This basic one-day course reviews the fundamental geological and physical concepts behind oil exploration using gravity and magnetic methods. It is presented in plain English with minimal math or technical jargon, and it includes hands-on exploration examples and case studies.
Delineation of regional and local fault networks, which gravity and magnetic data enable, is crucial in both conventional and unconventional exploration and production. In frontier regions, these data help to delineate the raised and subsided crustal blocks and depocenters, as well as the distribution of igneous rocks.
The course reviews all stages of gravity and magnetic survey design, as well as data acquisition and geological interpretation. These steps are put in the context of designing and executing overall exploration programs for both conventional and unconventional targets.
A complete set of course materials and lunch is included in this course.
Who Should Attend
This course is designed for professional and technical personnel who need to understand the basics of gravity and magnetic methods in order to assess their effectiveness in various exploration circumstances. The course is intended for all staff levels including geological, geophysical, administrative and management personnel.
Geological Meaning of Geophysical Anomalies: Anomaly-Lithology Relationships and Relevant Rock Properties
Forms of Rock Bodies Encountered in Oil and Mineral Exploration
Gravity Exploration Methods
Magnetic Exploration Methods
Design of Gravity and Magnetic Surveys for Geologic Targets
Processing Methods for Gravity and Magnetic Data to Separate and Enhance Desirable Anomalies
Data Display and Anomaly Enhancement
Exploration Example: Gravity and Magnetic Studies of Alberta Basement Structure
Exploration Example: Gravity and Magnetic Studies in a Frontier Basin Offshore British Columbia
Dr. Henry Lyatsky
Henry Lyatsky is a Calgary-based geophysical and geological consultant who has worked across Canada, northern and western U.S., and internationally in oil and mineral exploration.
He was born in St. Petersburg, Russia and moved to Calgary as a teenager. He holds a B.Sc. in geology and geophysics (1985, University of Calgary), an M.Sc. in geophysics (1988, University of Calgary) and a Ph.D. in geology (1992, University of British Columbia). He is the first or sole author of three books (Springer-Verlag) on the regional geology and geophysics of western Canada, two gravity and magnetic atlases of the Alberta Basin (Alberta Geological Survey) and many papers. He is a member of CSEG, MEG and APEGA.
Henry is a past president of the Mineral Exploration Group, a province-wide mining-industry association in Alberta. To avoid the downtown rat-race and congestion, he works from home, enjoys the free space of the Alberta outdoors, and loves nothing better than in-depth history books and good hikes in the mountains.
Magnetic and Gravity Methods in Mineral Exploration: the Value of Well-Rounded Geophysical Skills.
Geoscience Research & Consulting Ltd., Calgary, Alberta, Canada
The word “geophysics” in oil exploration is often used synonymously with “seismic”, overlooking many other fruitful techniques. In mineral exploration and engineering projects, applicability of seismic imaging is often limited and other geophysical methods take the front seat.
Gravity and magnetic methods, which are discussed in this article, are extremely useful in both mineral and oil exploration. Unfortunately, among oil-industry geophysicists and managers the knowledge and appreciation of these techniques tend to be comparatively thin. Rooted in over-specialized college training, a too-narrow focus on only some geophysical methods impoverishes oil exploration if potential- field surveys are underutilized. By limiting geophysicists’ ability to switch between oil and mining industries, it restricts their employment flexibility and career choices.
The multi-faceted exploration market calls for many different types of geophysical work. Professional associations and alumni groups need to put pressure on academic institutions to diversify and round out their curricula. Fluctuating economic conditions, and future well-being of new graduates, demand nothing less.
CAMAC Energy Inc. has announced that Sander Geophysics Limited (“SGL”) has completed shooting airborne gravity and magnetic geophysical surveys on the Company’s Kenya onshore Lamu Basin Blocks L1B and L16 (“Blocks”). The data acquisition covers essentially the entire 12,129 square kilometers in Block L1B and the entire 3,613 square kilometers in Block L16 and satisfies the gravity and magnetic survey requirements for each Block under the relevant Production Sharing Agreements.
The Company expects to receive initial results of the shoot in the third quarter of 2013. Results will be used to optimize the placement of 2-D seismic lines by identifying faults, basement structures and intra-sedimentary volcanic layers and/or intrusions.
