure 8 Seismic line showing piggyback basin from the compressional basin associated with tha Barbados Accretionary Prism illustrating the migrating depocenters characteristic of the piggyback basin type shown
Figure 9 Schematic figure of the compressional piggyback basin province of the Trinidad eastern offshore marine area.
References:
Aslan, A., Morton, R.A., White, W.A., Raney, J.A. and Guevara, E.H., 1999, Geologic Framework of the Holocene Orinoco Delta, Venezuela: American Association of Petroleum Geologists 1999 annual meeting, Annual Meeting Expanded, p. A7-A8, 1999, San Antonio, TX, United States.
Barrionuevo, A., 2001, How Trinidad became a major U.S. supplier of liquefied natural gas: in The Wall Street Journal, Tuesday, March 13, 2001, p. A1 and A8.
Brami, T., Pirmez, C., Archie, C., Heeralai, S., and Holman, K., 2000, Late Pleistocene deep-water stratigraphy and depositional processes, offshore Trinidad and Tobago: Paper presented at GCSSEPM 20th Annual Conference held in Houston, Texas, U.S.A., December 3-6, 2000 (article and color illustrations available on CD-ROM made available to meeting participants and the public titled Deep Water Reservoirs of the World, P. Weimer, R.M. Slatt, J. Coleman, N.C. Rosen, H. Nelson, A.H. Bouma, M.J. Styzen and D.T. Lawrence (eds.).
Cresini, C., 1998, Sequence Stratigraphy and Thermal Maturation of the Pomeroon Concession, Offshore Guyana: unpublished Master's Thesis, University of South Carolina, Columbia South Carolina, U.S.A.
Day, R., Burch, T., Lehmann, C., and Hoffman, K., 2000, Data integration for velocity modeling and depth conversion, Trinidad and Tobago: in 32nd Annual Offshore Technology Conference 2000 Proceedings, Vol. 1:Geology, earth sciences and environmental factors, p. 41-43.
Diaz de Gamero, M. I., 1996, The changing course of the Orinoco River during the Neogene: a review: Palaeogeography, Palaeoclimatology, and Palaeoecology, v. 123, no. 1-4, p. 385-402.
Di Croce, J., Bally, A., and Vail, P., 1999, Sequence stratigraphy of the Eastern Venezuelan Basin: in Mann, P., editor (series editor: K.J. Hsu) Caribbean Basins, Sedimentary Basins of the World, v., 4, Elsevier Science B.V., Amsterdam, p. 417-474.
Pindell, J. L., and J. P. Erikson, 1993, Mesozoic passive margin of northern South America, in J. A. Salfity, ed., Cretaceous tectonics in the Andes: Wiesbaden, FRG, Vieweg Publishing, Earth Evolution Sciences, International Monograph Series, p. 1-60.
Farmer, C., Shaw, E.R. and Burch, T.K., in press, The Red Mango Area - discovery and delineation of a 3 TCF gas field, Columbus Basin, offshore Trinidad (abs.): AAPG Annual Meeting 2001, Program with Abstracts, Denver, Colorado, U.S.A.
Faugeres, J-C., Gonthier, E., Griboulard, R., and Masse, L., 1993, Quaternary sandy deposits and canyons on the Venezuelan margin and south Barbados accretionary prism: Marine Geology, v. 110, Elsevier Science Publishers, B.V., Amsterdam, p. 115-142.
Gibson, R.G., and Bentham, P.A., 2000, Use of fault-seal analysis in understanding petroleum migration in a complexly faulted anticlinal trap, Columbus basin, offshore Trinidad: Port-of-Spain, Trinidad, GSTT/SPE Annual Meeting Abstracts with Program, p. 87.
Heppard, P. D., H. S. Cander, and E. B. Eggertson, 1998, Abnormal pressure and the occurrence of hydrocarbons in offshore eastern Trinidad, West Indies, in B. E. Law, G. F. Ulmishek, and V. I. Slavin, eds., Abnormal pressures in hydrocarbon environments: AAPG Memoir 70, p. 215-246.
Huyghe, P., Nugnier, J-L., Griboulard, R., Deniaud, U., Gonthier, E., and Faugeres, J-C., 1999, Review of tectonic controls and sedimentary patterns in Late Neogene piggyback basins on the Barbados Ridge Complex: in Mann, P., editor (series editor: K.J. Hsu) Caribbean Basins, Sedimentary Basins of the World, v., 4, Elsevier Science B.V., Amsterdam, p. 369-388.
