ALBERT

Description: In the northeastern Gulf of Mexico, Upper Jurassic Smackover inner ramp, shallow-water thrombolite buildups developed on paleotopographic features in the eastern part of the Mississippi Interior Salt basin and in the Manila and Conecuh subbasins. These thrombolites attained a thickness of 58 m (190 ft) and were present in an area of as much as 6.2 km2 (2.4 mi2). Although these buildups have been exploration targets for some 30 yr, new field discoveries continue to be made in this region. Thrombolites were best developed on a hard substrate during a rise in sea level under initial zero to low background sedimentation rates in low-energy and eurytopic paleoenvironments. Extensive microbial growth occurred in response to available accommodation space. The demise of the thrombolites corresponded to changes in the paleoenvironmental conditions associated with an overall regression of the sea. The keys to drilling successful wildcat wells in the thrombolite reservoir play are to (1) use three-dimensional seismic reflection technology to find paleohighs and to determine whether potential thrombolite reservoir facies occur on the crest and/or flanks of these features and are above the oil-water contact; (2) use the characteristics of thrombolite bioherms and reefs as observed in outcrop to develop a three-dimensional geologic model to reconstruct the growth of thrombolite buildups on paleohighs for improved targeting of the preferred dendroidal and chaotic thrombolite reservoir facies; and (3) use the evaporative pumping mechanism instead of the seepage reflux or mixing zone models as a means for assessing potential dolomitization of the thrombolite boundstone. Ernest A. Mancini is regional director of the Eastern Gulf Region of the Petroleum Technology Council, director of the Center for Sedimentary Basin Studies, and professor in petroleum geology in the Department of Geological Sciences at the University of Alabama. His research focus is on reservoir charactertization and modeling, petroleum systems, and the application of stratigraphic analysis to petroleum exploration.Juan Carlos Llinás obtained his B.A degree from the National University of Colombia in 1995 and his M.S. degree in 2003 from the University of Alabama, and he is currently working on his Ph.D. at the University of Alabama. He is studying Smackover oil fields associated with microbial reef buildups and genetically related depositional facies using well and seismic data. William Parcell is an assistant professor in the Department of Geology at Wichita State University. His research integrates sequence stratigraphy, microbial sedimentology, and soft-computing techniques in stratigraphic modeling. He received his B.S. degree (1994) from the University of the South (Sewanee, Tennessee), his M.S. degree (1997) from the University of Delaware, and his Ph.D. from the University of Alabama (2000). Marc Aurell received his B.A. degree (1985) and his Ph.D. (1990) in geology from Zaragoza University. He is currently working at Zaragoza University as a professor. Most of his work in the last 20 years has been concentrated on facies and sequence-stratigraphic analysis of the Mesozoic and Cenozoic carbonate platforms developed in the Iberian basin and in the Pyrenees (Spain). Beatriz Bádenas obtained her B.A. degree (1991) and her Ph.D. (1999) in geology at Zaragoza University, where she teaches courses in stratigraphy and sedimentology. Her major research interests include facies and sequential analysis of carbonate sediments in shallow platform settings. She is currently studying the application of high-resolution sequence stratigraphy and cyclostratigraphy to Upper Jurassic carbonate platform strata of the Iberian basin. Reinhold Leinfelder, paleontologist, carbonate sedimentologist, and basin analyst, specializes in Jurassic reef systems. He received his Diploma degree from the University of Munich in 1980 and his Ph.D. in 1985 and a postdoctoral habil degree in 1989 from the University of Mainz. He was an associate professor at the University of Stuttgart (1989–1998), and he is now a full professor at the University of Munich. Joe Benson is a professor in the Department of Geological Sciences and senior associate dean of the College of Arts and Sciences at the University of Alabama. His research interests lie in carbonate sedimentology and sedimentary petrology. He received a B.A. degree from the College of Wooster and an M.S. degree and a Ph.D. from the University of Cincinnati.