“I am pleased that we completed the acquisition of the airborne gravity and magnetic geophysical surveys in Kenya safely, on time, and under budget,” said Senior Vice President of Exploration and Production Segun Omidele. “Our geophysical team will now work with SGL to interpret the data and delineate optimal areas for 2-D seismic acquisition.”
North Sea Energy Inc. announces that a 2D hi-resolution seismic program on the Norfolk Prospect (block 12/16b) (20% NSE interest) has been completed after receiving approval from DECC (UK Department of Energy and Climate Change).
The weather during November has been favourable and allowed us to acquire more data than the base plan. This will allow us to test 3D migrating the data and/or creating a Geocube product.
The processing of the additional seismic will enhance our understanding of the prospect in terms of the ‘up dip’ extent of the Norfolk prospect and assist in the determination of the drilling target. The acquiring of the seismic data this year allows us to progress our evaluation of the prospect and to make a drilling decision sooner and without delay to the project.
About Norfolk Prospect and Norfolk East Prospect – 12/16b and 12/17b
The blocks are located in the Inner Moray Firth, a short distance from the Sutherland coast. The Norfolk prospect is a large stratigraphic pinchout and dip closure of the lower cretaceous Coracle sands with additional leads in the Punt and Beatrice sands. The best estimate undiscovered oil initially-in-place of 209.0 MMstb at Norfolk and 55.5 MMstb at Norfolk East as estimated for NSE in Sproule’s Report dated July 31, 2011.
Edge Resources Inc. recently drilled two oil wells in Primate, Saskatchewan (see announcement August 13, 2012).
Based on the early successful production results in Primate, Edge has undertaken a 3D seismic program in order to fine-tune the multitude of additional drilling locations in the newly discovered Primate oil pool. The Company expects to shoot and evaluate approximately 10 square kilometers (3.7 square miles) of 3D seismic, which will add to the Company’s impressive 65 square kilometers (25 square miles) of existing, proprietary 3D seismic assets in Saskatchewan. The focus of this program is to further characterize the drilling locations in the recently discovered oil pool known as Asset East. However, the seismic extends beyond the new pool onto Edge’s neighboring 100% owned, contiguous lands, where it may reveal additional drilling opportunities.
Brad Nichol, President and CEO of Edge commented, “We were sufficiently pleased with the initial results from the two wells in Primate to shoot 3D seismic and hone the additional locations on our existing lands. The results in Primate have exceeded our expectations on many levels and production rates are getting closer to stabilizing and are continually increasing.” Nichol added, “We’re also very keen on the Grand Forks locations, which are being drilled into a well-understood, seismically-defined reservoir. We expect production to be on-stream within a few days after these wells are completed.”
Holloman Energy Corporation announces that acquisition of 127 square kilometres of a 3-D seismic data on Petroleum Exploration License (“PEL”) 112 has been successfully completed. The 3-D seismic program was executed by the Australian operations group of Geokinetics Inc. Holloman understands that the data obtained by its farm-in partner, Terra Nova Energy Inc., is of excellent quality and represents a vast improvement (in subsurface imaging) over the seismic data previously available on PEL 112.
Terra Nova has commenced seismic data processing. Once complete, the geophysical program will be interpreted with potential drill locations expected in mid-December 2012. Terra Nova is also in the process of securing a drilling rig to drill up to six wells in 2013. It is anticipated that the first well will be drilled on PEL 112, subject to rig availability, late in the first calendar quarter of 2013. Under the terms of its farm-in agreement on PEL 112 and PEL 444, Terra Nova is required to place AUD$4,500,000 in escrow on November 1, 2012 to support the upcoming drill plan.
News released by Cooper Energy earlier this month confirms the continued success of their drilling efforts on the Cooper Basin’s western flank. Cooper Energy reported that the success of it Butlers-5 oil well in PEL 92 has been followed by similar results from its Butlers-6 well. Each well penetrated gross oil columns ranging from 5 to 8 metre in the Namur Sandstone and have been suspended for completion as oil producers. The oil finds on PEL 92 are situated 25 kilometres north/northwest of PEL 112 on lands believed to be of a similar geological model.
On PEL 444, Terra Nova is in the process of designing a 150 km2 3D seismic program for completion in 2013.
