General Field Information |
| Produces Oil: Yes Produces Gas: No |
| Geologic Province: |
Eastern side of the Forest City Basin |
| Exploration Method: |
Subsurface geologic structural mapping and core holes |
| Surface Formation: |
Upper Pennsylvanian, Shawnee Group Oread Limestone |
| Oldest Formation Penetrated: |
Mississippian, Osage |
| Drilling Casing Practices: |
Most operators cement 40 to 60 feet of 7" surface casing and drill a 6 1/4" hole. Fresh water is used for drilling to 1100 feet where chemicals and gel are then added and mud is used to total depth, usually 20 to 50 feet into the Mississippian. Open hole logs are usually run prior to cementing 4 1/2" casing from bottom to surface. Pay zones are perforated with 2 to 4 shots per foot. Most operators "clean up" the perforations with 250 gallons of MCA prior to fracture treating the reservoir with 3 to 8 thousand pounds of sand carried by 100 to 200 barrels of gelled KCI water. |
| Electric Logging Practices: |
Compensated Neutron, Compensated Density and Dual Induction Electric logs are generally run by most operators. |
| Comments: |
Proven Productive Area: In the mid 1980s, these three pools were in their early developmental stages and it was thought that they might eventually coalesce. It appeared likely that the Upper McLouth Sandstone would be productive over 940 acres, the Middle McLouth over 80 acres, and the Lower McLouth over 670 acres. It was thought likely that the total productive area in the three pools would be 1100 acres. At that time a spacing order by the Kansas Corporation Commission set the spacing for oil at 10 acres and spacing for gas at 40 acres.
Other Shows:
Before 1985 shows of tarry oil had been noted in several wells in two intervals that were not yet productive within the pools. They were in a Lower Cherokee Sandstone located 70' above the Upper McLouth Sandstone and in the Lower Cherokee Burgess Sandstone found beneath the McLouth Sandstones and directly overlying the Mississippian. |
| Discussion: |
1985: The three pools are still in the developmental stage and may all eventually coalesce. Developmental drilling around the Leavenworth Pool, discovered by Jennings Drilling Company and first produced in April of 1983, resulted in one other producer and several dry holes that discouraged activity until April and May of 1984 when discovery wells for the Leavenworth Northeast Pool, also found by Jennings Drilling Company, and the Apple Valley Pool, found by Billy Oil Company, were drilled. Drilling activity in the second half of 1984 and to present has been brisk.
The Leavenworth and Leavenworth Northeast Pools were found using surface geologic structural mapping techniques utilizing surface outcrops and shallow core holes. Discovery wells are situated on surface structures having 10 to 20 feet of closure. The surface features appear to be a result of differential compaction over anomalously thick sandstones in the McLouth interval and not deeper seated structures.
Production rates and estimated reserves are substantial considering the shallow depths of the reservoirs, 1200 to 1400 feet deep. Since the three pools are newly discovered and only partially developed, estimated recoveries are speculative. It is estimated the pools will combine to yield 750,000 barrels of oil and 1.6 billion cubic feet of gas from 1100 productive acres. Only 8 to 10% of original oil in place is expected to be recovered by primary recovery methods due to the low gravity, 23 degrees API, and relatively low temperature and pressure due to shallowness of the reservoirs. Also due to the low gravity of the oil, the reservoirs are not likely to be candidates for a conventional water flood but may be suitable for some type of thermal flooding.
The McLouth Sandstones derive their name from the McLouth Gas and Oil Field, which was discovered 1939 and is located 12 miles southwest of the Leavenworth Pool. The McLouth Sandstones are below the Bartlesville Sandstones (Lee, 1944), which are found higher in the Cherokee stratigraphic section.
Each of the three McLouth reservoirs has a different depositional environment. The lenticular sandstones of the Upper McLouth interval are irregularly shaped near shore marine sand bars. Their base is generally flat and they thicken upward. The Lower McLouth Sandstones are related to a channel system, most likely a distributary channel system, but possibly a fluvial channel system. Their geometry suggest the individual sand lenses are point bars. Their top is nearly flat and they thicken in the direction of the channel. Thinning is gradual toward the inside of the arcuate sandstone lenses, but very abrupt on the outside (channel side) of the sand bodies. The sands tend to be developed in channel systems that appear to follow erosional lows on the Mississippian surface found 60 feet below. The Middle McLouth Sandstone is not widespread, being found in only five wells at present. Rocks in the Middle McLouth interval are usually sandy shale found directly on top of the Lower McLouth Sandstone and represent floodplain or levee deposits associated with the Lower McLouth channel system. The sandstone phases of the Middle McLouth are most likely crevasse splay type sandstones. |
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