ALBERT

Description: Deformation-band networks at Buckskin Gulch, Utah, and the Big Hole fault, Utah, both formed in the Navajo Sandstone with similar initial porosity and permeability, at similar burial depths, and result in similar reductions in effective permeability. However, the band networks at Buckskin Gulch, which formed in a contractional tectonic setting, appear to be much more areally extensive and are not associated with any discrete faults having displacements greater than at most a few meters and more likely only a few tens of centimeters. In contrast, the bands at Big Hole fault are generally limited to the damage zone of a about 25-m (82-ft) displacement normal fault formed in a locally extensional environment. These results suggest that deformation bands in well core from extensional settings may be indicative of discrete damage zones associated with normal faults, whereas deformation bands in well core from contractional settings may be indicative of much more areally extensive deformation-band networks. The band networks in both cases will affect similar reductions in reservoir effective permeability, but only in the latter case will the affected area be sufficiently large to affect well performance. John Solum is a structural geologist with the Clastics Reservoir Research Team at Shell International Exploration and Production. He received his B.S. degree in geology from Utah State University (1998) and his M.S. degree (2001) and Ph.D. (2005) from the University of Michigan. Prior to joining Shell in 2007, he was on the faculty at Sam Houston State University in Huntsville, Texas (2006–2007), and a Mendenhall Fellow at the U.S. Geological Survey in Menlo Park, California (2005–2007). J. P. Brandenburg received his B.S. degree in geology from Michigan State University in 2000 and his Ph.D. in geology from the University of Michigan in 2008. He is currently employed as a research geologist by Shell Upstream Projects and Technology in Houston, Texas. He specializes in numerical modeling techniques for geology. Stephen Naruk has more than 20 years of experience with Shell, in multiple exploration and production and research and development assignments. He is currently a principal structural geologist and leads both Shell's Clastics Reservoir Research Team and the Structural Geology Center of Expertise within Shell's Expertise and Deployment organization. Olga V. Kostenko is a production geologist with the Perdido deep-water venture. She is involved in drilling operations, reservoir modeling, and structural evaluation of near-field exploration opportunities. She received her geological engineering degree from Kyiv State University, Ukraine, and her Ph.D. in geology from the University of Oslo, Norway (2002). Prior to joining Shell, she was a project geoscientist for exploration and research projects in Canada, Ukraine, Russia, and Kazakhstan while working for small independent oil and gas companies. Her previous assignment with Shell (2005–2008) was with the Novel Appraisal Technology Team in Shell International Exploration and Production. She held the position of structural geologist and was involved in research projects and global technical consulting to asset teams mainly in the fields of structural modeling and trap analysis. Scott Wilkins is a structural geologist within the Geoscience Technology group at Anadarko Petroleum Corporation. His current work involves global technical support for exploration and production, focusing on fault seal analysis, fracture characterization, rock mechanics, and seismic interpretation. He was previously in a similar role, as well as New Ventures Exploration, at Shell International E&P (2002–2008). He received his M.S. degree from Florida International University in 1999 and Ph.D. from the University of Nevada, Reno, in 2002. Richard Schultz received his B.A. degree in geology from Rutgers University (1979), his M.S. degree in geology from Arizona State University (1982), and his Ph.D. in geomechanics and structural geology from Purdue University (1987). Since joining the University of Nevada, Reno, in 1990 he has worked in rock fracture and rock mass mechanics, growth and scaling of fractures and deformation bands, and development of deformation-band damage zones and compaction bands.