The Cooper Basin’s most productive sediments for petrochemicals were formed during the Permian period, which ended about 250 million years ago. Since the end of this era, the Permian’s rich organic sediments have been increasingly buried under additional layers of rock, thus forming deposits of coal, oil, natural gas, and other petrochemicals.Because of the geological history of the Australian continent, the Permian sediments in Central Australia primarily occurred in one distinct region – the Cooper Basin. This basin is surrounded by and underlies a portion of the much larger Eromanga Basin, which is mostly comprised of younger sandstones and sediments from the more recent Jurassic and Cretaceous periods. It is these younger formations that overlie the Cooper Basin’s Permian sediments, thus trapping (or “capping”) the petrochemicals underground and creating Australia’s richest oil and gas producing region. There has been a recent surge in drilling activity for oil in the last five years with many new Jurassic Eromanga discoveries being made along the southwestern flank of the Cooper Basin
Vanoil Energy Ltd. announces it has completed its 2011 2D seismic program on Block 3B in Kenya. Vanoil’s 100% owned Blocks 3A and 3B in Kenya cover approximately 24,000 square kilometres and are part of the vastly under-explored prolific Cretaceous Central African Rift Basin System in Kenya.
Vanoil’s 2011 seismic program in Block 3B covered approximately 398 line-km and was completed on budget and schedule. The program was designed to cover several leads previously identified on the re-processed 1975 Chevron and the 2010 Vanoil seismic data in Block 3B. The 2011 seismic data is high quality with location, time and amplitude content having been jointly assessed and controlled by the contractors; Bureau Geophysical Prospecting [BGP] and RPS. This premium data has been gathered to further image some specific structural leads and as a reconnaissance programme to identify more new leads in Block 3B. In addition, the 2011 seismic program was also designed to enable Vanoil to improve on the geologic model in the Lamu Basin, one of the three basins identified on the Vanoil Blocks.
The 2011 2D seismic program in Block 3B consisted of 398 kilometres of additional seismic bringing the cumulative total to 845 kilometres of 2D seismic coverage completed by Vanoil to date on Blocks 3A and 3B in 2010/2011.
The 2011 Vanoil 2D seismic programme data will now be sent to Statcom in Calgary Alberta for processing, following which, the data will be interpreted and integrated with the reprocessed and interpreted 1975 Chevron and 2010 Vanoil data. With the newly acquired data, the Company expects to add significantly to the resource assessment incorporated in the previously announced Sproule 51 101 report.
Most of the Block 3B acreage is located in the Lamu Embayment with a small portion of the block to the northwest probably in the Anza basin. It is also possible that a small area of Block 3B to the northeast is located in the Mochesa basin. The Lamu Embayment basin was initiated in the Karroo [Permo-Triassic] times during which an intra-cratonic, tri-radial rifts system developed in East Kenya. This development of the triple junction rifts system heralded the emergence of proto Indian Ocean and culminated in the failure of one of the rift branch which today constitutes the onshore Lamu Embayment basin. The failed Karroo rift extends to the Block 3B acreage. During the subsequent basin-fill in Block 3B the Karroo sequences have been buried thousands of meters below the oil window. During the Jurassic period, Block 3B area experienced marine transgression into the initial Karroo rift-graben which was accompanied by the deposition of mainly marine carbonates and minor shales under platform depositional systems. Faulting in Block 3B continued to Late Mesozoic and Lower Tertiary with emerging rift depo-centers being filled primarily by sediments deposited under fluvial-lacustrine, deltaic and marine depositional systems. The eastern portion of the Block 3B acreage was under marine influence in Middle Cretaceous during which potential source rocks shales and marine carbonates were deposited. During the lower Tertiary, non-marine continental depositional systems were extensive and similar throughout the Block 3B acreage. In the Upper Tertiary however, the southeastern portion of the Block 3B was under marine transgression that resulted in the deposition of Lower to Middle Miocene marine reefal carbonates, sands and shales. The marine transgression barely reached the Anza graben in the Block 3A. In Block 3B, the Lower-Middle Miocene marine sequence is capped by Pliocene to Quaternary coarse fluvial deposits.
TGS has commenced a new 1,000 km multi-client 2D survey in Northeast Greenland in partnership with Fugro.
This survey will enable customers to prepare for the announced Greenland Licensing Round in 2012/2013 and will significantly add to a data set that TGS has been growing since 2008 in this promising region. After this year’s data acquisition, TGS will be able to offer approximately 4,500 km of new multi-client 2D data, a large volume of reprocessed multi-client 2D data and full coverage of aeromagnetic/gravity data over the basins that are to be included in the planned licensing round.
