ACTUAL THEMES AND APPLICATIONS

* In the second August 2011 News an Article of

Gene Ballay

Now you see it, now you don´t
Highly deviated wellbores sometimes suffer from a cyclic variation in borehole size.
And although the caliper oscillations may be relatively small (+/- 1/4" for
example), when combined with a salty mud the composite can severly compromise the borehole wireline data. Curiously, it may be the deepest reading tool (resistivity) which suffers the largest degradation, with the pad bulk density data being less affected than the mandrel neutron porosity.
The situation may be understood, and a remedy devised, within the context of the Fourier Transform.
The Fourier Transform of the caliper log, across the interval of cyclic wellbore, will contain a peak at the frequency (depth wavelength) corresponding to the cyclicity of the hole size.
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* In the August 2011 News an Article of

Ralf Oppermann

A new workflow for high-resolution fault imaging
delivers groundbreaking insights into resource
operations and recoveries

Fault and fracture networks can have significant effects on drilling, mining and the safety of resource operations.

Due to this, various automatic fault extraction techniques have been developed for 3D seismic data in recent years. These techniques aim to support or (partially) replace manual fault mapping efforts, which are typically labour-intensive, time-consuming and subjective.
This paper presents innovative techniques and workflows that have been developed to integrate 3D seismic visualization and highest-resolution image processing results with the detailed calibration and review of various seismic, well and mining data.

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* In the July 2011 News an Article of

Ralf Oppermann

A new method for high-resolution fault imaging delivers groundbreaking insights into drilling and production of resources

Novel techniques and workflows in automated fault extraction have been developed to visualise faults at extremely high resolution from 3-D seismic data, and to subsequently evaluate how these faults can impact
resource activities (drilling, mining), resource recoveries (e.g. oil & gas, coal) and the safety of operations (e.g. gas kicks, outbursts).
Examples from resource projects around the world demonstrate that new methods in fault imaging can deliver groundbreaking insights into the drilling and production of resources.
These insights often challenge current perceptions:
Presently, most 3D surveys in the resource industries are underutilized with respect to the detailed delineation of faults in the subsurface.
- The increased fault resolution results in a dramatic increase in the number of faults that are identified from seismic.
- There are a lot more faults penetrated in wells than realised industry-wide, and these faults can cause a number of drilling and production problems, or production opportunities.

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* In the June 2011 News an Article of

Gene Ballay

Averages

As geoscientists, our attention is often focused on foot-by-foot calculations (and associated “noise”) and there is a tendency to regard the average values (which will be used for simulator initialization,
reserves estimation, etc) as being subject to the same uncertainty as the foot-by-foot values, when in fact the layer averages may be significantly better known.
In most evaluations, the Log Repeat seldom receives any attention beyond possibly a simple comment such as ‘repeat looks reasonable’. Were we to take the time to digitally load the Repeat and compare it to
the Main Pass in both the foot-by-foot and average value sense, we would not only be able to better QC each logging run individually, but we could also estimate the uncertainty present in the layer average
values.
The situation has been illustrated with a physically realistic Monte Carlo simulation of Phi(Rhob).

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* In the April 2011 News an Article of

Gene Ballay

In Search Of The Biggest Bang For The Buck

As Geoscientists, we are accoustomed to facing uncertainty,
and thus often provide not only a Best Estimate, but also both
Up- and Down-side. In fact, however, while this simple and useful
characterization is a step in the right direction, it can be
improved upon in a manner that recognizes:
•It is unlikely (but not impossible) that the various input
  High- and Low-Side values will occur simultaneously.
•The individual input attributes (Rw, Porosity, etc in Archie’s
  equation, for example) are linked, and a change in the uncertainty
  of one can affect the impact that another has on the ultimate estimate.
•Determines which of the input attributes is dominating uncertainty
  in the ultimate estimate, for each specific combination.
There are two basic alternatives to the High- and Low-Side approach,
partial derivatives and statistical simulation, that complement one
another.
Here the issue is illustrated with Archie’s equation, but the concept
is general, in that once understood it may be applied to many of the
issues that we face day-to-day (routine and special core analyses,
conversion of Pc(Lab) to Pc(Reservoir), Saturation(Height), Reservoir
Volumetrics, etc).

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* In the January 2011 News an Article of

Gene Ballay

What You See, Is What You Get

And what you see may depend upon how you look at it.

Did you ever have one of those ‘lightning bolt out of the blue’ experiences?
The data is just not fitting together, and one hypothesis after another has
been discarded, when suddenly ‘the light bulb comes on’.
In many cases, it is a revision of our mental (and analytical) vision that
unlocks the puzzle.

