"Interpreting Complex Traps from Seismic Outcrops Lithology, Porosity, and Fluids are Now Possible to Image with Seismic"
Date: Monday, October 7, 2002
Place: Westchase Hilton, 9999 Westheimer
Time: Social 5:30 p.m., Dinner 6:30 p.m.
The present is the key to the past,” was stated by Hutton over a century ago. Today the present is focused on technology, specifically, the improved image capabilities of seismic data. With the recent developments in “Seismic Petrophysics,” it is now possible to image lithology, porosity, and fluids on the seismic data.
The ability to image lithology, porosity, and fluids allows us to attack complex traps from a geological perspective. We can switch gears from amplitudes, impedance, and reflectance to actual geology. That means we are no longer looking at seismic, we are looking at “seismic outcrops.” This allows us to do a more detailed geologic interpretation. Trap settings become much more apparent in the geologic domain than in the seismic domain. Also, the interpreter can concentrate on the specific trapping mechanism, such as facies changes, porosity variation, or an unconformity.
Several examples are reviewed illustrating geological solutions to complex trapping problems. These include porosity variations in a fluvial reservoir, lithologic variations in a nearshore marine sequence, and the identification of a gas-depleted zone.
Biographical Sketch:
Gordon W. VanSwearingen is the Exploration Manager for eSeis Inc. He received a BS in biology and geology from the University of Pittsburgh and later pursued graduate studies in geology at Duke University. He joined eSeis, Inc. in September 2000. Prior to joining eSeis, he worked 2 years for Utah International, 12 years for Amoco Production Company, 2 years for Eastern States Exploration Company, and 7 years for Mortimer Exploration Company.
Mr. VanSwearingen’s geological experience includes coal and uranium exploration as well as hydrocarbon exploration and production. His work for Utah International was surface exploration and assessment of unconventional uranium traps in the Appalachian Basin. While at Amoco he was both a geologist and supervisor in prospect generation, operations and exploitation, and regional/frontier trends. The plays included conventional clastic and carbonate traps as well as coalbed methane and deepwater reservoirs. He was also instrumental in developing several training seminars on deepwater exploration and participated in Amoco’s Deepwater Fan Task Force. As Vice President of Exploration for Eastern States Exploration his responsibilities included the organization, budgeting, and management of exploration and development programs in the Appalachian and Illinois Basins. As Exploration Manager for Mortimer Exploration Company he developed exploration strategies fitted to specific investor requirements, and managed 3D seismic projects from the acquisition through interpretation and drilling. His primary interest has been the interpretation and relationship of depositional facies to reservoir and trap.
"Soil Features Common to the Houston Area, (As Seen by a Soil Scientist)"
Date: Wednesday, October 9, 2002
Place: Rudy Lechners 2503 S. Gessner (1/2 block North of Westheimer)
Time: Social 5:30 p.m., Dinner 6:30 p.m.
Soil science focuses on a very thin layer of the earth’s surface where biologic and physico-chemical processes join to form perhaps the most complex environment on the earth. To many field geologists, this zone that so occupies soil scientists is just a distraction before getting down to the “real” business. Yet the morphology and processes of this thin layer very much control what travels from the surface to deeper layers and what kind of transformations might occur during the trip.
In this presentation, I focus on common features that geologists might encounter during fieldwork in the Quaternary formations on the Upper Gulf Coast of Texas. We will examine features associated with our expansive soils, including gilgai and slickensides. We will also examine accumulations that occur in the soil, such as redoximorphic concentrations of iron (aka “mottles”), calcium carbonate or caliche, gypsum, and manganese. We will discuss what these pedogenic (soil-formed) concentrations tell us about the environment of their formation.
Biographical Sketch:
John S. Jacob holds a joint appointment with the Texas A&M Sea Grant Program and the Texas Agricultural Extension Service (Department of Soil and Crop Sciences). He has coast-wide responsibility for inland environmental problems that have a direct impact on the quality of our bays, estuaries, and coastal waters. Pre-eminent among these issues are the mitigation and abatement of runoff pollution from both rural and urban sources and the preservation and restoration of valuable natural habitats such as wetlands.
Dr. Jacob is trained as a soil scientist with a BS and a MS in soil sciences from Texas Tech University, and a PhD from Texas A&M University. He worked several years for the National Cooperative Soil Survey program in Texas, mainly in the coastal plain area. Dr. Jacob has been actively involved in the evolution of soil and site evaluation for on-site septic systems for several years. He teaches several short courses around the state on soil and site evaluation.
