KGS Well Logs Skill

Response fields:

Get Log Availability for a Well

# kid = KGS well ID from county wells query
curl -s "https://chasm.kgs.ku.edu/ords/rgws.kgs_well_srvc.get_well_log_sp?kid=1050066180&type=json"

Response includes log runs with available curve mnemonics, depth ranges, and LAS file download URLs.

Search Wells by API Number

# Full 14-digit API number
curl -s "https://chasm.kgs.ku.edu/ords/rgws.kgs_well_srvc.get_well_by_api_sp?api_number=15035012340000&type=json"

Get Well Log Details by Log ID

curl -s "https://chasm.kgs.ku.edu/ords/rgws.kgs_well_srvc.get_log_details_sp?log_id=LOG_ID&type=json"

LAS File Download

LAS files (Log ASCII Standard) are the standard digital format for wireline log data. The KGS serves LAS 2.0 files directly via HTTP.

# Download LAS file (URL from get_well_log_sp response)
curl -s "https://www.kgs.ku.edu/WellLogs/logs/LAS/NNNNNN.las" -o well.las

# View first 50 lines to inspect header
head -50 well.las

LAS 2.0 file structure:

~VERSION INFORMATION
 VERS.   2.0    : CWLS LOG ASCII STANDARD - VERSION 2.0
 WRAP.   NO     : ONE LINE PER DEPTH STEP
~WELL INFORMATION
 STRT.FT    1000.0000 : START DEPTH
 STOP.FT    5432.0000 : STOP DEPTH
 STEP.FT       0.5000 : STEP
 NULL.         -999.25: NULL VALUE
 WELL.   SMITH #1     : WELL NAME
 API .   15035012340000 : API NUMBER
 LAT .   37.8234      : LATITUDE
 LONG.  -98.1123      : LONGITUDE
~CURVE INFORMATION
 DEPT.FT           : 1  DEPTH
 GR  .GAPI         : 2  GAMMA RAY
 ILD .OHMM         : 3  DEEP INDUCTION RESISTIVITY
 NPHI.V/V          : 4  NEUTRON POROSITY
 RHOB.G/C3         : 5  BULK DENSITY
~DATA
 1000.0000  42.3  18.4  0.21  2.38
 1000.5000  45.1  17.9  0.22  2.36

Null value: -999.25 is the universal LAS null sentinel. Exclude from statistics and analysis.

KGS Web Interface (Non-API Reference)

For users who prefer a browser workflow:

• Well log search: https://www.kgs.ku.edu/Magellan/well_logs/index.html
• Individual well lookup by API: https://www.kgs.ku.edu/Magellan/Cgi-bin/servedata.cgi
• Stratigraphic picks DB: https://www.kgs.ku.edu/PRS/Strat/

Kansas County FIPS Codes (Common Counties)

For petroleum-relevant counties in Kansas:

Use curl -s "https://chasm.kgs.ku.edu/ords/rgws.kgs_well_srvc.get_county_list_sp?type=json" to get the full county list if the endpoint is available.

Workflow

Step 1 — Resolve Intent

• User provides county name → look up FIPS code → use get_county_wells_sp
• User provides API number → use get_well_by_api_sp
• User provides KGS well ID → go directly to get_well_log_sp
• User wants logs for a formation → search by county, then filter by TD range

Step 2 — Find the Well

# Example: find wells in Russell County (FIPS 167)
curl -s "https://chasm.kgs.ku.edu/ords/rgws.kgs_well_srvc.get_county_wells_sp?county_cd=167&type=json" \
  | jq '.items[] | {kid: .kid, api: .api_number, name: .well_name, td: .td, lat: .latitude, lon: .longitude}'

If the county query returns many wells (>100), add filters or ask the user to specify a smaller area or a well name.

Step 3 — Check Log Availability

# For a specific KGS well ID
curl -s "https://chasm.kgs.ku.edu/ords/rgws.kgs_well_srvc.get_well_log_sp?kid=KID_HERE&type=json" \
  | jq '.items[] | {log_id: .log_id, curves: .curves, depth_from: .depth_from, depth_to: .depth_to}'

Extract the list of curves available (comma-separated mnemonic string) and the LAS download URL.