Description: Industry discoveries to date in the deep-water toe-thrust play have limited column heights and lack any unequivocal thrust-fault-dependent hydrocarbon columns. The causes of the limited success are controversial, the main issue being whether the encountered columns are caused by leaking thrust faults or other causes. The controversy is in large part caused by the presence of no-seismic-image zones that, even on three-dimensional (3-D) prestack-migrated data, obscure the possible thrust cutoffs. We use dipmeter, seismic, stratigraphic, and fluid pressure data to construct an integrated geometrically and kinematically balanced cross section through a recent toe-thrust discovery in which a prominent no-seismic-image zone on the southwest flank of the Alpha structure appeared to be a thrust fault zone holding about 100 m (328 ft) of thrust-fault-dependent oil column. To constrain the structure within the unimaged forelimb, dip panels and fold axial surfaces were constructed from dipmeter data recorded in both a vertical hole and a sidetrack well through the no-seismic-image zone. Stratigraphic tops from both wells were projected through the no-seismic-image zone using the dip panels and axial surfaces, maintaining the observed stratigraphic thicknesses. These data and analyses tightly constrain potential fault locations and offsets within the no-data zone. The resulting structural model shows that the no-seismic-image zone in the forelimb is not a thrust but instead an overturned limb without any fault offset of the pay section. The results show that the trapped hydrocarbons are confined completely within the four-way dip closure, and that the trap's potential is not limited by the thrust faults' seal capacities. In addition, top-seal analyses show that top-seal integrity is not a limiting factor for hydrocarbon column heights at the present time and has not been a limiting factor throughout the geological history of the structure. Taken together, these observations indicate that the column heights are most likely controlled by access to charge instead of trap integrity, consistent with an observed lack of thermogenic hydrocarbons in nearby four-way dip closures. These conclusions imply that where sufficient access to thermogenic charge is present, there may be additional thrust-fault-dependent hydrocarbon columns. Olga V. Kostenko is a structural geologist with the Novel Appraisal Technology Team at Shell International Exploration and Production, Houston, Texas. She received her engineer-geologist degree from Kyiv State University, Ukraine, and her Ph.D. in geology from the University of Oslo, Norway (2003). Prior to joining Shell, she was involved in exploration and research projects in Canada, Ukraine, Russia, and Kazakhstan while working for small independent oil and gas companies. Her work at Shell involves research projects and global technical consulting to asset teams mainly in the fields of structural modeling and trap analysis. Steve J. Naruk joined Shell's Alaska Exploration Division in 1987 after earning a B.S. degree in geology and geophysics from Yale University and an M.S. degree and Ph.D. in geology from the University of Arizona. He subsequently has had exploration assignments in the U.S. mid-continent, west Texas, Nevada, the Appalachians, the Austin Chalk play, southern Alaska, Colombia, Bolivia, and Argentina interspersed with two research and development assignments. He is currently a principal structural geologist for Shell International Exploration and Production where he serves as the team leader for the Fault Characterization and Reservoir Engineering Team. Willem Hack studied geophysics at the University of Utrecht (Netherlands). After a few years with the Institut Français du Pétrol (IFP), he joined Shell in 1991 in Rijswijk where he worked on the development of velocity interpretation tools. Exploration assignments in Hannover (Germany) and Petroleum Development Oman followed. In 2005, he moved to Houston where he is presently working as an explorationist for deep-water Nigeria. Manuel Poupon holds a Ph. D. in geology from the University of Paris, France. He started his career at Compagnie Géneacute;rale de Géophysique (CGG), France in 1991 where he was involved in a variety of exploration and evaluation projects in the North Sea, Persian Gulf, Siberia, and North and South America. He subsequently became the director of technology at Flagship Geosciences-Houston (a CGG spin-off), managing the technical staff in the United States and Mexico. Following Flagship's acquisition in 2000, he headed the Reservoir Services group in Paradigm Houston. He joined Shell in 2002 where he is currently working as a subsurface coordinator for the Exploration in Nigeria (XiN) team in Houston, specializing in seismic facies analysis and 3-D volume interpretation techniques. Hans-Jurg Meyer joined Shell in 1984 with an M.S. degree from the Technical University of Zurich (ETH) (Eidgenössische Technische Hochshule Zürich), Switzerland. He had assignments in Libya, Gabon, United Kingdom, Pakistan, and Egypt. In 2002, he joined Exploration and Production Technology Solutions (EPT-S) in Houston, where he held several positions for Global Exploration in Nigeria (XiN) during the last few years. In 2008, Hans-Jurg joined the Global Appraisal Portfolio, where he is currently working as the Global Appraisal Deepwater Theme Manager. Miguel Mora-Glukstad studied, explored, and drilled in deformed belts for more than 20 years. His main interests are in gaining an understanding of trapping mechanisms and their relationship to oil and gas productivity. He was educated in Latin America (Ecuador, Escuela Politécnica Nacional (EPN), engineering geology, 1985) and Europe (Oxford, United Kingdom, DPhil, structural geology, 1993). He has worked for several oil companies (e.g., Maxus, Occidental) and joined Shell in March of 2006. Charles Anowai has an M.S. degree in geology from the University of Ibadan, Nigeria (1989), and worked as a materials engineer for the Nigerian Federal Ministry for 3 years. Since joining Shell in 1993, he has held jobs in sedimentology, basin modeling, and structural geology in Shell Nigeria and Shell International Exploration and Production. Margaret Mordi is a representative of the Dajo Oil Limited Company.