6 Flashcards
• THIS HAPPENS WHEN A FLOW
REVERSAL EXIST
• THE CHANGE BETWEEN IMBIBITION
AND DRAINAGE
• OCCURS DUE TO CHANGING
INJECTION PATTERNS, INFILL
DRILLING, AND SHUTTING THE WELL
HYSTERESIS
•DEGREE TO WHICH FLUID
WETS SOLID SURFACE
Wettability
•AN INCREASE IN WETTING-PHASE
•REDUCING SURFACE TENSION
•WATER FLOODING
IMBIBITION PROCESS
•DECREASE IN WETTING-PHASE
•BACK-PRODUCING AN INJECTOR
DRAINAGE PROCESS
•EXIST WHEN DRAINAGE OCCURS AFTER IMBIBITION
SECONDARY DRAINAGE CURVE
HYSTERESIS EFFECT TO SIMULATOR MAY LEAD TO:
•USE OF SMALLER TIME STEPS
• POOR MATERIAL BALANCES
Summing up hysteresis effects with respect to wettability:
• water-wet systems
• oil-wet systems
• intermediate/mixed wettability systems
oil relative permeability may not be affected by water relative permeability since it usually has a negligible effect
water-wet systems
water relative permeability may have a significant effect
oil-wet systems
•EXIST ONLY WHEN DRAINAGE OCCURS FIRST
PRIMARY DRAINAGE CURVE
all bets are off, meaning not one, both or none of the relative permeability curves may be affected
intermediate/mixed wettability systems
SPACING & SMOOTHNESS
•SATURATION-DEPENDENT DATA
•AFFECTS RUNNING TIME OF A MODEL
•SEMILOG PLOT of log (Kr) – Helps to avoid discontinious curve
The shifting of an existing relative permeability curve to account for the varying critical (or connate) water saturations.
END-POINT SCALING
•Weighting of relative permeability
•Is a technique of deciding which relative permeability values to use to determine flow in to a block
MOBILITY WEIGHTING
Another more improved technique is the _____ which reduces gridding effects.
two-point upstream-weighting
A survey on the number of model studies indicated that fewer than 5% of the cells actually required three-phase oil relative permeability.
SATURATION WEIGHTING
VARIATIONS FROM NORM
PSUEDOFUNCTIONS
RELATIVE PERMEABILITIES AND CAPILLARY PRESSURES DETERMINED FROM CROSS-SECTIONAL SIMULATORS
DYNAMIC PSUEDOFUNCTIONS
In order to adjust the water-oil data, use a _____
normalized water saturation
ACCOUNTS FOR THE DEGREE OF SEPARATION OF FLUIDS IN A CELL
VERTICAL EQUILIBRIUM
in the layered reservoir, the average permeability can be calculated using an _____ weighted by net pay
Arithmetic Average Permeability
•“holding variables” for a number of variables which do not change with time.
Transmissibility
We can modify transmissibilities to simulate:
• faults
• shales
•Simulated by increasing the transmissibilities of the well cell. (usually ∆X and ∆Y)
•Simulated by adjusting the skin
factor.
Large Fracture Treatments