Step 4 — Download or Describe LAS

If the user wants to analyze curves, download the LAS file and parse the ~CURVE section to list available logs, then the ~DATA section for statistics.

curl -s "LAS_URL_FROM_RESPONSE" -o /tmp/well.las
# Show curve inventory
awk '/^~C/,/^~/' /tmp/well.las | head -30

Step 5 — Produce Output

Summarize the curve inventory table and provide download link. If the user wants formation evaluation, use the curve summary to guide interpretation.

Output Format

Log Availability Query Output

## Well Log Summary — [Well Name], [API Number]

**Well Info:**
- Operator: [Operator]
- County: [County], KS
- TD: [depth] ft
- Spud Date: [date]
- Coordinates: [lat], [lon]

### Available Log Runs

| Run | Curves | Top (ft) | Base (ft) | LAS Download |
|-----|--------|----------|-----------|--------------|
| 1   | GR, ILD, NPHI, RHOB, CALI | 500 | 4,200 | [link] |
| 2   | GR, SP, ILD | 200 | 1,100 | [link] |

### Curve Detail (Run 1)

| Mnemonic | Log Type | Unit | Min Value | Max Value | Null Count |
|----------|----------|------|-----------|-----------|------------|
| GR | Gamma Ray | GAPI | 12.3 | 148.7 | 0 |
| ILD | Deep Induction Res | OHMM | 0.8 | 4,250 | 3 |
| NPHI | Neutron Porosity | V/V | 0.03 | 0.42 | 0 |
| RHOB | Bulk Density | G/C3 | 2.10 | 2.71 | 12 |

**Assessment:** Run 1 provides a full suite for formation evaluation including
porosity (NPHI, RHOB) and saturation (ILD). Suitable for neutron-density
crossplot analysis. [n] null values in RHOB suggest minor washout intervals.

Common Log Curve Mnemonics

See references/api_reference.md for the comprehensive mnemonic table. Frequently used curves:

Porosity Calculations from Log Data

# Density porosity (limestone matrix)
DPHI = (RHOma - RHOB) / (RHOma - RHOfl)
  where RHOma = 2.71 g/cc (limestone), RHOfl = 1.00 g/cc (freshwater)

# Neutron-density crossplot porosity (gas correction)
PHIxp = sqrt((DPHI^2 + NPHI^2) / 2)

# Shale volume from gamma ray (linear)
IGR = (GR - GRmin) / (GRmax - GRmin)
Vsh = IGR  (linear; Clavier: Vsh = 1.7 - sqrt(3.38 - (IGR + 0.7)^2))

# Water saturation (Archie)
Sw = sqrt((a * Rw) / (PHI^m * Rt))
  typical: a=1, m=2, n=2 for clean sandstone

Other State Geological Survey Log Repositories

The KGS has the most accessible API. Other states with digital log access:

For WV well logs specifically: WVGES has digitized logs for some wells but does not expose a public REST API. Requests go through the Pipeline web interface at https://www.wvgs.wvnet.edu/pipe2/ or direct contact.

Error Handling

Caveats and Data Limitations

• Coverage: KGS has digitized roughly 60,000–80,000 logs out of ~100,000+ drilled Kansas wells. Pre-1970 wells often lack digitized logs; paper logs may exist in the KGS core library.
• Vintage logs: Pre-1980 logs used older tool generations. Gamma ray calibration (GAPI) was not standardized until 1978. Compare same-formation values cautiously across vintages.
• Null value -999.25: This is the LAS standard null. Always filter before statistics. Some older files use 0 or 9999 as nulls — check the NULL. line in the header.
• Curve mnemonic aliases: Resistivity logs especially have dozens of mnemonics (ILD, RT, RESD, RDEP, RD, etc.) for the same physical measurement. The references/api_reference.md lists common aliases.
• WV log access: WVGES digitized logs are not on a public API. For Marcellus or Utica formation evaluation in WV, check commercial databases (IHS, Enverus) or request data directly from WVGES.