He is co-author of the Texas Coastal Wetlands Guidebook. He is recognized as a Professional Wetland Scientist by the Society of Wetland Scientists and a Certified Soil Scientist by the American Society of Agronomy.
" Geology And Exploration Potential Of The Veracruz Basin "
Date: Monday, October 21, 2002
Place: Westchase Hilton, 9999 Westheimer
Time: Social 5:30 p.m., Dinner 6:30 p.m.
Abstract:
While the Veracruz region of southeastern coastal Mexico has produced oil and gas for 50 years, a joint Pemex-Schlumberger integrated evaluation shows that the Veracruz basin’s exploration potential remains very significant.
The basin has had a complex Mesozoic-Cenozoic evolution. Early Mesozoic rifting divided the Mexican margin into a series of basement blocks separated by thinned continental crust. During post-rift subsidence, Jurassic and Cretaceous platformal carbonates were deposited on the basement blocks, while basinal carbonates accumulated above areas of thinned crust. In the Late Cretaceous-Early Eocene an east-verging thrust belt developed along the eastern margin of Mexico. This deformation produced an emergent imbricate thrust fan composed of largely Cretaceous strata that forms the western margin of the Veracruz basin. The basin thus developed in the unusual setting of a “foreland basin” located along a rifted, subsiding continental margin. A rift-related basement fault block, the Teziutlan Massif, forms the northern boundary of the basin; the San Andres Tuxtla volcanic center forms a southern boundary.
From the Early Eocene to the present the emergent thrust belt has provided sediment to the Veracruz basin via high-gradient streams. As a consequence of this topography, the depositional setting along the western margin of the basin abruptly changes from one of incised fluvial systems to deep marine environments. As a result of differential subsidence and sedimentation, the thrust front was buried and more than 8 kilometers of Cenozoic sediments accumulated in the basin to the east. Benthic foraminiferal data indicate that most of the sediments were deposited in a bathyal environment (water depth between 200 to1000 meters) that progressively shallowed through the Cenozoic. Eustatic sea level changes are superimposed upon this general pattern.
In the central part of the basin, Neogene strata show two major depositional cycles. From the late Early Miocene to earliest Late Miocene there is an upward progression from submarine fan deposits to submarine channel and overbank deposits to an eastward prograding deltaic assemblage. A second, earliest Late Miocene--Early Pliocene depositional cycle is characterized by a progression from a submarine channel facies to an eastward prograding shelf-delta facies.
In the Middle and early Late Miocene, a series of fault-propagation anticlines developed across the onshore and near offshore part of the basin as a result of compression probably related to a period of rapid subduction of the Cocos plate beneath the Pacific margin. Offshore, beyond the zone of compressional structures, detached extensional deformation occurred during the Plio-Pleistocene.
More than 400 MMBO and about a TCF of gas have been produced from fracture-enhanced Cretaceous carbonates in 16 fields of the buried frontal thrust zone. In the Veracruz basin proper, five gas fields have been discovered in latest Middle Miocene to lower Pliocene submarine channel-levee deposits and amalgamated deepwater sand sheets that are draped over or wrapped around the Miocene anticlines. Recent 3-D seismic surveys have been effective at delineating this play. The Cocuite Field provides a well-documented example of an accumulation in a channel-levee system.
Gas from these latter fields is a mixture of both thermogenic and biogenic gas. Jurassic source rocks underlying the basin are likely over-mature, making Cretaceous oil-prone source rocks and Paleogene gas-prone sediments the most likely sources of thermogenic gas in Tertiary strata. Faults are probable pathways for dominantly vertical migration of thermogenic gas. Biogenic gas was generated in Neogene depo-centers and dominantly migrated laterally toward structural highs.
Currently, the Cocuite-type play is being actively explored and developed. Additionally, in the western part of the basin potential plays include up-dip pinchouts of Paleocene sands beneath unconformities, incised valley fill, shallow marine deltaic deposits, and fractured Cretaceous carbonates thrust over Paleogene clastic strata. In the central part of the basin additional potential exists for channelized reservoirs in older Neogene and Paleogene deposits. Based on facies patterns, submarine fan deposits are inferred to be present east of the central part of the basin.