Jackson, M.A., Vendeville, B.C. and Schultz-Ela, D.D., 1994, Structural Dynamics of Salt Systems: Annual Earth Review and Planetary Science, v. 22, p. 93-117.
Leonard, R., 1982, Geology and hydrocarbon accumulations, Columbus Basin, offshore Trinidad: AAPG Bulletin, v. 67, p. 1081-1093.
Lugo, J. and Mann, P., 1995, Jurassic-Eocene tectonic evolution of Maracaibo Basin, Venezuela: in Tankard et al., (eds.) Petroleum Basins of South America: American Association of Petroleum Geologists Memoir, 62, pp. 699-725.
Mitchum, R. M. and Van Wagoner, J. C., 1991, High frequency sequences and eustatic cycle in the Gulf of Mexico Basin: in J.M. Armentrout and B.F. Perkins (eds.), Sequence Stratigraphy as anExploration Tool - Concepts and Practices in the Gulf Coast: Gulf Coast Section, Society of Economic Paleontologists and Mineralogists Foundation, Program and Abstracts, Eleventh Annual Research Conference, Houston, Texas, pp. 257- 267.
Patterson, M.B., Blom, F., Griffith, C.M., Tepper, B.J. and Truempy, D., in press, Sweet music in the Columbus Basin: From Mozart to Haydn, and Then? (abs.): AAPG Annual Meeting 2001, Program with Abstracts, Denver, Colorado, U.S.A.
Parnaud, F. Y., Y. Gou, J-C. Pascual, I. Truskowski, O. Gallango, H. Passalacqua, and F. Roure, 1995, Petroleum geology of the central part of the Eastern Venezuela basin, in A. J. Tankard, R. Sua'rez, and H. J. Welsnik, eds., Petroleum basins of South America: AAPG Memoir 62, p. 741-756.
Pocknall, D. T., L. J. Wood, and A. F. Geen, 1999, Depositional facies in the Pliocene-Pleistocene section, offshore eastern Trinidad: Port-of-Spain, Transactions of the 14th Caribbean Geologic Conference, unpaginated.
Pocknall, D. T., L. J. Wood, A. F. Geen, B. E. Harry, and R. W. Hedlund, 1996, Integrated paleontological studies of Pliocene to Pleistocene deposits of the Orinoco Delta, eastern Venezuela and Trinidad (abs.): Houston, 9th International Palynological Congress, Program and Abstracts, Texas, unpaginated.
Ramkhelawan, R. Bhajan, J., Rampersad, T.R., Shepard, D.B., Weir, G.M. and Wharton, S.R., 2000, Seismic attribute analysis of deepwater reservoirs, offshore east coast Trinidad (abs.): Paper presented at the Geological Society of Trinidad and Tobago SPE conference held in Port-of-Spain, Trinidad and Tobago, July 10 - 13, (article and color illustrations available on CD-ROM made available to meeting participants and the public at www.gstt.org).
Rowan, M. G., Jackson, M. P., and Trudgil, B. D., 1999, Salt-related fault families and fault welds in the northern Gulf of Mexico: American Association of Petroleum Geologists Bulletin, vol. 83, no. 9, p. 1454-1484.
Sanchez, Marel, 2001, Sequence stratigraphy and structural framework of Southeast Caribbean Margin: Orinoco Delta offshore, Venezuela. Unpublished master's thesis, University of Texas at Austin, p.
Sharp, J., Pish, T. and Bailey, J., 1998, Integration of 3D seismic technologies to predict Pliocene gas sands; post appraisal of the El Diablo-1 discovery, Trinidad: AAPG conference and exhibition Abstracts, AAPG Bulleting, v. 82, no. 1, p. 1966.
Thomas, K., 2001, Trinidad and Tobago Gas Reserves Drawing U.S. Interest, Oil and Gas Journal Online.
Yeilding, C. and Apps, G., 1994, Spatial and temporal variations in the facies associations of depositional sequences on the slope: examples from the Miocene-Pleistocene of the Gulf of Mexico: in Submarine Fans and Turbidite Systems:Sequence stratigraphy, reservoir architecture and production characteristics: Gulf of Mexico and International: P. Weimer, A. H. Bouma and B.F. Perkins (eds.). GCSSEPM Foundation 15th Annual Research Conference, p. 423-437.
Wood, L.J., 2000, Chronostratigraphy and tectonostratigraphy of the Columbus Basin, eastern offshore Trinidad: American Association of Geologists Bulletin, vol. 84, no. 12, p. 1905-1928.
