Topic:
The Future of Four-D
Speaker:
Roger Anderson of Lamont-Doherty Earth Observatory, Columbia University, New York.
Abstract:
Getting more oil out of old fields is the payout of 4-D seismic reservoir
monitoring. 4-D combines the analysis of seismic acoustic changes occurring
over time with other borehole and surface measurements. 4-D analysis has the
ability to track time-dependent changes such as pressure changes and production
histories. The result is a coupled model of oil and gas drainage and a more
accurate simulation of future production.
Evaluating the Subsurface over Time Using Time-Lapse Seismic
The tools and techniques required to interpret past acoustic changes that
have occurred in oil and gas fields perform two essential tasks: 1)
normalization of the seismic images between snapshots taken at different times,
using different equipment and different geometries of acquisition and then
processed differently at the computer center, and 2) interpretation of the
similarities and differences in the acoustic signature of oil, gas, and water
in the reservoir as they change over time.
More than twenty oil and gas fields from (fig. 1, 2) the Gulf of Mexico and the North Sea are the proving ground for new 4-D technology developments. These fields provide contrasts in acoustic response and seismic signal-to-noise, often between reservoirs within the same field, that point to important lessons for the planning of future 4-D reservoir monitoring projects. Conclusions to date are 1) pressure history often affects seismic responses as significantly as oil/gas/water mix changes and 2) volumetric "region-growing" is a method to scan multiple 3-D data sets for changes at a fast enough computational rate to satisfy engineers in charge of production. Region-growing is a signal analysis technique developed for the detection of differences in MRIs, CAT and PET scans, and in anti-submarine warfare. Region-growing is also very useful for the isolation of 4-D seismic differences that are meaningful in reservoirs.
Better understanding of the pattern of drainage to the surface will allow for better planning and execution of recovery programs in the future. Four-D provides the "killer app" for impedance inversions, which are the most likely seismic attributes that can detect change over time in reservoirs. As we get better at 4-D monitoring, more original oil-in-place will be extracted from producing reservoirs.
The 4-D Seismic Reservoir Simulation Loop Seismic inversions will be routinely used on time-lapse seismic data sets to produce impedance differences. These become geostatistical reservoir characterizations and reservoir simulator data to quantify the variations in fluid saturations with time. New 3-D finite element models will be developed to compute synthetic seismic responses to differences detected by the real observations. Seismic-to-petrophysical iterations are added to the simulation loop. The continual updating of the loop forms a planning tool for predicting new drilling targets for recovery of bypassed oil and gas. Repeated looping of information leads to planning the time, spacing, types of receivers and borehole arrays that will be needed to successfully monitor the oil and gas fields of the future.
Biographical Sketch:
Roger N. Anderson is director of Petroleum Technology Research at the
Lamont-Doherty Earth Observatory of Columbia University in New York, where
he has been for the last 24 years. He has a Ph.D in Earth Sciences from the
Scripps Institution of Oceanography, University of California, San Diego. He
spent the last 8 summers with oil and service companies in Houston, most
recently at Western Geophysical. He is the author of more than 150
peer-reviewed scientific and technical papers. He has written a marine
geology textbook and holds 7 U.S. patents. Anderson is on the board of
directors of Bell Geospace, Inc. and 4-D Systems, LLC. His address is
Lamont-Doherty Earth Observatory, Columbia University, Torrey Cliffs Road
and Rt 9W, Palisades, New York 10964, Email:
Roger Anderson
Special Joint Meeting:
Houston Geological Society, Geophysical Society
of Houston, Society of Independent Professional Earth Scientists, Houston Area
Petroleum Landmen, Society of Petroleum Engineers, and Society of Professional
Well Log Analysts
Speaker:
Jack W. Schanck, president of "Spirit Energy 76", a business unit of Unocal.
Abstract:
Jack Schanck, president of "Spirit Energy 76", has been in the forefront of
the dramatic organizational changes at Unocal and will speak to us on his
experiences and their implications for our industry. "Spirit Energy 76" was
formed to maximize Unocal's U.S. operations. Unocal has had recent exploration
success in deepwater areas off Indonesia, according to The Oil Daily, and now
has interest in 153 deepwater blocks in the Gulf of Mexico.