Biographical Sketch:
Robert G. Hickman received his B.S. degree in geology from Stanford University and Ph.D. in geology from the University of Wisconsin-Madison. He spent much of his career with Unocal Corporation working as a structural geologist and as coordinator of structural geology/remote sensing. He has expertise in thrust belts, regions of extensional and salt tectonics, and geographic experience in Cordilleran basins, sub-Andean basins, Southeast, South and Central Asia, the Middle East, and the Gulf of Mexico. He is a member of AAPG, GSA, AGU, and HGS and is a certified petroleum geologist (CPG # 5694). Doing business as Structural Solutions, Bob specializes in analysis of complex structures, regional tectonic studies, and fractured reservoir analysis, and presents structural courses. He can be reached at: rhickman@pdq.net
"The relationship of depositional and diagenetic history to reservoir distribution and quality in the Muspac and
Catedral Fields, Reforma Area, Chiapas, Mexico “
Gas and condensate are produced from Middle and Upper Cretaceous carbonates in complex faulted domal traps. The Middle Cretaceous is characterized by stacked shallowing upward cycles (< 20m thick), grading upward from tight subtidal mudstones at the base to porous packstones/grainstones that constitute the reservoir. Porosity is interparticle and intraparticle with minor vugs and fractures. The depositional environment was shallow subtidal platform, with local buildups of tidal flat islands.
The Upper Cretaceous is characterized by thick (>50m) coarsening upward cycles, capped by massive porous (>15%) rudist skeletal grainstone/packstone units that are the dominant reservoir. Fracturing contributes to the high flow capacity and excellent interconnection of reservoir layers. The fracture porosity is small in comparison to the high interparticle porosity, however, so that fractures are only a minor part of the reservoir storage.
The Muspac-Catedral area resides near the southern edge of an extensive carbonate shelf. The Middle Cretaceous represents simple aggradation on a subsiding shallow platform. The Upper Cretaceous is characterized by major flooding events followed by rapid progradation of the thick grainstone/packstone units. This depositional model contrasts with the slope breccia model, which has been applied to reservoir sections elsewhere in the Reforma Area. Locally extensive subaerial exposure, related to sea level low-stands, has resulted in the formation of karstic solution collapse breccias in low energy intertidal facies and the development of moldic and secondary interparticle porosity in higher energy grainstones and packstones. Karstic breccias have low matrix porosity (i.e. storage capacity), but typically retain fracture porosity (high flow capacity).
R. Michael Lloyd , Roxana Oil
“Exploration Significance of Petroleum Systems Evaluation in the Veracruz Basin, Mexico”
Oil and gas source and maturity, oil-source correlation, source-rock maturity distribution, hydrocarbon generation modeling, and petroleum system evaluation have outlined the oil and gas potential of the Veracruz Basin and the hydrocarbon types to be found in different areas. Hydrocarbon generation/migration is active over the entire basin. Three petroleum systems contributed to hydrocarbon accumulations. The Mesozoic Petroleum System (MPS), containing Tithonian and Cretaceous source rocks, contributed to oil and thermogenic gas accumulations. The Paleogene Petroleum System (PPS), containing Paleocene, Eocene, and Oligocene sources, contributed to thermogenic gas accumulations. The Neogene Petroleum System (NPS), containing immature Miocene and Pliocene sources, contributed to biogenic gas accumulations.
Timing of oil and gas migration and trap formation, migration pathways, and petroleum system evaluation suggest oil and thermogenic gas from MPS can be found in the Buried Tectonic Front (BTF) and Homoclinal Trend (HT), and only gas from MPS can be found in the Loma Bonita Trend (LBT) and Tlalixcoyan Syncline (TS). Gas from MPS is expected in most of the Coatzacoalcos Reentrant (CR). Minor mature oil from MPS can also occur in southeastern CR. PPS contributed mainly thermogenic gas in LBT, TS, and CR. NPS contributed biogenic gas over the entire basin. Gases from different sources are often mixed in reservoirs.
Estimated thermogenic gas charges show that only a fraction of the available gas from MPS has been discovered in Neogene plays. The Veracruz Basin east of BTF has excellent potential for large to small gas discoveries. Future exploration should focus on progressively deeper plays.
Suhas Talukdar, consultant, and Edgar Guevara, BEG, Austin.
Place: Albuquerque, New Mexico.
" Sequence and Seismic Stratigraphy of the Bossier Formation (Tithonian), Western East Texas Basin "
Date: Monday, October 28, 2002
Place: Westchase Hilton, 9999 Westheimer
Time: Social 5:30 p.m., Dinner 6:30 p.m.
Abstract:
Sequence and seismic stratigraphic analysis of well logs and 2-D seismic lines from Freestone, Leon, Houston, Madison, Robertson and Limestone Counties, TX., demonstrates that the Bossier Formation of the Western East Texas basin can be subdivided into two recognizable sequences separated by a major sequence boundary (SB-2). Similarly, the Bossier Formation is also bracketed by a basal (SB-1) and upper (SB-3) sequence boundary separating it from the Cotton Valley Lime below, and the Cotton Valley Sand above, respectively.