The new seismic data is being acquired by the M/V Akademik Shatskiy supported by the ice breaker M/V Fennicia and is scheduled to complete during Q4 2011. Data processing will be performed by TGS and data will be available to clients during Q1 2012.
Interview with Dr. Michal Ellen Ruder, Wintermoon Geotechnologies Inc on the use of gravity and magnetic methods for Oil and Gas exploration.
1. Under what conditions will gravity methods outdo seismic? Why?
2. In what situations are gravity methods absolutely indispensable if you want results?
3. Can you describe some cases where seismic and gravity methods complement one another?
4. What techniques have you personally developed or enhanced?
5. Gravity/magnetic methods used to be used mainly to tell an explorer where to best place seismic. Nowadays you’re advocating its use as complementary and integrative to seismic as well. What has caused the shift?
6. What has been the hottest development in the past two years with respect to using grav/mag in oil and gas exploration?
“Discovering and assessing oil or gas deposits requires integration of information culled from geology, geochemistry, drilling, GIS, seismology, EM, potential fields, and other disciplines.
While seismic exploration remains the primary method of exploring for petroleum, use of gravity and magnetic methods has continued to expand, based on their contribution to reliable evaluations (and recent discoveries) in deeper, more challenging environments such as sub-salt structures and deep sea.”
Advances in processing and interpreting gravity and magnetics
Applying gravity and magnetics in deepwater exploration
Effective use of gravity and magnetic data for oil exploration
Shell and HP have announced a breakthrough in the capability of their jointly developed inertial sensing technology to shoot and record seismic data at much higher sensitivity and at ultra-low frequencies.
The new onshore wireless seismic acquisition system is designed to provide a clearer understanding of the earth’s subsurface, thus increasing prospects for discovering greater quantities of oil and gas to meet the world’s increasing energy needs.
The sensing technology has now been demonstrated to have a noise floor – a measure of the smallest detectable acceleration over a range of frequencies – of 10 nano-g per square root Hertz (ng/rtHz), which is equal to the noise created by the earth’s ocean waves at the quietest locations on earth as defined by the Peterson low noise model. The tests were conducted in the seismic testing vault at the US Geological Survey’s (USGS) Albuquerque Seismological Laboratory facility in New Mexico.
The seismic system uses the breadth of HP’s technology development capabilities as well as Shell’s advanced geophysical expertise in seismic data acquisition systems and operations. As such, this collaboration builds on the core strengths of each company to advance technology in this field.
The system will be delivered by HP Enterprise Services and the company’s IPG. It is based in part on the high-performance sensing technology originally co-developed by HP Labs – the company’s central research arm – along with IPG and Shell research in seismic network design.
Fig. 1. The survey will be flown using BlueQube technology.
Shell Chief Scientist for Geophysics, Dirk Smit, discusses how innovative technologies — sometimes developed in unusual R&D partnerships — help energy companies to explore for harder-to-find oil and gas resources.
TGS will commence a new multi-client 3D survey in the Tarakan Basin, offshore East Kalimantan, Indonesia in the Celebes Sea. The survey, TBN10, is the first ever multi-client 3D survey for TGS in Indonesia waters and will cover in excess of 1,600 km2. The data will be acquired by the M/V Seisquest and will commence before the end of this year, with acquisition expected to complete in Q1 2011.
The TBN10 survey will be conducted over the highly prospective and extensive play fairway which includes a recent gas discovery. The new 3D seismic will provide improved stratigraphic and structural resolution of the Tarakan sub-basin, leading to a better understanding of its petroleum system and a much clearer definition of the numerous leads and prospects already identified on existing 2D seismic in the area.
“TGS is particularly excited to announce this new 3D program, stated CEO Robert Hobbs. The company has built significant experience in this region through our long-term investment in data that informs our customers about the potential of this frontier region. This 3D project confirms the further maturation of this important hydrocarbon province.”
The TBN10 multi-client 3D survey is supported by industry funding and also supports the Indonesia government’s overall objective to attract exploration and raise declining production levels.
Michael Galbraith, Vice President of Seismic Image Software, a Division of GEDCO. Mike has made profound contributions to the science of designing 3D seismic surveys, beginning with his first 3D design program in 1985. Internationally, he is one of Canada’s best known geophysicists because of his teaching – over 70 courses taught over the last 12 years in all corners (well – almost all!) of the world ( http://www.cseg.ca/about/awards/honorary/Mike-Galbraith.cfm).