Changes

==Features==

==Features==

Log analysis packages usually store data in a depth-oriented database. This directly associates a well's scientific data (including wireline traces, core data, tops, and test intervals) with the specific depths of their occurrence. Depending on the LAP used, database depth values may change (1) by a constant increment (usually based on the smallest common sampling increment) or (2) by varying increments (based on each trace's unique sampling nature).

Log analysis packages usually store data in a depth-oriented database. This directly associates a well's scientific data (including wireline traces, [[Overview of routine core analysis|core data]], tops, and test intervals) with the specific depths of their occurrence. Depending on the LAP used, database depth values may change (1) by a constant increment (usually based on the smallest common sampling increment) or (2) by varying increments (based on each trace's unique sampling nature).

To use this data successfully for display and calculations, the user needs to learn the purpose and method of operation for each of the seven basic LAP features. They are

To use this data successfully for display and calculations, the user needs to learn the purpose and method of operation for each of the seven basic LAP features. They are

==Data input==

==Data input==

''Digital data'' are created by writing values into a file in numerical form. Wireline data are now routinely captured on a magnetic medium at predetermined sample increments. Increments vary from tool to tool, from service company to service company (even for comparable tools), and according to the depth recording system (English or metric) used by the service company. The quantity of data values recorded at a given depth increment can also vary. Most logging tools record only one value per increment for each specific trace (slow channel data). Others (for example, a full waveform acoustic tool) acquire multiple values at each depth increment (fast channel data) in order to later replicate and use the entire acquired range of values.

''Digital data'' are created by writing values into a file in numerical form. Wireline data are now routinely captured on a magnetic medium at predetermined sample increments. Increments vary from tool to tool, from service company to service company (even for comparable tools and [http://essaywriting.center essay writing service]), and according to the depth recording system (English or metric) used by the service company. The quantity of data values recorded at a given depth increment can also vary. Most logging tools record only one value per increment for each specific trace (slow channel data). Others (for example, a full waveform acoustic tool) acquire multiple values at each depth increment (fast channel data) in order to later replicate and use the entire acquired range of values.

Each wireline company has its own proprietary format for recording digital data. The two most common formats are LIS (the de facto standard) and BIT. Considerable efforts are being made to standardize all of the various formats into a single industry-wide standard known as the API digital log interchange standard, or DLIS.<ref name=pt08r8>Froman, N. L., 1989, DLIS—API Digital Log Interchange Standard: The Log Analyst, v. 30, n. 5, p. 390–394.</ref>

Each wireline company has its own proprietary format for recording digital data. The two most common formats are LIS (the de facto standard) and BIT. Considerable efforts are being made to standardize all of the various formats into a single industry-wide standard known as the API digital log interchange standard, or DLIS.<ref name=pt08r8>Froman, N. L., 1989, DLIS—API Digital Log Interchange Standard: The Log Analyst, v. 30, n. 5, p. 390–394.</ref>

==Data display==

==Data display==

Data display is the most frequently used LAP feature. Properly displayed data allows users to do the following:

Data display is the most frequently used LAP feature. Properly displayed data allows users to do the following:

* Select consistent parameters for detailed log analysis calculations.

* Select consistent parameters for detailed log analysis calculations.

* Visually correlate all geological, core, wireline, geophysical, and engineering data both within each well and from well to well.

* Visually correlate all geological, core, wireline, geophysical, and engineering data both within each well and from well to well.

Visual examination of a specific formation across a broad area does the following:

Visual examination of a specific formation across a broad area does the following:

===Crossplots===

===Crossplots===

 

[[file:log-analysis-applications_fig5.png|left|thumb|{{figure number|5}}A Pickett plot allow users to interactively draw a line intersecting water wet points (''S''_w = 100%). This line identifies the cementation exponent (''m'') and the product of a × ''R''_''w'' (empirical constant × formation water resistivity) and relates water saturation (''S''_w) to porosity and true resistivity.]]

log-analysis-applications_fig5.png|{{figure number|5}}A Pickett plot allow users to interactively draw a line intersecting water wet points (''S''_w = 100%). This line identifies the cementation exponent (''m'') and the product of a × ''R''_''w'' (empirical constant × formation water resistivity) and relates water saturation (''S''_w) to porosity and true resistivity.

''Crossplots'' (''XPLTs'') relate two or more different trace values to each other at the same depth, such as core [[porosity]] and bulk density. Each type of wireline tool measures a different rock property. By studying the same XPLT in many wells, distinctive data plot patterns related to these rock properties allow users to identify lithologies, porosities, parameters, and other geological and/or engineering relationships.

''Crossplots'' (''XPLTs'') relate two or more different trace values to each other at the same depth, such as core [[porosity]] and bulk density. Each type of wireline tool measures a different rock property. By studying the same XPLT in many wells, distinctive data plot patterns related to these rock properties allow users to identify lithologies, porosities, parameters, and other geological and/or engineering relationships.

Several interactive graphic XPLT techniques and other features have been developed that make crossplots even more useful and powerful:

Several interactive graphic XPLT techniques and other features have been developed that make crossplots even more useful and powerful:

* Three-dimensional plots, allowing rotation of the XPLT around the ''x, y'', and ''z'' axes. This usually requires specialized high performance graphics hardware.

* Three-dimensional plots, allowing rotation of the XPLT around the ''x, y'', and ''z'' axes. This usually requires specialized high performance graphics hardware.

[[file:log-analysis-applications_fig7.png|left|thumb|{{figure number|7}}A two-well histogram allows users to compare data interactively from one well to another by shifting the second well's data across the base well on the screen. A visual best fit is usually satisfactory for determining the amount of normalization required.]]

[[file:log-analysis-applications_fig7.png|300px|thumb|{{figure number|7}}A two-well histogram allows users to compare data interactively from one well to another by shifting the second well's data across the base well on the screen. A visual best fit is usually satisfactory for determining the amount of normalization required.]]

===Histograms===

===Histograms===

===Advanced graphics===

===Advanced graphics===

Most of today's specialized high technology tools have developed specialized graphic displays of both raw and processed data. Understanding both the derivation and the presentation of the data is essential to understanding and interpreting the information presented. Examples include borehole imaging and dipmeter data (see [[Borehole imaging devices]] and [[Dipmeters]]).

Most of today's specialized high technology tools have developed specialized graphic displays of both raw and processed data. Understanding both the derivation and the presentation of the data is essential to understanding and interpreting the information presented. Examples include [[Borehole imaging devices|borehole imaging]] and [[dipmeter]] data.

==Data processing and output==

==Data processing and output==

[[Category:Integrated computer methods]]

[[Category:Integrated computer methods]]

[[Category:Petrophysics and well logs]]

[[Category:Petrophysics and well logs]]