Biographical Sketch:
Jack Schanck began his career at Unocal in 1976 as a geologist in the Gulf
region. A graduate of Allegheny College, he earned first a B.S. in geology
and then obtained an M.S. in geology at Memphis State. He has worked in Unocal's
Houston and Lafayette offices. Schanck was president of Unocal Canada from 1989-91;
vice president of worldwide exploration from 1992-94; group vice president of
oil & gas operations between 1994-96, and was named president of Spirit Energy
76 in the fall of 1996. He is a member of AAPG, SPWLA, and CAPG.
Special Invitation from HGS President Jeffrey Lund on the Importance of the November Luncheon Meeting:
Our society traditionally holds a number of functions jointly with sister professional societies. Dinners with the Geophysical Society of Houston and the Houston Association of Professional Landman are long traditions. Schanck's talk will be a joint meeting of the Houston Geological Society, Geophysical Society of Houston, Society of Independent Professional Earth Scientists, Houston Area Petroleum Landmen, Society of Petroleum Engineers and Society of Professional Well Log Analysts. Because of all the societies involved we are expecting a major turnout, so we encourage early reservations for the November Luncheon meeting through the HGS office.
The November Luncheon with Mr. Schanck is the work of the "Inter-disciplinary Coordinating Council" created in August, 1996, to foster communications among professional groups in the oil and gas industry. HGS Treasurer, Deborah Sacrey is a founding member of ICC. The professional societies represented in ICC serve more than 15,000 combined members. Houston Area Petroleum Landmen (HAPL) current president, Mike Englert and second vice president, Mike Hinze, deserve kudos for making this event happen and for arranging an exciting speaker. This concept has proved to be very popular with the presidents of each society and our luncheon on November 12 at the Petroleum Club will initiate a new tradition encouraging interdisciplinary networking and fellowship!
Reservations:
No reservations. The room only holds 100, and we are expecting a good amount
of student attendance from both Rice and UH. Those interested should get there
early. Park in visitor parking and take the shuttle (Free!) around the campus
to Duncan Hall.
Topic "Ecology of Contaminated Groundwater" (Henry Darcy Distinguished Lecture)
Speaker Philip Bennett, University of Texas at Austin
Preview of Talk Understanding biodegradation of contamination in ground water and soils is vital to staying current in today's environmental geology and engineering workplace. Dr. Philip Bennett of the Univ. of Texas at Austin Department of Geosciences introduces the fundamentals of microbial degradation of hydrocarbons in this lecture, but then delves deep into the geochemical changes in the aquifer and explores the implications of microbial activity upon the weathering of silicates. The presentation will feature excellent visual presentations and some humorous learning devices. A real site where a crude oil pipeline ruptured spilling thousands of gallons of crude oil into the environment, will be analyzed.
Dr. Philip Bennett is a top-notch scientist receiving rave reviews on his outstanding presentation. You are invited to attend The Henry Darcy Distinguished Lecture which is fully funded by the National Ground Water Association and Association of Ground Water Scientists and Engineers (NGWA/AGWSE) to foster interest in ground water at the academic level. This free lecture also sponsored by the Rice University's Energy & Environmental Systems Institute (EESI) and the Houston Geological Society's Environmental & Engineering Geologists Committee.
Abstract When an organic substance, either natural or anthropogenic, infiltrates into an aquifer it becomes a component of a dynamic bio-geochemical system. From the perspective of the subsurface microbe, these compounds may be benign, toxic, or a rich source of carbon in an otherwise carbon-poor environment. Microbes consume this carbon, producing energy, cell mass, and geochemically reactive byproducts. The transformation of organic toxicants by native microorganisms, sometimes known as intrinsic bioremediation, is considered one of the most promising remediation approaches for contaminated ground water. From a geologic perspective, however, rapid metabolic transformation of organic substances also results in dramatic changes in the geochemical ecology of that aquifer, changing the native microbial consortia, aquifer mineralogy and permeability, vadose-zone gas composition, and water chemistry.
