1/30/03: Areal Operations


Plan for today:

Depth Conversion of Time Structures.

Measure prospect size.

Generate final structure and interval maps.

Attribute Analysis.

Break

3D Views.


First Session


Generate Velocity Grids, Depth Maps, and Measure Acreage:

Choose Interval Velocities over Average Velocities: PDW Interpretation > Settings >

Depth Conversion, Velocity Type: +Interval Velocity. (OK).

PDW Horizons. Set all Usage options to Time Mapping except for Datum, Wab Group, and Fort

Vermilion which should be set to Depth Conversion. Close Window.


Bring Map View to front. Select Wab horizon. In Map View toolbar, (Show velocity surface).

PDW Interpretation >Grid Velocities.

In Map View toolbar, (Show depth surface).

PDW Interpretation >Convert to Depth.

You can erase depths and erase velocities under PDW Interpretation and reinterpret time if

desired.


Select Fort Vermilion horizon. In Map View toolbar, (Show velocity surface).

PDW Interpretation >Grid Velocities. What are we looking at?

In Map View toolbar, (Show depth surface).

PDW Interpretation >Convert to Depth.


Below colorbar, (Settings), Rotate: and drag mouse to change colors, (OK). Continue to adjust

and use sharp contrast between black and white to define structure fill point. (OK).


Calculate acreage of northern structure around Well 00-03. In the second toolbar of the Map View

window, (Planimeter mode) [a grey oval with a P]. Click around the perimeter representing

structural closure, double-click to close. Acreage appears in Planimeter Tool window.

(Close).


To reset colors: (Settings), (Reset Colors), (OK).


Adjust Min and Max depth values. Note values are greyed out above and below colorbar.

(Settings), Data range mode: *User defined, (OK). Now you can enter new Min and Max

values and (Apply).

Return (Settings) to Data range mode: *Data range before looking at another map.


We started with initial velocity information, usually from well checkshot survey or seismic stacking velocities. We had 2 data points in a velocity survey. Subsequently, we refined this to 5-8 data points, which tied all sonic logs and synthetics to the seismic reflectors. The velocity gradients in the Moosehead seem to be well-behaved, most seismic surveys require layer by layer velocity determination with some layers requiring velocity gradients across the survey. Accurate time to depth conversion is very difficult. Consider yourself lucky if you can predict well tops within 2% of actual depth. That may sound reasonably good, but it is still 200 feet in a 10,000 foot well. Drillers hate that kind of error, especially when you are anticipating a core point or an overpressured zone which could cause a blowout.


Time Structure Contour Map:

PDW File > New Quick Map… , +Moosehead 3D, (OK).


> Main >+Contour Line, *Show color bar, *Show north arrow, *Show title box, *Show scale

bar, *Show map projection info.

> Surface Data

(Main Surface…) > Data Type: +Horizon Time, Time Units: +Milliseconds, Horizon

Name: +Wab Group, (OK).

> Contours

*Automatic contour interval OFF, -> 2 in Contour Interval.

> Size

In Map Scale, *Automatic to OFF, -> 300 in Scale.

> Title

Site or Survey Name: -> “GEO 5220”.

Organization Name: -> YourName.

> Culture

(Load…), (Browse…), Find C:\Documents and Settings\All Users\Application Data\

GeoGraphix\SampleFiles\Moosehead\Culture. +TRGRID.ASC, (Open), (Load).

> Faults

(Import…), +WAB GRP in Import Polygons for Horizon:, (OK), (OK), (Fill Color…),

+Black.

> Wells

(Import Wells from Interpretation), (OK), +Operator name in Line 1:, +Well number in

Line 2:, Text Color: +Black.

(Close).


PDW Quick Map > Zoom Quick Map… -> 150, (OK). Stretch map window.

PDW Quick Map > Adjust Quick Map…, Experiment with parameters later, especially in >Main >

Map Surfaces.


Adjusting the contour curvature is done by smoothing the horizon in PDW Quick Map > Adjust

Quick Map… > Surface Data Processing (Main Surface..), *Apply smoother,

(OK), (Close).


To save a map: PDW File >Save As…, browse for C:\Documents and Settings\All Users\

Application Data\GeoGraphix\Projects\YourName. Rename MAP1 if desired, (Save).