In seismic sections, the SB-2 boundary in the middle of the Bossier Formation was identified by tracing mounded basal reflectors, and sigmoid signatures representing basin floor and slope fans. This boundary was correlated onto the shelf below stacked deltas. In well log sections, basin floor fan log signatures can be traced laterally into slope fan and stacked delta log facies. These basin floor and slope fans represent a lowstand systems tract, whereas the Lower Bossier represents a transgressive systems tract and the upper Bossier represents a prograding complex.
Burial history analysis suggests that the Lower Bossier accumulated during a time of rapid mechanical subsidence when the East Texas basin was underfilled. A drop in sea level associated with the SB-2 boundary represents a major climate shift from tropical to cooler conditions favoring rapid influx of sands from the ancestral Mississippi, Ouachita and Red River Systems. These sands developed inner shelf prograding deltaic packages, outer shelf and incised valley fill stacked deltas, and basin submarine fan systems. The stacked deltas and basin fan sand systems all represent prospective gas plays.
Biographical Sketch:
George D Klein’s expertise is in Clastic Facies and Reservoirs (Deepwater, Deltas, Fluvial), Clastic Reservoir Characterization, Sequence Stratigraphy, Seismic Sedimentology, Basin Analysis and Framework Geology. Basins with which he has expertise include the Gulf Coast, East Texas, Illinois, Appalachian, Arkoma, Powder River, Los Angeles, Reconcavo, Maracaibo, Eastern Venezuela, Marib, Orange River, Eastern Carpathian, Veracruz, Cook Inlet, and Fundy basins. He published 287 refereed articles, books and abstracts on these topics, including the book "Sandstone Depositional Models for Exploration for Fossil Fuels" (1985) and a widely-used Wall Chart on "Vertical Sequences and Log Shapes of Major Sandstone Reservoir Systems" (1984).
Klein discovered the largest gas producing well in the Barber County field, WV, a new exploration play concept in the eastern Gulf Coast, a delta-front trough play concept in the Reconcavo basin, Brazil, a deep water channel fairway system and sheet sand play in the Veracruz basin, Mexico, and a slope fan/basin floor fan play in the East Texas basin. He has also completed recent core description assignments for PDVSA/Omni Laboratories in Venezuela, Halliburton/PDVSA in Venezuela, the eastern Mediterranean offshore, the Orange River basin offshore South Africa, and the Eastern Gulf of Mexico, onshore.
Klein’s clients include AKG Oil CO., Austin, TX; BPZ & Associates, Houston, TX; Brooklyn Union Gas Co., Inc; Forest Oil International; G.A.S. Unlimited, Inc., Stafford, TX; GENMIN, Johannesburg, South Africa; Halliburton Energy Co.; Illinois Basin Petroleum Co., Florissant, MO; Illinois Energy Associates, Champaign, IL; Longleaf Energy Group Inc., Brewton, AL; NUMATEX, Inc, St. Louis, MO; Omni Laboratories; PDVSA; PEMEX E & P; Perez Companc; PETROBRAS; Phillips Petroleum Co., Inc, Bellaire, TX; R & C Energy, New York, NY; Schlumberger, Inc.; Samedan International, Inc., Houston, TX, Seagull Energy E & P; SEECO, Fayetteville, AR; SEIS-STRAT Services Inc., Houston, TX; Texaco, Inc., and Unocal.
Klein received ten honors and awards including the Outstanding Paper Award in the Journal of Sedimentary Petrology (SEPM; 1972) a Senior Research Fellowship from the Japan Society for the Promotion of Sciences, a Senior Fulbright Research Fellowship in the Netherlands, and the Laurence L. Sloss Award of the Geological Society of America.
Klein earned degrees in geology from Wesleyan University (BA), Kansas (MS) and Yale (PhD.). He worked as a Research Geologist for Sinclair Research and then taught at the Universities of Pittsburgh, and Pennsylvania. He joined the University of Illinois in Urbana-Champaign in 1970 where he was a Full Professor from 1972 until 1993. After serving as Executive Director of the New Jersey Marine Sciences Consortium, and Director, New Jersey Sea Grant College Program, he opened a full time geological consulting practice (SED-STRAT Geoscience Consultants, Inc.) in the petroleum field in May 1996. He is a member of AAPG (DPA Certified Petroleum Geologist #5662), SEG, SIPES (CPES #2705), AIPG (Certified Professional Geologist #1487), HGS, SEPM, and GSA.