This lecture will examine the geology and geochemistry of microbial transformation of hydrocarbons using laboratory experiments, geochemical modeling, and field observations of contaminated aquifers, including results from the collaborative U.S. Geological Survey's Bemidji research program. Hydrocarbon degradation produces bicarbonate, acidity, and organic waste products, potentially changing the bulk geochemistry of the aquifer over wide areas, or more subtly, producing reactive micro-environments near attached microbes. How does oil degrade in ground water, what are the degradation byproducts, and what is the nature of the micro-environment created around an attached microbe? Are these biogeochemical reactions a significant contribution to subsurface mineral diagenesis? Is mineral weathering enhanced only by surface colonizing microbes, or do microbes affect equilibria by altering "bulk" pore-water chemistry? Do microbes colonize mineral surfaces in order to leach necessary nutrients, or is colonization controlled by surface charge and surface roughness? The goal of this lecture is to examine the geochemical consequences of subsurface microbial processes.
Biographical Sketch Dr. Philip C. Bennett is an associate professor in the Department of Geological Sciences at the University of Texas at Austin. He received a B.S. from Evergreen State College; an M.S. in environmental science from the State University of New York College of Environmental Science and Forestry, and a Ph.D in geology from Syracuse University. Since 1984 Dr. Bennett has been working at the U.S. Geological Survey's Bemidji research site as part of the multidisciplinary "Toxic Substances Hydrology Program." His research projects at the University of Texas include silicate weathering kinetics, vadose zone gas transport and chemistry, geochemical fate of high explosives, sediment transport in karst aquifers, reactive solute transport in fractures, and computational quantum-chemical descriptions of silicate surfaces.
Topic Elk Hills
Speakers Jonathan G. Kuespert and Jeevan P. Anand, EGOR, Los Angeles, CA
Abstract In late 1995 President Clinton authorized the sale of the Federal Government's controlling interest in the billion barrel Elk Hills Naval Petroleum Reserve (NPR#1), located near Tupman, California. The two year sale process, including independent reserve evaluation, sales presentations, equity redetermination, and bid evaluation, has drawn to a close. Bids that initiate the next phase of the process were due on October 1, 1997.
Elk Hills: Sale of the Century
The Elk Hills sale is occurring at a time of significant change within the
California oil and gas production community. In the Gulf Coast the focus of
the major oil companies has been a shift in operations from the onshore and
inner continental shelf to the deeper waters of the Gulf Coast. In California
the opposite trend has dominated. The recent merger of CalResources (the
former Shell-Western) with Mobil-California into AERA, the recent Texaco
purchase of the largest independent in California (Monterey Resources), the
continued consolidation of producing assets, the increased production and
refining of heavy oil, the large consumer demand for clean-burning natural gas,
the shift of Alaskan light crude off the West Coast market, the future addition
of a new multi-crude pipeline from the San Joaquin Valley to Los Angeles area
refineries, and the deregulation of the California electric market, have all
combined to allow the future Elk Hills owner(s) to be pivotal players in many
potentially profitable future financial interactions within the California
energy market.
The trend of increasing acquisition costs for producing properties could continue to record highs with this transaction. In several ways the sale will be a landmark event in the oil and gas history of Califor-nia. Virtually every major oil company and large independent made some effort to evaluate and bid on portions of the property. Selection of the high bidders has the potential of altering the future California oil and gas production environment even more than the changes of the past several years.
The Story of the Elk Hill Petroleum Reserve Elk Hills field is one of the ten largest producing oil and gas properties in the Lower 48, the largest natural gas reserve in California, and the largest natural gas liquids producer in the state. The field produces only light oil and gas from a variety of lithologies in structurally and stratigraphically complex stacked reservoirs. Although production in this "mature" field has been steadily declining over the past decade, production has been enhanced by the application of newer technologies and improved reservoir management.
The Federal Government will benefit from the fortuitous timing of the sale as potential high bidders in California are consolidating their own operations and aggressively acquiring independents. In addition, consolidated production operations that have a high net cash flow like Elk Hills are currently being valued at high prices.
