General Field Information |
| Produces Oil: Yes Produces Gas: No |
| Geologic Province: |
Hugoton Embayment |
| Exploration Method: |
Combination Geomorphology, Subsurface Seismic |
| Surface Formation: |
Ogallalla |
| Oldest Formation Penetrated: |
Precambrian |
| Drilling Casing Practices: |
The steps taken in drilling and completing an average well to the Mississippian are as follows:
1) Drill and set 8 5/8" casing through shallow fresh water sands at an average depth of 320'.
2) Drill with native mud from the base of surface casing to the top of the Foraker at around 3400'.
3) Drill to the top of the Mississippian with a mud weight of 9.4 and a water loss of 8.0, testing all good shows on the way down.
4) Run open hole logs.
5) Run 4 1/2" casing to the total depth and cement to surface.
6) Run cement bond and collar correlation log.
7) Perforate zones of interest and test through 2" tubing.
8) Swab and test well spot acid to open perforations.
9) Conduct emulsion tests on oil recovered and treat zones with acid indicated by tests. |
| Electric Logging Practices: |
Schlumberger Logs DIL-SFL, CNL-LDT, EPT, ML, GR. Cyberlook |
| Comments: |
Proven Productive Spacing: 10 acre and 20 acre spacing
Estimated Primary (and Ultimate) Recovery: 782,500 bbls |
| Discussion: |
Anticlinal structural relief is a key element in exploration in this area. Hydrocarbon accumulation is influenced by both paleo and present day structure. There has been vertical structural growth through time, causing paleo structure and present day structure to occur in the same place. This structural growth has been caused by periodic movement of basement blocks. Paleo structure influenced the deposition of porous facies. High energy shoals were deposited over paleobathymetric highs. Mounding also occurred on and around these higher areas. Present day structure provides the trapping mechanism for hydrocarbons, and is also an indicator of paleo structure.
Where well control is sparse and structure cannot be mapped directly, seismic isochron thins are used as an indication of structure. Geomorphic anomalies, in many instances, are also indicative of structure at depth. At Triangle Field seismic lines were laid out over a geomorphic drainage anomaly. An isochron thin was mapped from the seismic, confirming the presence of the structure. |
|
| Geological Age: |
Middle-Upper Pennsylvanian |
| Depositional Environment: |
The Lansing-Kansas City and Marmaton Groups of the Upper and Middle Pennsylvanian were deposited on a shallow epicontinental shelf. Sea level fluctuations caused cyclothems of shallow marine limestones and continental and marine shales to be deposited over a broad area. Each cycle consists of four basic units: 1) a thin transgressive limestone deposited during a rise in sea level, 2) an offshore black shale representing maximum transgression, 3) a regressive limestone deposited during a fall in sea level, and 4) a nearshore shale representing maximum regression. The porous limestone facies are most commonly found within the regressive limestone units. Slow falls in sea level allowed for the growth of algal mound complexes, and for the development of extensive shoals and associated sand sheets. Subaerial exposure and secondary porosity enhancement occurred during periods of maximum regression. |
| Formation Lithology: |
Detailed core analysis indicates that porosity within the limestone units is facies dependent. Hydrocarbons are trapped in porosity associated with algal mound and shoal facies. The principal lithologies associated with the porous mound facies are calcareous algae and encrusting foraminifera rich lime packstones and boundstones. The shoals are (Osagia?) coated lime grainstones and skeletal lime grainstones. Osagia lime grainstones are dominant. |
| Formation Geometry: |
Detailed isopach mapping shows the mounds to be elliptical in shape and anywhere from 40 to 160 acres in size. The shoals are linear bodies that vary from 1/6 to 3/4 of a mile in width and may be several miles long. The "D","I","J", and "L" Zones of the Lansing-Kansas City Group and the Fort Scott Formation of the Marmaton Group are algal mounds with associated shoaling at the top of some of the mounds. The "H" Zone of the Lansing-Kansas City Group and the Pawnee Formation of the Marmaton Group are linear barrier shoals. |
| Trap Type: |
Combination Structural / Stratigraphic |
| Depth Top: |
4428 feet |
| Geological Age: |
Middle-Upper Pennsylvanian |
| Depositional Environment: |
The Lansing-Kansas City and Marmaton Groups of the Upper and Middle Pennsylvanian were deposited on a shallow epicontinental shelf. Sea level fluctuations caused cyclothems of shallow marine limestones and continental and marine shales to be deposited over a broad area. Each cycle consists of four basic units: 1) a thin transgressive limestone deposited during a rise in sea level, 2) an offshore black shale representing maximum transgression, 3) a regressive limestone deposited during a fall in sea level, and 4) a nearshore shale representing maximum regression. The porous limestone facies are most commonly found within the regressive limestone units. Slow falls in sea level allowed for the growth of algal mound complexes, and for the development of extensive shoals and associated sand sheets. Subaerial exposure and secondary porosity enhancement occurred during periods of maximum regression. |
| Formation Lithology: |
Detailed core analysis indicates that porosity within the limestone units is facies dependent. Hydrocarbons are trapped in porosity associated with algal mound and shoal facies. The principal lithologies associated with the porous mound facies are calcareous algae and encrusting foraminifera rich lime packstones and boundstones. The shoals are (Osagia?) coated lime grainstones and skeletal lime grainstones. Osagia lime grainstones are dominant. |
| Formation Geometry: |
Detailed isopach mapping shows the mounds to be elliptical in shape and anywhere from 40 to 160 acres in size. The shoals are linear bodies that vary from 1/6 to 3/4 of a mile in width and may be several miles long. The "D","I","J", and "L" Zones of the Lansing-Kansas City Group and the Fort Scott Formation of the Marmaton Group are algal mounds with associated shoaling at the top of some of the mounds. The "H" Zone of the Lansing-Kansas City Group and the Pawnee Formation of the Marmaton Group are linear barrier shoals. |
| Trap Type: |
Combination Structural / Stratigraphic |
