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PGCE 2009
- Conference date: 01 Mar 2009 - 03 Mar 2009
- Location: Kuala Lumpur, Malaysia
- Published: 01 March 2009
1 - 20 of 32 results
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Fractured Basement Formation Evaluation Using Borehole Data
Fractured basement reservoirs are amongst the most difficult types of reservoir to evaluate. Yet, of all
reservoirs, they are the most important to evaluate early in the field life cycle to minimise the costs of drilling
unnecessary wells. It is essential to acquire important fracture characterization data early in order to optimise
future well locations and paths, to predict field rates and recovery, and to economically deplete the field.
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Building More Predictive Geological Models
Authors Carl Hedvall and Mark SamsA majority of oil companies today build geological models mostly from well data making these
models detailed and reliable near the wells, but away from the wells little or no information is available. Many
oil companies have invested in seismic data and interpretation of that data; data that contains information that
could increase understanding of inter well properties, improve geological models and thereby reduce reservoir
uncertainty. But despite existing “Seismic to Simulation” software few oil companies integrate 3D seismic
properties with geological models. Even if they do, critical aspects of the reservoir may be lost or distorted
when they transfer data from the seismic grid to the geological grid. This in turn can result in erroneous
prediction of reservoir and net pay.
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The Monte Carlo Myth, Or Why A Reservoir Isn’t A Roulette Wheel
More LessInvestigations into reservoir uncertainty are becoming more commonplace, not just into reserves or
static uncertainty but also into the behavioural uncertainty associated with the flow characteristics of the
reservoir. Unfortunately many of these investigations rely on two assumptions; 1) that the input property
distributions can be defined by normal distributions and 2) that Monte Carlo methods are applicable for the
analysis of multivariate relationships (particularly those of spatial properties). These two assumptions have
long been abandoned in other areas of uncertainty modeling and risk assessment, most noticeably in financial
engineering.
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Unconventional Gas Resources – Do Paradigms Need To Change?
By Doug KenaleyThe relatively mature state of global hydrocarbon exploration combined with increasing global energy
demand and challenged accessibility to areas of significant conventional potential has caused industry to focus
in additional resource arenas such as unconventional gas. While the recent flurry of announcements in North
America unconventional plays involving tight gas, shale gas and coal bed methane may seem monumental to
some, it is really only a reflection of the continuing evolution of the hydrocarbon extraction industry.
Emerging information from many of these plays appears to challenge some established industry paradigms.
Modifications to the technical approach used to identify, characterize and successfully manage some of these
resource types may need to be considered.
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Coalbed Methane( CBM) Prospect In Jamalganj Coal Field, Bangladesh
More LessMethane and coal are formed together during coalification, a process in which plant biomass is
converted by biological and geological forces into coal. The Methane that is stored in coal seams and the
surrounding strata are released during coal mining.
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Relationship Between Gas (CO2) Traps And Structural Styles In The Al Jamouse Area, Melut Basin, Sudan
Authors Huzaifa A. Baseeiry and Shahrul Amar AbdullahOne of the recent exploration challenges in the continental rift basins of Sudan is the flushing effects
of hydrocarbon (oil) from the structural traps by carbon dioxide (CO2). This presentation will show some
examples from the most prospective traps in the Melut basin (half graben basin) (Fig.1) of Sudan that proved
this phenomenon. These prospects were originally categorized as the high rank drilling candidates in term of
the size and petroleum system elements (source rock, reservoir rock, trap, migration, timing…etc).
During drilling, good and continuous hydrocarbon shows were encountered along the targeted
reservoir intervals of the Adar and Yabus/Samma sands (Tertiary Reservoirs) in the kitchen area (Fig.2a).
However, the formation evaluation (e-log) confirmed that the zones were gas bearing (from the densityneutron
cross-over and pressure gradient plot) (Fig2b). Production tests were performed on the potential gas
hydrocarbon zones. The tests results concluded that the reservoirs were filled with carbon dioxide (CO2) rather
than hydrocarbon gas bearing (up to 90% CO2). As the result, the prospectivity of this area was downgraded
and the exploration strategy was subsequently changed.
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Reservoir Monitoring, 4D Signal, And Fiber-Optic Technology
Authors Steve Maas, Rune Tenghamn, Brett Bunn, Natasha Hendrick and Mazin FaroukiOne of the challenges faced by reservoir engineers is to understand the way fluid saturation, pressure
and compaction change between wells during production of a hydrocarbon reservoir. The optimum placement
of infill wells and identification of new step-out opportunities to maximize recovery of hydrocarbons depends
on such information. Time lapse (or 4D) seismic is acknowledged as being the only direct wide-scale
reservoir management tool capable of revealing these important details about a producing reservoir. The Life
of Field Seismic (LoFS) project at the Valhall field on the Norwegian continental shelf illustrates the technical
and economic success of reservoir monitoring using 4D seismic data. Today, as the industry explores, drills
and produces deeper and more challenging targets, reliable and consistent reservoir monitoring is becoming
even more essential. A new fiber optic seafloor seismic acquisition system – with high dynamic range, low
background noise, low cost per channel and a long operational life – is leading the way towards cost-effective
permanent seismic reservoir monitoring.