The Elk Hills field is located in the southwestern San Joaquin basin, approximately 20 miles southwest of Bakersfield, California, and less than 15 miles from the surface trace of the San Andreas strike-slip fault system. The field was discovered in the early 1900s, at about the same time as nearby future giant and elephant fields such as Buena Vista, Belridge, McKittrick, and Midway-Sunset. In the 1920s the bulk of the field operations were converted into a Naval Petroleum Reserve by the Federal Government to ensure a steady supply of energy for the oil-fired boilers of the U.S. Navy. Since then the field has been jointly owned by the Federal Government (first the Navy, and now the Department of Energy), and Chevron USA. As a Naval Petroleum Reserve, the field has only really been produced during the two World Wars, and since the Arab oil embargo of the 1970s. The field operations have been managed by several operators, but current operations are run by Bechtel Petroleum Operations.
The field is centrally located in one of the richest oil and gas basins of the United States and produces from a variety of stacked Pliocene to Miocene reservoir rocks in four primary zones, all of which are productive in nearby fields. These reservoir rocks represent a variety of shallow to deep marine depositional systems impacted by the synsedimentary growth of the nearby structural highs within either a marine or a non-marine setting. Reservoir rocks range from highly porous and permeable shallow marine and turbidite sandstones, to low porosity and permeability siliceous shales and tight sandstones.
Basement Structure
The field area overlies the basement-level transition from coastal Franciscan
series rocks, which behave plastically, to Sierran granitic batholithic rocks,
which behave rigidly. This transition zone along the eastern edge of the San
Joaquin Fold-Thrust Belt results in a complicated and currently unresolved
deep structural picture consisting of at least three structures separated by
San Andreas-related strike slip fault systems. The deeper structures merge
into one large shallow anticline broken by numerous small normal tensional
fault systems.
Seismic Data and Operations
Although the operational goals of the field have been related to development
operations, many vintage 2-D seismic lines, and one recent 3-D seismic survey,
are available. The poor quality of data for both types of seismic data are a
reflection of the thick air zones in the shallow section, the ongoing
production operations, and the complex structural and stratigraphic framework
in all but the shallowest producing horizons. This situation creates an
opportunity for a technologically competent operator to better evaluate the
shallow and deeper zones for production improvements and exploratory play
definition.
Production Data
Elk Hills is a large and extensive operation. The 72 square mile unitized
operation has approximately 1,200 active wells producing over 58,000 BOPD,
350 MMcfd of natural gas, and 400 MGal/d of natural gas liquids.
Active production wells range from 1920s vintage vertical wells at a 10- to 20-acre spacing, to recent horizontal infill wells designed to produce from narrow "wedge" oil zones created in steeply dipping reservoirs between existing modern vertical wells at a 10-acre spacing. Wells range from about 3,000 to 11,000 ft in depth, and often contain multiple behind-pipe opportunities.
The reservoirs have been well managed through the interaction of the two owners and the lead operator, but recent production improvements can be related to implementation of newer technologies, increased use of modern reservoir management philosophy, and improved geological analyses and models. Most of the deeper reservoirs are pressure-maintained, either through gas injection or waterflooding projects. The operation has historically been well maintained even by California standards, with extensive amounts of investment made for field facilities and environmental compliance.
Reserve estimates from various sources are comparable in "Proved" categories, but vary in "Unproved" estimates. The complicated lithologies, stratigraphic variability, and microfaults create areas of unswept reserves in most of the reservoirs. Recently completed wells in marginal, mature production zones, have been enhanced significantly through the use of horizontal drilling and frac techniques.
Refineries and Processing Facilities
Each Elk Hills product has a unique niche in the competitive California energy
market. Unlike nearby fields with predominantly thermally produced heavy oil,
Elk Hills produces a high gravity crude sought by the independents as a diluent
for pipeline transportation of their heavy crude to refineries in Los Angeles.
The field also has the two largest gas processing facilities in California,
and is the largest natural gas liquids producer in the state.