Isochron Contour Map:

PDW File > New Quick Map… , +Moosehead 3D, (OK).


> Main >+Contour Line & Color Density, *Show color bar, *Show north arrow, *Show

title box, *Show scale bar, *Show map projection info.

> Surface Data

(Main Surface…) > Data Type: +Horizon Isochron, Top Horizon Name: +Wab Group,

Bottom Horizon Name: +Fort Vermilion, (OK).

> Contours

*Automatic contour interval OFF, -> 2 in Contour Interval.

> Size

In Map Scale, *Automatic to OFF, -> 300 in Scale.

> Title

Site or Survey Name: -> “GEO 5220”.

Organization Name: -> YourName.

> Culture

(Load…), (Browse…), Find C:\Documents and Settings\All Users\Application Data\

GeoGraphix\SampleFiles\Moosehead\Culture. +TRGRID.ASC, (Open), (Load).

> Faults

(Import…), Import Polygons for Horizon: +Wab Group, (OK), (OK), (Fill Color…),

+Black.


> Wells

(Import Wells from Interpretation), (OK), +Operator name in Line 1:, +Well number in

Line 2:, (Close).


PDW Quick Map > Zoom Quick Map… -> 150, (OK).


To save a map: PDW File >Save As…, browse for C:\Documents and Settings\All Users\

Application Data\GeoGraphix\Projects\YourName. Rename MAP2 if desired, (Save).


Note the thinning in time at the well locations. This indicates a paleo high where the wells were drilled. If the wells were discoveries, this might support drilling additional locations in the southwest corner of the 3D and development locations near wells #1 and #2.

As one would expect, the fault graben in the WAB Group distorts the isochron map.


Depth Contour Map:

PDW File > New Quick Map… , +Moosehead 3D, (OK).


> Main >+Contour Density, *Show color bar, *Show north arrow, *Show title box, *Show

scale bar, *Show map projection info.

> Surface Data

(Main Surface…) > Data Type: +Horizon Depth, Horizon Name: +Wab Group, (OK).

> Contours

*Automatic contour interval OFF, -> 2 in Contour Interval.

> Size

In Map Scale, *Automatic to OFF, -> 100 in Scale.

> Title

Site or Survey Name: -> “GEO 5220”.

Organization Name: -> YourName.

> Culture

(Load…), (Browse…), Find C:\Documents and Settings\All Users\Application Data\

GeoGraphix\SampleFiles\Moosehead\Culture. +TRGRID.ASC, (Open), (Load).

> Faults

(Import…), +WAB GRP in Import Polygons for Horizon:, (OK), (OK), (Fill Color…),

+Black.

> Wells

(Import Wells from Interpretation), (OK), +Operator name in Line 1:, +Well number in

Line 2:, Text Color: +Black.

(Close).

Isopach Contour Map:

PDW File > New Quick Map… , +Moosehead 3D, (OK).


> Main >+Contour Line & Color Fill, *Show color bar, *Show north arrow, *Show title box,

*Show scale bar, *Show map projection info.

> Surface Data

(Main Surface…) > Data Type: +Horizon Isopach, Top Horizon Name: +Wab Group,

Bottom Horizon Name: +Fort Vermilion, (OK).

> Contours

*Automatic contour interval OFF, -> 2 in Contour Interval.

> Size

In Map Scale, *Automatic to OFF, -> 100 in Scale.

> Title

Site or Survey Name: -> “GEO 5220”.

Organization Name: -> YourName.

> Culture

(Load…), (Browse…), Find C:\Documents and Settings\All Users\Application Data\

GeoGraphix\SampleFiles\Moosehead\Culture. +TRGRID.ASC, (Open), (Load).

> Faults

(Import…), Import Polygons for Horizon: +Wab Group, (OK), (OK), (Fill Color…),

+Black.


> Wells

(Import Wells from Interpretation), (OK), +Operator name in Line 1:, +Well number in

Line 2:, (Close).



Attribute Analysis and Mapping

Recommendation for Attribute Analysis: There are some attributes which are logically predictable such as a gas sand producing a bright spot apparent on an amplitude attribute map, or a high frequency response of 2 formations close to each other resulting in a high frequency doublet instead of a lower frequency single reflector when only 1 formation is present.