In order to evaluate alternatives, we need the vision (mental and graphical), and the data in digital form. But it’s not uncommon to be presented with a graphical summary (published literature, historical report, etc), absent a digital tabulation of the data itself, and in such a situation we are handicapped from the start. And here I recently experienced one of those ‘bolt out of the blue’ experiences when my colleague Shameem Siddiqui (Texas Tech) pointed me to the shareware at sourceforge.net, specifically the engauge digitizing software (sourceforge.net/projects/digitizer/files/).

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* In the December 2010 News an Article of

Renate Pechnig

Integrated geological and geophysical studies in the SG4 borehole area, Tagil Volcanic Arc, Middle Urals: Location of seismic reflectors and source of the reflectivity

Near-vertical incidence reflection seismic data acquired in the Tagil Volcanic Arc (Middle Urals) show the upper crust to be highly reflective. Two intersecting seismic lines located near the ongoing ~5400 m deep SG4 borehole show the main reflectivity strikes approximately N-S
and dips ~35° ~55° to the east.
Prominent reflections intercept the borehole at ~1000,~1500, ~2800, ~2900, ~3400 and between ~4000 and ~5000 m,which correspond to intervals of low velocity/low density/low resistivity.
The surface projections of these reflections lie parallel to the strike of magnetic anomaly trends.

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* In the November 2010 News an Article of

Renate Pechnig

Integrated log interpretation in the German Continental Deep Drilling Program: Lithology, porosity, and fracture zones

Well logs, aquired in the two scientific drill holes of the German
Continental Deep Drilling Program (KTB), provide continuous records
of physical and chemical data of the metamorphic rocks penetrated.
The 4-Km-deep pilot hole was almost completely cored, enabling the
well logs to be calibrated with regard to rock composition and
structural features derived from laboratory analysis of cores.
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* In the October 2010 News an Article of

Bjorn Paulsson

Fiber Optic Geophones for Oil and Gas Field Applications

IWe are presenting a new fiber optic sensor system implemented as a

Fiber Optic Geophone (FOG).  We are presenting the design and experimental test results for the FOG and compare its performance with regular exploration geophones and geophones used for scientific
investigations. We will demonstrate that the new Fiber Optic Geophone (FOG) has a significantly better performance than the current state of the art coil geophones in terms of noise floor, sensitivity and frequency response.

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* In the September 2010 News an Article of

Jean-Paul Chilès

Modelling the geometry of geological units and its uncertainty in 3D from structural
data: The potential-field method

IMost 3D geological modelling tools were designed for the needs of the
oil industry and are not suited to the variety of situations encountered in
other application domains. Moreover, the usual modelling tools are not
able to quantify the uncertainty of the geometric models generated. The
potential-field method was designed to build 3D geological models from
data available in geology and mineral exploration, namely the geological
map and a DTM, structural data, borehole data and interpretations of the
geologist.

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* In the August 2010 News an Article of Gene Ballay

One-Two-Three, What Do We See

In today’s world of powerful laptop computers and visualization software, geoscientists routinely produce and rotate three dimensional graphics as a part of the interpretation process. Hardcopy documentation, however, remains vital and is in two dimensions. Here, the ternary plot fills a niche, somewhat similar to (but more sophisticated than) the histogram, in that it summarizes the relative simultaneous values of three components (whereas the histogram summarizes a single attribute) in a two dimensional format. The display may additionally serve as a kind of Quick Look Fingerprint that allows one to visually recognize similar three dimensional combinations.
As carbonate petrophysicists, ternary plot applications include (but are not limited to);
1. Relative concentrations and relationships of three mineral assemblages (for example calcite, dolomite, anhydrite),
2. Bulk volume porosity – mineralogy relations (porosity, calcite, dolomite),
3. Porosity partitions (micro, meso, macro).

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* In the June 2010 News an Article of John Fanchi

Green Field Flow Modeling Workflow

Different workflows exist for designing, implementing and executing reservoir asset management projects. A typical workflow needs to identify project opportunities, generate and evaluate alternatives, select and design the desired alternative, implement the alternative, operate the alternative over the life of the project, including abandonment, and then evaluate the success of the project so lessons can be learned and applied to future projects. Reservoir flow models, which are also known as dynamic models, can play a significant role in comparing alternatives, selecting the optimum reservoir management plan, and assessing the success of the project as it is being implemented and operated. A modern flow modeling workflow for green fields is described below for an oil field.