The field contains the largest pressure-maintained reservoirs in the state, with over 2 TCF having been reinjected for improved oil recovery and NGL stripping. Eventual gas cap blowdown will impact the California gas market. Excess electricity output from the modern cogeneration facility is ready for use in the soon to be deregulated California electric market. In addition, emission reduction credits and other value areas are also present.
Operational costs and revenues for Elk Hills field are significantly different from those typically associated with California operations. The preponderance of California long reserve life heavy oil production skews the financial analysis of "comparable" California operations. Elk Hills net cash flow, revenues per employee, and BOE produced per employee are among the highest in California. Production and financial simulation models generate a very positive range of values for the property. The true value will be dependent upon the new owner(s) strategic "fit", evaluation of unproved reserves, anticipated operational cost savings, and long term price scenarios, especially for that of natural gas.
Topic Bohai Bay and Mongolian Basins of China
Speaker Changlin Wu and Don Turner, International Exploration, Kerr-McGee Corp.
Abstract The subduction of the Pacific plate under the Eurasian continent created two groups of rift basins in eastern China. The Mongolian Plateau basins, which include the Hailaer, Tamtsag, East Gobi, and Erlian basins, are in one group developed by regional extension behind the active plate margin in the Mesozoic. These basins were filled with Jurassic-Cretaceous lacustrine-fluvial sediments 3.5-4.0 km thick.
The Bohai Bay basin, part of the group of Cenozoic rift basins, was created in the Tertiary by doming and rifting caused by subduction near the active plate margin. There is over 6.0 km of lacustrine-fluvial sedimentary fill in the basin. The Bohai and the Mongolian Plateau basins share many structural and sedimentary characteristics that are typical for intraplate rift systems. Both are characterized by rapid subsidence, numerous half-grabens, active faulting, widespread volcanic intrusion, and tripartite fluvial-lacustrine facies throughout rifting.
The Bohai Bay basin has proved to be a giant petroleum province. It has reserves of an estimated 20 billion barrels in place. The Bohai basin is a good analog for the Mongolian basins in terms of tectonic evolution, sedimentary history, and hydrocarbon habitat. Buried hills, tilted fault blocks, and draped anticlines are the major structural plays. Black lacustrine shales with an average TOC of 1.8%-3.4% are the major source rocks and are thermally mature. Delta-front, subaqueous fan, deep lake turbidite, channel, and fluvial sandstones with porosity of 17%- 25% are the principal reservoir rocks. Fractured volcaniclastics and karsted carbonates are the major buried-hill reservoirs.
Commercial hydrocarbon flows have been discovered in the fluvial-lacustrine succession of the Aershan structural zone in the Erlian basin, the Lower Cretaceous sandstone of the Sotamo-19 well in the Tamtsag basin, and Beierhu-Huhehu depressions in the Hailaer basin. High hydrocarbon potential probably exists in the unexplored sub-basins of the Mongolian Plateau. The geology and exploration models in the Bohai Bay basin will enhance understanding of these frontier basins.
Biographical Sketches:
Changlin Wu is a senior geologist with the International E&P division of
Kerr-McGee Corporation in Houston and a Certified Petroleum Geologist. Before
joining Kerr-McGee, Wu was a petroleum engineer in the China National
Petroleum Company (CNPC) for eight years. He has also been a visiting scholar
at the University of London, UK, and a sequence stratigrapher at ARCO
Exploration and Production Technology. Wu received a B.Sc. degree in marine
geology from the Tsingdao Ocean University, China in 1982 and a M.Sc. degree
in sedimentology and stratigraphy from Louisiana State University in 1994.
Mr. Wu has consulted to international oil and gas companies and to the Chinese petroleum industry. He was in charge of the data package preparation for the first bidding round of China onshore blocks in 1984. He has exploration and production experiences in both onshore and offshore Chinese basins, the southeast Asian lacustrine basins, and the North Sea basins. He is currently focused on the study of petroleum systems of lacustrine rift basin and the tectonic controls of hydrocarbon generation and migration. He has published numerous papers, and abstracts in both Chinese and English.