KGS Well Logs Skill

Queries the Kansas Geological Survey (KGS) public well database REST API to locate digitized wireline well logs, retrieve LAS file metadata, and summarize log curve availability for formation evaluation. Also documents access patterns for other state geological survey log repositories.

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No Credential Required

The KGS well database REST API is fully public. No API key needed.

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API Structure

Primary: KGS ORDS Well Services API

Base URL: https://chasm.kgs.ku.edu/ords/rgws.kgs_well_srvc.

The KGS exposes well data through Oracle REST Data Services (ORDS). Endpoints return JSON and follow a consistent pattern.

Get Wells by County

# county_cd is the 3-digit FIPS code for Kansas counties
# Example: 035 = Cowley County, 177 = Shawnee County (Topeka area)
curl -s "https://chasm.kgs.ku.edu/ords/rgws.kgs_well_srvc.get_county_wells_sp?county_cd=035&type=json"

Response fields:

Field	Description
kid	KGS internal well ID (use for follow-up queries)
api_number	14-digit API well number
well_name	Well name as reported
operator	Current operator
county_name	County name
latitude	Decimal degrees (NAD83)
longitude	Decimal degrees (NAD83)
kb_elev	Kelly bushing elevation (ft)
td	Total depth (ft)
spud_date	Spud date

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"

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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.

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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/

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Kansas County FIPS Codes (Common Counties)

For petroleum-relevant counties in Kansas:

County	FIPS	Key Plays
Butler	015	Producing Hugoton, Central KS Uplift
Ellis	051	Smoky Hills, Niobrara
Finney	057	Hugoton gas area
Grant	067	Hugoton
Haskell	081	Hugoton
Reno	155	Central KS
Rush	163	Central KS Uplift
Russell	167	Central KS Uplift
Seward	175	Hugoton

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.

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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.

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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.

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Common Log Curve Mnemonics

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

Mnemonic	Full Name	Unit	PE Application
GR	Gamma Ray	GAPI	Shale volume, lithology discrimination
SP	Spontaneous Potential	MV	Permeability indicator, correlation
ILD	Deep Induction Resistivity	OHMM	Fluid saturation (Sw)
ILM	Medium Induction Resistivity	OHMM	Invasion profile
MSFL	Micro-Spherically Focused Log	OHMM	Flushed zone Rxo
NPHI	Neutron Porosity	V/V or %	Porosity, gas identification
RHOB	Bulk Density	G/CC	Porosity, lithology
DPHI	Density-derived Porosity	V/V	Porosity (from RHOB)
DT	Sonic Transit Time	US/FT	Velocity, compaction, Vp
CALI	Caliper	IN	Borehole diameter, washout
PE	Photoelectric Factor	B/E	Lithology indicator
DEPT	Depth track	FT	Depth reference

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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

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Other State Geological Survey Log Repositories

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

State	Agency	Access Method	URL
Kansas	KGS	REST API (JSON)	chasm.kgs.ku.edu
Oklahoma	OGS	OGS Oil & Gas Portal	https://www.ogs.ou.edu/OGWebNew/
Texas	BEG	Texas Well Finder	https://txwellfinder.beg.utexas.edu/
West Virginia	WVGES	Pipeline data request	https://www.wvgs.wvnet.edu/pipe2/
Colorado	CGS	Well data portal	https://coloradogeologicalsurvey.org/
North Dakota	NDGS	Well completion query	https://www.dmr.nd.gov/oilgas/
Wyoming	WSGS	Oil & Gas portal	https://www.wsgs.wyo.gov/

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.

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Error Handling

Condition	Meaning	Action
ORDS returns Oracle error ORA-XXXX	Invalid parameter or missing required field	Check county_cd is zero-padded 3 digits; verify kid exists
items array empty	No wells with logs in that county	Try adjacent counties; not all KGS wells have digitized logs
LAS URL returns 404	File moved or deleted	Check KGS web interface for alternate access
LAS data parses as all -999.25	Depth range mismatch or corrupt run	Check STRT/STOP/STEP in header; verify null value sentinel
Mnemonics non-standard (e.g., RESM, GRLOG)	Older vintage log with aliased names	Cross-reference with standard aliases in references/api_reference.md
API number format error	KGS uses 14-digit API; NDIC uses 10-digit	Pad with trailing zeros: 10-digit + "0000" = 14-digit

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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.