14019 SW Frwy, Suite 301-#335, Sugar Land, TX, 77478-3563 TEL: 281-937-9436; FAX: 281-937-9456; e-mail: gdkgeo@concentric.net
"Maverick Misterios-Comanche Ranch Field, Maverick County, Texas "
Date: Wednesday, October 30, 2002
Place: Petroleum Club, 800 Bell Avenue, Downtown
Time: Social 11:15 a.m., Lunch 11:45 a.m.
The initial well in the Comanche Ranch field was drilled to a total depth of 6,730 ft on April 2002 and reached the basal Glen Rose of the Cretaceous. The prospect was originally intended to be a Glen Rose reef play based on 3-D seismic acquired in 2001.
Since the discovery oil well was so prolific, Saxet Petroleum Inc. has kept two rigs drilling continuously and has drilled over 10 successful wells.
The reservoir is not a reef but is composed of carbonate rocks deposited as a reworked forereef facies. These rocks have undergone episodic tectonism including joint fracturing and thrusting, as well as alteration via hot hydrodynamic flow of deep-seated acidic fluids. These fluid incursions have metamorphosed localized areas, creating secondary porosity and permeability that now define the trapping mechanism. There is also evidence of secondary hydrocarbon migration.
Many of the initial wells have been conventionally cored and this information is still being analyzed.
This paper is a very preliminary report and a synthesis of Saxet Petroleum’s activities to date. There remain many unanswered questions about Comanche Ranch Field. What are the defining reservoir parameters, the ultimate reserve potential, the proper well stimulation and completion procedures, the reservoir diagenetic history, the geologic history, and perhaps most importantly, what is the significance of the field to future exploration efforts in the region?
Biographical Sketch:
Brian E. O’Brien is the co-founder and owner of Saxet Petroleum Inc. of Houston, Texas. He received a BS in geology in 1957 and an MS in geology in 1963 from the University of Oklahoma. Mr. O’Brien began his career as a mudlogger, followed thereafter as a geologist and geophysicist with ARCO. In 1969, O’Brien was employed by Mesa Petroleum, Inc. and was responsible for Texas Gulf Coast and Offshore Louisiana, working out of Houston. During this time, Brian came up with a Wilcox (later to be named Lobo) play south of the city of Laredo. Mesa’s management turned down this concept, and it was at that time he decided to pursue his ideas on his own. In 1972, O’Brien, in conjunction with A. R. Sanchez, Sr., John R. Blocker, A. R. Sanchez, Jr., and Joe Thomas, formed South Texas Exploration Company, which was the forerunner of Sanchez-O’Brien Oil and Gas Company (“SOBOG”) with offices in Houston and Laredo.
Brian E. O’Brien can boast of one of the best exploration track records in the oil and gas industry. As president and co-founder of SOBOG, from the time period beginning in 1974 and ending in 1997, SOBOG, operated and drilled 696 wells and completed 325 gas wells and 102 oil wells. This represents a success rate of 61%. The results of these efforts were the discovery of more than 1 TCF of gas and 17 MMB of oil. These reserves were almost entirely found in South Texas, which also happens to be Saxet’s primary focus area.
Mr. O’Brien is an ardent supporter of the University of Oklahoma, having served on numerous advisory boards and committees. He is currently a member of the Alumni Advisory Board for the College of Geosciences and the University of Oklahoma Foundation, Executive Committee.
Depositional Processes and Characteristics of Siltstones, Mudstones and Shales
Date: Wednesday October 30, 2002
Time: 8:00 am - 4:30 pm
Place: 2002 GCAGS Annual Meeting
Registration: GCAGS Web site
Siltstones, mudstones and shales have been studied with regard to clay mineralogy and general transport-deposition. Recent studies on deep water deposits from cores and outcrops have shown that fluid flow properties of deep water reservoirs are greatly affected by the presence of finer-grained deposits in the reservoir. Initial analysis indicates that the majority of these finer-grained deposits are siltstones rather than the previously supposed mudstones, commonly called shales. Studies on these deposits have indicated that they are comprised of fine silt laminae sandwiched between films of clay minerals, quartz dust and organics. To date, little attention has been given to their characteristics resulting from different depositional processes. Internal characteristics, based on the different types of transport, and the resulting structures after compaction and diagenesis are poorly understood. Depending on the transport-deposition process, the architecture of the deposit will have different 3D extents and continuity. Stratigraphic prediction of the position and dimensions of the finer-grained beds can indicate whether the deposits will be a barrier or a baffle to fluid flow. Minor variations in depositional style and other characteristics can result in more differences than presently assumed.
Program - Twelve speakers will conduct four sessions of talks with discussion time after each session. A general discussion time will be held at the end. Lunch and snacks will be provided.