In general, because of the great number of attribute computations available and the uncertainty of how each is computed, it is usually most productive to generate all attributes and focus on explaining those which support your interpretation.



PDW Tools >Surface Calculator. Study Attribute options. You can find an explanation of each

attribute by moving the mouse to that attribute then RightClick. (Attribute Details). (Close).


Shotgun Approach: Calculate everything and ask questions later. (Select All) under Attributes,

unselect ISOCHRON, *Window About Horizon, Data Type *3D, Output File

Prefix ->FtVerm, Window Definition Horizon 1: +Fort Vermilion, Length [ms] ->50.

(Calculate).

(OK). (Close).


In the Map View window, open 3D Surfaces on the left-hand side. Here are all your attribute

surfaces. Double-click on each to open it. See if any support the decision to drill these

locations.


To delete an attribute surface, RightClick on its name, (Remove File). This should work but

doesn’t on my computer. You can remove by going directly to folder C:\Documents and

Settings\All Users\Application Data\GeoGraphix\Projects\YourName\InterpretationName\

Surfaces and deleting them there.


Return to interpreted horizons by closing 3D Surfaces on the left-hand side of the Map View

window and opening Horizons >FormationName >Time


Try attributes on other horizons during Interpretation Break. Attribute maps can be printed in

Quick Map by specifying attribute in PDW File >New Quick Map… >Surface Data >

Select Attribute Surface.



Interpretation Break: 40 Minutes

Experiment with Making Time, Depth, Isochron, and Isopach Maps.

Experiment with Seismic Attributes.



Second Session


In the Faults window, select the first fault “?”.


PDW Tools >3D View. Stretch window. Note location of 3 wells in right window, and compass

in left window. In the 3D Viewer toolbar, (Rotate). Click and drag on the well locations.

Circles are surface locations. Note changing perspective and moving compass.


In the Faults window, now select Fault1. Note fault plane and continue rotating.

In the 3D Viewer toolbar, (Zoom). Drag downward on window to zoom.

(Pan) to center faults and wells. Bold lines on fault plane are your fault interpretations, fill

between is the computer’s interpolation.

(Plan View) to look from above. (Move Light) to see illumination source. Grab the light and

move to change illumination direction.

(Zoom) and center the fault again.


PDW Display >Properties… Scroll to Horizons, and select Wab Group and Fort Vermilion.

(OK).

Now (Rotate) and examine Horizon/Fault interaction.


Move mouse to Wab horizon, RightClick >Translucent Slider. Slide to adjust transparency. Also

works with faults.


Return to basemap and open Line LBT-201 and 3D E-W Line 75. Return to 3D Viewer.

PDW Display >Properties… Scroll to Seismic Views. Turn off all Seismic Views. Turn

on Lbt-201. (OK). Return to the 3D Viewer, and (Toggle Seismic Display) to add seismic

sections.


You can also paint the horizons with structure colors and seismic attributes previously calculated. PDW Display >Properties… Scroll to Horizons. Highlight Wab Group, Translucence ->9,

Surface Overlay +Time. (Apply).

Highlight Fort Vermilion, Translucence ->10, Surface Overlay +Attribute Surface,

testRMS.svs. (OK).


Now Rotate. Interpretation time to play. Remember to scroll through seismic and watch 3D View.



Interpretation Break: Until End of Class

Experiment with 3D View




Homework Due 2/6/2003 at Beginning of Class:

Generate and print a Time Structure contour map and a Depth contour map for the Fort Vermilion Formation. Generate and print an Isochron map and an Isopach map for the WAB Group to Fort Vermilion interval. Black and white maps OK.


Generate and print [can be black and white] a single 3D view which contains one 3D line, one 2D line, two horizons with Time Surface Overlays, one timeslice, one fault plane, and all three wells.


Reading Assignment for 2/6/2003:

A 3-D seismic case history evaluating fluvially deposited thin-bed reservoirs in a gas-producing property, Geophysics, Vol. 59, No. 11 (November 1994); p. 1650-1665.

A .pdf file of this article can be found at http://utam.gg.utah.edu/gg5220/geo5911r1650.pdf


Class Final Project Begins 2/6/2003. Everyone Be Sure To Show Up.



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