Page 286 - Introduction to Petroleum Engineering

274 RESERVOIR PERFORMANCE

Example 14.1 Grid Size
A. A geologic model is built using a grid with 300 cells in the x‐direction and
400 cells in the y‐direction based on seismic areal resolution and 100 cells
in the z‐direction based on well log analysis. How many grid cells are in
the static geologic model?
B. A flow model is upscaled from the geologic model using a grid with 150
cells in the x‐direction, 200 cells in the y‐direction, and 10 cells in the
z‑direction. How many grid cells are in the dynamic flow model?

Answer
A. Number of geologic model cells:
×
×
=
×
NB geo = NXNYNZ = 300 400 ×100 12000000 blocks.
B. Number of dynamic flow model cells:
×
×
=
×
NB flow = NXNYNZ =150 200 ×10 300000 blocks.
Example 14.2 Grid Cell Size
A. Suppose a well is completed in a grid cell with the following properties:
Δx = Δy = 100 ft, net thickness = 16 ft, and porosity = 0.14. What is the pore
volume of the grid cell in reservoir barrels? Note: 1 bbl = 5.6146 cu ft.
B. If the well is producing 100 RB/day of fluid, what percentage of the grid
cell pore volume is being produced in a 5‐day timestep?

Answer
A. Cell pore volume is V =∆ ×∆ ×∆ z ×φ,; therefore
x
y
p net
=
.
3
V =100 ft ×100 ft×16 ft×01422400 ft = 3990 RB
p
B. The amount of fluid produced from the cell is 100RB day× 5days = 500RB
/
which is approximately 12% of cell pore volume produced during the timestep.
14.2 RESERVOIR FLOW MODELINg WORKFLOWS
Different workflows exist for designing, implementing, and executing reservoir pro‑
jects. Modern reservoir flow modeling relies on two types of workflows: green field
workflow and brown field workflow. Green fields include discovered, undeveloped
fields and fields that have been discovered and delineated but are undeveloped.
Brown fields are fields with significant development history. Both workflows are
intended to be systematic procedures for quantifying uncertainty.
The workflow for conducting a probabilistic forecast of green field performance using
a reservoir flow model is shown in Figure 14.2. The workflow begins by gathering data
for the study. Key parameters and associated uncertainties are identified. For example, the
permeability distribution and location of fluid contacts may not be well known. Probability