Description: Reservoir characterization, modeling, and simulation were undertaken to improve production from Womack Hill field (eastern Gulf Coast, United States). This field produces oil from Upper Jurassic Smackover carbonate shoal reservoirs. These reservoirs occur in vertically stacked, heterogeneous depositional and porosity cycles. The cycles consist of lime mudstone and wackestone at the base and ooid grainstone at the top. Porosity has been enhanced through dissolution and dolomitization. Porosity is chiefly interparticle, solution-enlarged interparticle, grain moldic, intercrystalline dolomite, and vuggy pores. Dolostone pore systems and flow units have the highest reservoir potential. Petroleum-trapping mechanisms include a fault trap (footwall uplift with closure to the south against a major west-southeast–trending normal fault) in the western area, a footwall uplift trap associated with a possible southwest-northeast–trending normal fault in the south-central area, and a salt-cored anticline with four-way dip closure in the eastern area. Potential barriers to flow are present as a result of petrophysical differences among and within the cycles, as well as the presence of normal faulting. Reservoir performance analysis and simulation indicate that the unitized western area has less than 1 MMSTB of oil remaining to be recovered, and that the eastern area has 2–3 MMSTB of oil to be recovered. A field-scale reservoir management strategy that includes the drilling of infill wells in the eastern area of the field and perforating existing wells in stratigraphically higher porosity zones in the unitized western area is recommended for sustaining production from the Womack Hill field. Ernest A. Mancini is regional director of the Eastern Gulf Region of the Petroleum Technology Council, director of the Center for Sedimentary Basin Studies, and professor in petroleum geology in the Department of Geological Sciences at the University of Alabama. His research focus is on reservoir characterization and modeling, petroleum systems, and the application of stratigraphic analysis to petroleum exploration.Tom Blasingame is an associate professor in the Department of Petroleum Engineering at Texas A&M University. He holds B.S. and M.S. degrees and a Ph.D. from Texas A&M University in petroleum engineering. He is a distinguished member of the Society of Petroleum Engineers and a member of the Society for Exploration Geophysicists and AAPG. Rosalind Archer holds a Ph.D. in petroleum engineering from Stanford University. Her research interests are in reservoir characterization, well testing, and reservoir simulation. She is currently a lecturer in the Department of Engineering Science at the University of Auckland, Auckland, New Zealand. She is also an adjunct assistant professor in the Department of Petroleum Engineering at Texas A&M University. Brian Panetta is a research associate in the Department of Geological Sciences at the University of Alabama. He received a B.S. degree from the University of South Carolina, an M.S. degree from the University of Kentucky, and an M.S. degree and a Ph.D. from the University of Alabama. His research interests are in reservoir characterization and geologic modeling. Juan Carlos Llinás obtained his B.A degree from the National University of Colombia in 1995 and his M.S. degree in 2003 from the University of Alabama, and he is currently working on his Ph.D. at the University of Alabama. He works in geologic modeling of oil fields with siliciclastic and carbonate reservoirs using well-log, core, and seismic data. Charles D. Haynes is a businessman and educator with degrees in mining and petroleum engineering. He was an independent petroleum producer before joining the faculty at the University of Alabama. He continues his professional practice through minerals-related research, consulting, and joint ownership of an independent oil-producing company. He serves on the State Board of Licensure for Engineers and Land Surveyors. Joe Benson is a professor in the Department of Geological Sciences and senior associate dean of the College of Arts and Sciences at the University of Alabama. His research interests lie in carbonate sedimentology and sedimentary petrology. He received a B.A. degree from the College of Wooster and an M.S. degree and a Ph.D. from the University of Cincinnati.

Description: Appleton oil field, located in Escambia County, Alabama, was discovered in 1983 through the use of two-dimensional seismic reflection data. The field structure is a northwest-southeast-trending paleotopographic ridge comprised of local paleohighs. The field produces from microbial reef boundstones and shoal grainstones and packstones of the Upper Jurassic Smackover Formation. Because Appleton field is approaching abandonment, owing to reduced profitability, an integrated geoscientific study of the field structure and reservoir was undertaken to determine whether drilling additional wells in the field would extend the productive life of the reservoir. The conclusion from the integrated study, which included advanced carbonate reservoir characterization, three-dimensional geologic visualization modeling, seismic forward modeling, porosity distribution analysis, and field production analysis, was that a sidetrack well drilled on the western paleohigh should result in improved oil recovery from the field. The sidetrack well was drilled and penetrated porous Smackover reservoir near the crest of the western paleohigh. The well tested 136 bbl oil/day. Ernest A. Mancini is professor of geology in the Department of Geological Sciences at the University of Alabama, where he also serves as director of the Center for Sedimentary Basin Studies, an interdisciplinary petroleum research center, and as director of the Eastern Gulf Region of the Petroleum Technology Transfer Council, the primary technology transfer organization for the petroleum industry in the region. He is a former state geologist and oil and gas supervisor for the state of Alabama.Joe Benson received his B.A. degree from the College of Wooster and his M.S. degree and Ph.D. from the University of Cincinnati. From 1973 until 1978 he was a geologist with the Lake Erie Section of the Ohio Geological Survey. In 1978 he joined the Department of Geology at the University of Alabama, where he is presently professor of geology and associate dean for science and mathematics in the College of Arts and Sciences. His research focuses on the depositional and diagenetic history of carbonates with emphasis on controls on reservoir evolution and quality. Bruce Hart was a petroleum geologist at the New Mexico Bureau of Mines and Mineral Resources when this work was conducted. He is currently assistant professor with the Department of Earth and Planetary Sciences at McGill University. He has taught short courses on three-dimensional seismic interpretation for SEPM, GSA, PTTC, and other organizations. His research focuses on integrating three-dimensional seismic methods with other approaches to understand subsurface physical properties and to address fundamental problems in stratigraphy and structural geology. Robert Balch is a research associate in the Reservoir Evaluation and Advanced Computational Technologies Group of the Petroleum Recovery Research Center at the New Mexico Institute of Mining and Technology. His current research interests are primarily in the field of reservoir characterization using artificial intelligence tools such as fuzzy logic and neural networks. He has a B.S. degree from Evergreen State College and an M.S. degree and Ph.D. in geophysics from New Mexico Tech. William Parcell is currently a doctoral candidate at the University of Alabama. His primary research interests are carbonate sequence stratigraphy and stratigraphic modeling. He received his B.S. degree (1994) from the University of the South, Sewanee, Tennessee, and his M.S. degree (1997) from the University of Delaware. He has worked on facies analysis of Middle Jurassic carbonates in Montana and Wyoming and controls on the distribution of Upper Jurassic reefs in the United States Gulf Coast, France, and Portugal. Brian Panetta received a B.S. degree (1992) in geology from the University of South Carolina and a M.S. degree (1995) in geology from the University of Kentucky. Since 1997 he has worked as a staff geologist for the Center for Sedimentary Basin Studies at the University of Alabama, where he is also pursuing his Ph.D. His research is focused on three-dimensional modeling of petroleum reservoirs.