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Beam Depth Migration For Imaging Of Complex Geology
Authors Karl Schleicher, John Sherwood, Lynn Comeaux and Mazin FaroukiKirchhoff migration has traditionally been the leading implementation for application of depth
migration to seismic data. There are many reasons for this, such as efficiency, ability to image steep and even
overhanging dips, and flexibility. In most parts of the world Kirchhoff migration produces images that are as
good as, or better, than the more expensive implementations using downward continuation algorithms.
However, the limitations of Kirchhoff migration are well known and its inability to image more than a single
arrival is the most damaging. Downward continuation algorithms, on the other hand, handle all arrivals but
their inability to image steep dips is a severe limitation.
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Mitigation Of Drilling Risk Using Controlled Source Electromagnetic Surveys: Csem Workflow And Case Study
Authors Lars Lorenz, A. Muralikrishna, Anil Kumar Tyagi, Rabi Bastia and Hans E. F. AmundsenRemote sensing of hydrocarbon reservoirs using controlled source electromagnetic (CSEM) surveys is a
powerful tool in de-risking exploration prospects. This study illustrates the general workflow for the planning,
execution and interpretation of seabed logging (SBL) surveys, and shows how the data set is utilized by
Reliance in the selection of drilling targets in the East Coast Deep Water blocks, resulting in a significant gas
discovery.
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Marine Magnetotelluric (Mmt) Mapping Of Basement And Salt Bodies In The Santos Basin, Brazil
Authors Sergio L. Fontes, P. de Lugao, Max A. Meju, V.R. Pinto, E.U. Ulugergerli, E.F. La Terra and L.A. GallardoThe marine magnetotelluric (MMT) method is rapidly emerging as a practical electromagnetic tool for
investigating the deep resistivity distribution beneath the sea-floor and aid the exploration for hydrocarbons
especially in areas of poor-seismic data. Remarkable advances in field instrumentation over the last few years
now permit the use of MMT for hydrocarbon exploration in the marine environment (Constable et al., 1998;
Sandberg et al., 2008). The MMT method has been successfully used to achieve marine exploration objectives
such as imaging sub-basalts, carbonates and subsalts in situations where seismic imaging is poor. The high
contrast in electrical resistivity between salt bodies and the surrounding sediments makes for a good target and
provides an opportunity to test the applicability of the MMT method in oil exploration studies. The deep water
basins in offshore Brazil are the sites of giant oil and gas discoveries, and should provide excellent test sites
for evaluating the MMT method.
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Near Surface Resistivity Responses To Lithostratigraphy And Fluid Contents
Authors Zuhar Tuan Harith, Ani Aiza Ashaari and Rosli SaadResistivity variation is an important physical property to investigate near surface structures such as
salt water intrusion, sinkholes, cavities, as well as active faults. The electrical property of the rocks is severely
affected by pore connectivity and fluid type, thus their subsurface variation can be an indicator of the
subsurface geology and its fluids. Shallow fractures, faults, and unconformities are expected to have low
resistivity as they normally behave as conduits for ground water flow. However when those fractures and
faults were filled with resistive fluid (such as liquid hydrocarbon and gas), it should reads a high resistivity.
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The Effect Of Resistivity Anisotropy On Earth Impulse Responses
Authors Folke Engelmark, Bruce Hobbs and Dieter WerthmüllerResistivity anisotropy arises through a variety of scales from micro (e.g. grain size, pore water
connectivity) to macro (e.g. laminated sand-shale sequences). For general anisotropy the physical property
under consideration may vary in all three spatial directions. The simplest problems involve transverse
anisotropy where resistivity at a point in any direction in a plane differs from the value perpendicular to the
plane. We are here concerned solely with transverse anisotropy with a vertical axis of symmetry (TIV) so that
resistivity at a point has a constant magnitude in any horizontal direction. Induction logs, laterolog and LWD
(logging-while-drilling), at least in vertical wells, may be used to examine TIV in particular and these well log
results often differ from indirect determinations of resistivity through DC resistivity and general EM
surveying. Much of the earlier EM literature considered resistivity as isotropic but there is now great emphasis
on the inclusion of anisotropy in modeling and inversion studies. In this paper we consider the effects of
transverse anisotropy (specifically TIV) on the earth’s electromagnetic impulse and step responses.
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Offshore Geohazards Investigation - Can We Do Without?
More LessThe E&P companies are experiencing challenges with offshore geohazards during their quest for
hydrocarbon resources. Offshore geohazards have a direct impact on safety and cost of drilling operations,
offshore facilities design installation and production.