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* In the May 2010 News an Article of Kurt Marfurt

SEISMIC ATTRIBUTE ILLUMINATION OF WOODFORD SHALE AND
FRACTURES.     ARKOMA BASIN OK

Shale gas is one of the most promising unconventional resources
for hydrocarbon exploration and production. Open fractures in
shale provide critical porosity and permeability, while healed
fractures can be opened for hydrocarbon flow through
carefully-designed hydraulic fracturing programs.
Recent technical and economic advancement in horizontal drilling
techniques have made the Mississippian and Devonian Woodford Shale deposited over a large portion of the Midcontinent a significant
hydrocarbon play.
To date, the major use of 3D seismic data in the study of shale
gas reservoir has focused on (1) mapping natural fractures (and
karst) that can provide enhanced conduits for hydrocarbons (and
in the Barnett shale for water from the underlying Ellenberger),
and (2) mapping geo-mechanical brittleness and horizontal stress
directions for effective hydraulic fracture stimulation.
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* In the April 2010 News an Article of Gene Ballay

VISUAL  BASIC

You can't depend on your eyes when your imagination is out of focus (Mark Twain).

Today’s sophisticated software offers unprecedented formation evaluation capabilities, but just as Mark Twain opined 100 years ago, the full benefit will not be achieved unless we have a clear understanding of the underlying inter-relationships, and a
focused vision with which to interpret the results.

Simple visual patterns can signal (and more)

* are (independent) laboratory measurements internally consistent    with one another, and the wireline data,

* whether an interval is wet or hydrocarbon bearing,

* locally appropriate values for Rw, ‘m’ and ‘n’,

* is there a ‘short circuit’ risk to Sw(Archie).

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* In the March 2010 News an Article of Steve Hill

WHY 3D SEISMIC  ?

3D seismic data is significantly more expensive than 2D seismic data. What do we obtain for the extra expense ?  2D data assumes no out-of-plane structure where surface locations of the 2D data define the “plane”. In other words, 2D data assumes no lateral variation in the reflectors perpendicular to the 2D plane.

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* In the February 2010 News an Article of Robert Garotta

SHEAR WAVES FROM VIBRATORS

Relationships between shear waves and vibrator sources are somewhat conflicting and amazing.

Manufacturers easily made the mass vibrating  horizontally but the problem of the horizontal vibrator is coupling: inversed pyramids or vertical blades are necessary to transmit horizontal stresses.

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* In the January 2010 News an Article of Gene Ballay

STATISTICS ARE PLIABLE

Facts are Stubborn, Statistics are more Pliable: Mark Twain said it, and while we all realize it,the fact remains that in a busy environment the implications can slip past us. And the risk is

compounded when one recognizes that the default algorithms / display formats for some oilfield data, may lend itself to an improper numerical evaluation.

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* In the December 2009 News an Article of Tim Smith

THE LONG WAY TO A SUCCESSFUL SEISMIC INTERPRETATION

In 2007 BHP Billiton acquired a 2900 sq km leasehold in the northwest Florida shelf in water depths of about 1 to 1.25 km.

This acquisition was based on interpretation of a 12,000 km 2D seismic dataset which had been processed through pre-stack depth migration; these data became available in 2006.

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* In the November 2009 News an Article of Gene Ballay

SPLIT PERSONALITY

Carbonates and sandstones differ in a number of fundamental ways (Gene Ballay. 2005), with consequences that affect the techniques required for their evaluation (Chris Smart, 2003). One outcome of these differences is the likelihood of a multi-mode porosity system in carbonates, which in a manner akin to that thriller Dr Jekyll and Mr Hyde, can consist of pores that are almost art from a visual perspective, but become sinister when one is charged with correctly evaluating the reservoir.

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* In the October 2009 News an Article of Robert Garotta

WHAT TO EXPECT FROM VECTOR WAVEFIELDS  ?

Multi-component experimentations started around forty years ago, using primitive acquisition or processing tools, when compared to the complexity of the shear mode propagation. Slow but substantial advances of the field techniques and digital processing now open the way to the real potential of multi-component technology provided the process respects all necessary conditions. Pure shear mode surveys are rare, multi-component technology presently considers PS mode in addition to the P mode.

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* In the September 2009 News an Article of Robert Garotta

DETECTION and COMPENSATION of the BIREFRINGENCE

The effects of birefringence or shear wave splitting on a single raypath recorded with a good signal-to-noise ratio can be easily described and formalized, offering a way of deriving birefringence attributes: natural orientation, percentage of azimuthal anisotropy and differential attenuation.

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* In the July 2009 News a new Article of Gene Ballay

           ROLLING the DICE

There are two basic ways in which the issue of uncertainty can be characterized; partial derivatives of the expression of interest (Sw in this situation) and Monte Carlo simulation. At the simplest level, they complement one another, and since each are easily coded into an Excel spreadsheet, we routinely perform both, as a QC cross-check.

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* Filling with Petrophysical Properties

* In the June 2009 News the Paper of Helene Beucher and

Didier  Renard:  FILLING WITH PETROPHYSICAL PROPERTIES

One of the main challenges of geostatistics in reservoir characterization is to populate a portion of 3-D earth model with its petrophysical properties. This operation must be carried out while still honoring the information available along well logs: in our jargon,
we say that it must be conditional.

