3-D Reservoir Characterization of the House Creek
         Oil Field, Powder River Basin, Wyoming, V1.00

Table of contents | Glossary | Geology | Depositional model | Heterogeneity | Diagenetic history | Petroleum geology | 1) East-West porosity slices | 2) North-South porosity slices | 3) Onion views of 3-D images | 4) Horizontal slices of porosity | 5) Horizontal and East-West permeability and porosity slices | Technical information 

                                TABLE 1

Names and locations of wells in Campbell County, Wyoming, in which core was sampled for petrographic analysis of the Sussex "B" sandstone, Sussex Sandstone Member of the Upper Cretaceous Cody Shale. Locations are section, township, and range (glossary). An asterisk (*) marks the estimated core depth to the top of the Sussex "B" sandstone; other depths are actual core depths. 



Well Name                           Location,         Top Depth (ft.)

14-9 Federal                   9, T. 42 N., R. 71 W.      7,781

1 Campbell                    21, T. 42 N., R. 71 W.      7,700

1 Govt. Miles "A"              9, T. 44 N., R. 73 W.      8,189

1 Mandel Federal              22, T. 44 N., R. 73 W.      8,166

1-23 House Creek Fed.         23, T. 44 N., R. 73 W.      8,238

1 Empire-Federal "C"          29, T. 45 N., R. 73 W.      8,006

32-1 Marquiss "B"             32, T. 45 N., R. 73 W.      7,980

1  House Creek Fed.           13, T. 45 N., R. 74 W.      8,175

1-11 Red Unit                 26, T. 48 N., R. 79 W.      9,028*

Ucross State                  11, T. 52 N., R. 81 W.      8,233*



                               TABLE 2

Thin-section point-count data for Sussex "B" sandstone facies. Facies definitions use those of Tillman and Martinsen (1985). Data are average volume percentages for number (N) of thin sections listed; Q, quartz grains; PQ, polycrystalline quartz; FSP, feldspar grains; RF, rock fragments; GL, glauconite; MM mudstone matrix; MC, clay matrix; MS, mudstone drapes; SID, siderite drapes; PY, pyrite; CHL, chlorite; QC, quartz cement; CT, chert cement; FSP, feldspar cement; CA, calcite cement; KA, kaolinite booklets; PO, porosity; MCP, minus-cement porosity. Sedimentary facies are listed under column name FACIE for the entire data set (ALL), upper chert-pebble lag sandstone (CTSS), central ridge sandstone (CRSS), high- and low-energy ridge-margin sandstones (HRMS, LRMS), wavy-bedded sandstone (WBSS), and inter-ridge sandstone (IRSS) and siltstone (IRST) (Higley, 1992, 1994). 

FACIE  N     Q   PQ    FSP   RF   GL    MM    MC    MS   SID   PY    CHL    QC   CT    FSP   CA    KA    PO   MCP  
--------------------------------------------------------------------------------------------------------------------
ALL.   54   31   2.9   6.3   13   5.1   3.0   5.9   1.8   0.9   0.6   0.9   7.7   2.1   1.5   11.   0.8   5.4   30
--------------------------------------------------------------------------------------------------------------------
                                                                                            
CTSS   03   27   0.8   3.5   36   3.0   0.0   2.1   0.0   0.0   0.2   0.0   1.9   0.0   0.2   21.   0.0   1.6   25


CRSS  17   32   2.9   5.7   14   4.7   0.7   3.9   2.1   2.9   0.3   0.8   8.5   2.1   1.3   9.5   0.4   7.7   31  


HRMS  08   30   2.7   7.1   11   5.5   2.8   3.8   1.2   0.1   1.3   1.3   8.5   2.2   1.6   14.   0.5   6.1   36


LRMS  03   27   3.1   8.5   12   6.7   1.4   7.6   1.2   0.8   1.0   1.1   11.   1.9   3.8   9.7   0.9   2.4   32


WBSS  06   32   2.1   6.9   10   6.9   3.2   5.1   0.0   0.0   0.4   1.8   7.9   2.2   2.2   12.   1.6   5.9   34


IRSS   10   31   2.8   7.4   11   5.5   3.3   7.2   3.2   0.2   0.7   0.7   8.3   2.2   1.5   8.5   1.3   5.4   29


IRST   07   33   2.3   5.3   10   3.4   10.   13.   3.3   0.2   0.6   0.6   4.5   2.6   0.7   6.8   0.6   2.1   19

Table 3 . Flow-unit characteristics tied to ranges of permeability and porosity, and petrologic (rock) descriptions for Sussex "B" sandstone facies. Flow-unit ratings are from Higley (1994). Lithologic descriptions are based on outcrop studies and examination of core for about 20 wells in the field area, permeability data are based on core analyses of 15 wells within the House Creek field; porosity values are from core and well-logs for about 120 wells in the field area.

FLOW-UNIT RATING, PERMEABILITY (mD), POROSITY (PERCENT), AND PETROLOGIC CHARACTERISTICS 

E,           >15 mD,        10 to 22 percent,

Trough- and planar cross-bedded fine- to medium-grained sandstone that represents the highest depositional energy and greatest reservoir potential. While tabular, wavy-bedded, and ripple-laminated sandstones (flow unit G) near the tops of reservoir sand ridges may exhibit similarly high porosity and permeability values, fluid flow and other factors are different. Thickness of individual E units is as much as 8 ft (2.4 m) but generally less than 2 ft (0.6 m). Sand-ridge intervals composed of mostly E units are up to 25 ft (7.6 m) thick, with an average of about 10 ft (3 m). E units are thickest along field and ridge axes. 

G,        12 to 40 mD,     8 to 18 percent,

Ripple-laminated, tabular, and wavy-bedded fine-grained sandstones that are commonly interbedded with thin trough-cross-bedded fine- to medium-grained sandstones. These are also assigned here to G because they are thin and laterally discontinuous. Thickness of flow-unit G ranges up to about 15 ft (4.5 m) but is generally less than 2 ft (0.6 m). Interbedding of flow units E and G, and to a lesser extent F, results from highly variable depositional energy conditions across the field. 

F,         5 to 20 mD,        8 to 18 percent,

Ripple-laminated, tabular, and wavy-bedded very-fine and fine-grained sandstones. Reservoir favorability is further decreased by the interbedded, thin, calcite-cemented sandstones, numerous mudstone drapes, and biologic reworking. Thickness of F intervals is highly variable, ranging from several feet along and east of field axes, to more than 20 ft (6 m) along the northwestern margin of the field. F units are located mainly near bases of sand ridges and along the western margin of the field. 

P5,      .01 to 2 mD,       1 to 13 percent,

Burrowed and bioturbated mudstone and very-fine-grained sandstones that bound reservoir sandstones. This flow unit contains very low porosity and permeability and forms updip and overlying reservoir seals. 

P6,      .01 to 15 mD,     1 to 16 percent,

Thinly bedded mudstone and calcite-cemented, fine-grained sandstones comprise P6. These form permeability barriers that are laterally continuous and separate upper and lower sand ridges, primarily ridges 1 and 2. P6 thickness is as much as 10 ft (3.5 m), but is generally less than 5 ft (1.5 m). 

P7,       .01 to 19 mD,    1 to 16 percent,

This low-porosity and low-permeability unit is composed of thin mudstones and calcite- and quartz-cemented sandstones. Thickness ranges from inches to less than 5 ft (1.5 m). P7 forms numerous discontinuous permeability baffles.

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