SPE HF textbook Flashcards
(19 cards)
The G-function is a dimensionless time function where the ___ is normalized to the _______.
The G-function is a dimensionless time function where the shut-in time is normalized to the pumping time. Nolte (1979) originally conceived of an iterative approach, where various functions are applied to the shut-in time based on the ______ development while pumping
The rate of fracture area development is related to the ______ of the treatment, which is the volume of fracture created at the end of pumping divided by the volume of fluid injected
For most low-permeability systems, the abbreviated G-function approximation is:
As t = tp at shut in, the G-function has a value of _____ at shut in and increases with dimensionless shut-in time.
In the G-function analysis for closure, the same derivative constructions are used, as in the square-root analysis. These are:
On the G-Function analysis plot, closure is found by the departure of the semi-log derivative from the ______ drawn through the origin, as in the square-root-of-time analysis
On the G-Function analysis plot, closure is found by the departure of the _________ from the tangent line drawn through the origin, as in the square-root-of-time analysis
In the examples shown in Figs. 14.15 and 14.16, there is a non-linear derivative early in the shut-in time (G < 2). The more rapid early pressure decay indicates some form of ________ after shut in, and when the fluid pressure in the fracture is high. This is often referred to as a “pressure-dependent leakoff,” or stress-dependent permeability signature, although other causes may exist
In the examples shown in Figs. 14.15 and 14.16, there is a non-linear derivative early in the shut-in time (G < 2). The more rapid early pressure decay indicates some form of accelerated leakoff after shut in, and when the fluid pressure in the fracture is high. This is often referred to as a “_________,” or stress-dependent permeability signature, although other causes may exist
In the examples shown in Figs. 14.15 and 14.16, there is a non-linear derivative early in the shut-in time (G < 2). The more rapid early pressure decay indicates some form of accelerated leakoff after shut in, and when the fluid pressure in the fracture is high. This is often referred to as a “pressure-dependent leakoff,” or ________, although other causes may exist
The end of the non-linear behavior of the semi-log derivative is taken as the end of variable, or accelerated, leakoff, and is an indication of the pressure at which the flow capacity of the formation stabilizes. It is referred to as the “______” pressure (or fissure-closure pressure)
The end of the non-linear behavior of the semi-log derivative is taken as the end of variable, or accelerated, leakoff, and is an indication of the pressure at which the flow capacity of the formation ______. It is referred to as the “fissure opening” pressure (or fissure-closure pressure)
The end of the non-linear behavior of the semi-log derivative is taken as the end of variable, or accelerated, leakoff, and is an indication of the pressure at which the flow capacity of the formation stabilizes. It is referred to as the “fissure opening” pressure (or __________)
The end of the non-linear behavior of the ________ is taken as the end of variable, or accelerated, leakoff, and is an indication of the pressure at which the flow capacity of the formation stabilizes. It is referred to as the “fissure opening” pressure (or fissure-closure pressure)
The end of the non-linear behavior of the semi-log derivative is taken as the end of variable, or accelerated, ______, and is an indication of the pressure at which the flow capacity of the formation stabilizes. It is referred to as the “fissure opening” pressure (or fissure-closure pressure)
In some cases, _____ leakoff may be slower than expected for a single planar, linear elastic fracture that adheres to the PKN geometry assumptions. When this occurs, the semi-log derivative will fall below the straight line through the origin. There are many reasons why the early leakoff rate may be retarded, associated with deviations from the assumptions of the linear-elastic, constant-height PKN model. Some of these are closure of secondary fractures at a stress above the minimum horizontal stress, fracture height recession, and inelastic rock rebound.
In some cases, early leakoff may be slower than expected for a single planar, linear elastic fracture that adheres to the PKN geometry assumptions. When this occurs, the semi-log derivative will fall _____ the straight line through the origin. There are many reasons why the early leakoff rate may be retarded, associated with deviations from the assumptions of the linear-elastic, constant-height PKN model. Some of these are closure of secondary fractures at a stress above the minimum horizontal stress, fracture height recession, and inelastic rock rebound
In some cases, early leakoff may be slower than expected for a single planar, linear elastic fracture that adheres to the PKN geometry assumptions. When this occurs, the semi-log derivative will fall below the straight line through the origin. There are many reasons why the early leakoff rate may be retarded, associated with deviations from the assumptions of the linear-elastic, constant-height PKN model. Some of these are….