Offshore geohazards are defined as natural and man-made seabed and sub-seabed features with
potential risk to cause damages to assets, environment, health and even loss of lives. Offshore geohazards are
grouped into three main categories that are namely: seabed hazards, shallow hazards up to 200m sub-seabed
and intermediate hazards up to 1000m sub-seabed.
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Genetic Inversion: An Innovative Combination Of Neural Nets And Genetic Algorithm For Seismic Inversion
Authors Jumain Marzuki, Jimmy Klinger, Ivan Priezzhev, Trond H. Bo and Gaston BejaranoA new approach to derive an Acoustic Impedance Inversion volume is proposed in Petrel. Multi layer
neural networks as well as genetic algorithm are combined together in order to provide a robust and straight
forward seismic inversion.
Estimation of rock properties using seismic data and derived attributes has always been a very
important but challenging task. There are several "schools" using different methods in order to achieve this
goal. All of them are based on strong and constraining a-priori information. The required knowledge of an
initial model (cf. for the stochastic inversions), or source wavelet (cf. Colored-, Sparse Spike Inversion), is in
several cases hard to acquire, if not even impossible. Moreover, the result of this kind of inversion is often
biased by the input initial model itself.
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Coaxing Subtleties From Seismic By Means Of An Intelligent Integrated Approach – A Case Study
Much information is contained in the seismic reflectivity signal. The discernment between signal and
noise, and the reduction of ambiguity of these signals is a major technical challenge. Interpreting lithology
solely on normal seismic reflection strength has been well recognized to have pitfalls. This paper sets a case
history of coaxing the subtle relevant data out from the seismic signals by means of an intelligent integrated
approach.
It is current industry standard, with the availability of fast cost effective computer systems and data
storage, to have outputs of a number of seismic data versions besides the traditional full stack seismic data.
The ability to cohesively analyze all the available data in a timely manner makes the difference on the
economics of petroleum exploitation from exploration through to the development phase. The result of each
separate analysis should also converge for the deductions to be considered valid for interpretation.
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Rapid Multiple-Scenario Depth Structure Risk Analysis Case Study In Cuulong Basin, Vietnam.
Authors Hong Shien Lee and Nguyen Xuan NamDepth conversion uncertainty is a critical factor for drilling fractured granite basement targets with
highly deviated well trajectory in Cuu Long Basin, Vietnam. This paper illustrates depth conversion using 3D
velocity model that calibrates many sources including seismic velocities, time depth functions, well picks and
surfaces. Various assumptions of velocity interpolation employing different data inputs were evaluated
systematically in order to see their effects on the model. Four sensible assumptions were chosen to generate
“what if” scenario velocity models to capture the uncertainty. Case study done on this area using the method
described above has produced the base case or “most likely” case, the high case and the low case. The result
suggests that actual basement depth is deeper than previously predicted. The previous velocity model used
was created based on single time-depth function from a nearby well.
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Geomechanical Modelling, Seismic Pore Pressure Prediction And Wellbore Stability Analysis: Key Elements Demonstrated By An Offshore Exploration Case Study
Authors Adrian White, Sunil Nath, Katharine Burgdorff and Norbert van de CoeveringA robust, field-specific geomechanical model (in situ stress, pore pressure and rock properties –
Figure 1) has proven to be an essential tool for the hydrocarbon industry. Constraining the geomechanical
model for any particular area provides valuable information for improved characterisation of the region, field
or reservoir. The geomechanical model can also help to support a development plan that optimises drilling and
production operations. The benefits of incorporating a geomechanical approach into the well planning phase
include predicting pore pressure, fracture pressure, wellbore stability and minimising the use of excessive mud
weights that may lead to formation damage.
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Exploration And Production Geoscience In The 21St Century: Challenges And Opportunities
By Kurt RudolphThe world’s economy is dependent on energy. To support continued economic progress for the
world’s growing population, the world’s total energy demand is expected to grow significantly over the next
twenty years. Global demand will be met by a variety of energy types. However, fossil fuels will continue to
provide close to 80 percent of energy supplies over the period to 2030, with oil and gas accounting for more
than half.
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Keys To Success In Unconventional Shale Gas Resource Plays
More LessUnconventional resource plays such as shale gas, coal bed methane, tight gas sands and heavy oil
sands developed rapidly from 2004 to mid 2008 due to high energy demand, high prices and technology
advancements.
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Adapt or go Extinct - The Rapidly Evolving E&P Landscape
More LessIn the landmark book On The Origin of Species by Means of Natural Selection published in 1859,
Charles Darwin wrote “It is not the strongest of the species that survives, nor the most intelligent, but the one
most responsive to change.” Change is universal in the natural environment. It occurs at all scales and nothing
is immune. Examples range from global atmospheric temperature to crust composition and weathering rates.
All of these have changed through geologic time.
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