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* In the May 2009 News the Paper of Gene Ballay

Multidimensional Petrophysical Analysis in

the Reservoir Description.

During the development of the Shaybah Field in the Empty

Quarter of Saudi Arabia, a number of wells were cored and logged with a routine open-hole suite of tools (density-neutron, sonic-resistivity), and then later (but preproduction) logged with

a pulsed neutron tool.

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* The March 2009 second article of Robert Garotta:

About Gamma ratios and their combinations

The ratio between the compressional to shear velocities
(Gamma or Γ = Vp/Vs) is a key parameter in the
combination of P and S (or PS) data. It can be derived in
several ways. The most obvious are the ratio between the S
to P propagation times between associated events (Γ T) and
the ratio between P to S normal moveout velocities (Γ V).
Comparing P and S (or P and PS) seismic amplitudes also
gives access to Gamma ratio (ΓA).
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*The March 2009 Article: Gene Ballay and the uncertainty concepts in Petrophysics
Risky Business
We all realize that our evaluations can be no better than the data, and model, allow.
At the simplest level we often select Optimistic, Expected and Pessimistic parameter estimates, and bound the result accordingly.
It is, however, relatively simple to address the uncertainty question in a more comprehensive, quantitative fashion, and better identify where to focus time, and money, in search of an improved evaluation.
As carbonate (rather than shaly sand) petrophysicists, our Sw estimates are typically compromised by uncertainty in the Archie equation attributes.

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*Which Depth Imaging Method Should You Use?

  A Roadmap In The Maze of 3D Depth Imaging.

- A Contribute of Biodo Biondi to our discussion -

Today’s explorationist is confronted with a large array of three dimensional depth imaging options, ranging from a variety of Kirchhoff implementations to a variety of waveequation
implementations. Historically, the choice of a depth migration algorithm was simple: Kirchhoff was the only practical option. This has changed. Advances in computing and clever algorithms
have made waveequation migration an economically feasible alternative. With so many choices, making the right choice of imaging method for a given objective can be a daunting task.
We briefly examine the origins of the various imaging methods, describe their relative approximations, and assess their relative merits and applicability.

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*Good News and Bad News -   The January 2009 Newsletter

When observed, mud filtrate invasion likely signals that the formation has at least some amount of permeability. At the simplest level, and assuming a contrast in Rmf & Rw, there may be SP development, which in the presence of potassium feldspars, or uranium, can allow one to identify a reservoir that would not be clear on the GR, and can even offer an estimate of Rw.

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*Testing, Testing 1,2,3  The October Newsletter.  Gene Ballay

Pressure profiles provide important, basic information on reservoir fluids and rock continuity, and in some locales are vital to an accurate interpretation.
· Fluid typing, via determination of the fluid pressure gradient
· Fluid contact placement, via observation of pressure gradient changes, Reservoir continuity, via identification of similar, but offset, pressure gradients.

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* Testing, Testing 1,2,3  The September Newsletter II

    on Formation Pressure Profiles .  Gene Ballay

    DOWNLOAD Part 1

* Determinismus and/or Artificial Intelligence for Pattern Recognition  ?   Hansruedi Frueh

Artificial Intelligence Methods for Pattern Completion and Interpretation, AI Methods for Applications in the field of Geosciences.

An interview with Hansruedi Frueh, instructor for

the course: " The Logic of Neural Networks for the Petrophysical,

Seismic and Facies Estimation ".   DOWNLOAD

* Two for One.  On the August 2008 GeoNeurale Newsletter :

A routine suite of open hole logs, that includes both porosity and resistivity, has the potential to provide not one, but two, independent evaluations of the formation.  DOWNLOAD

*Double Duty on the side of Carbonates.

GeoNeurale issues its first Newsletter: "Double Duty with The

Old and The New".  A communication platform among

Geoscientists on Carbonate Petrophysics. DOWNLOAD

*GeoNeurale presents the widest and most advanced research project ever planned on the Bavarian Malm. The project covers a multidisciplinary integrated program of special seismic, petrophysical and surface measurements and the application of new derived analytical and processing methods focused on the interpretation of the structural and facies attributes to maximize the efficiency of geothermal projects.

*Petrophysics and Geostatistics: New analytical methods

*The Malm Research as a top priority.

*Application of Neural Networks to the Estimation and Classification of petrophysical related properties  for

reservoir analysis.

*Multilayer Perceptrons and NN architectures for the Estimation

and mapping of petrophysical properties.

*Supervised methods training sets from core porosity, GR

for modeling the Porosity log.

*Defining Electrofacies: Supervised and Non-Supervised

Approaches

*From Bivariate to Multivariate Statistics: Electrofacies classification.

*Integration of Petrophysical Analysis with Neural Networks.