pressure transient analysis
DESCRIPTION
Mengetahui dan Menghitung Pressure Transient AnalysisTRANSCRIPT
-
Pressure transient testing
-
Three Distinct Production Periods
-
Transient Region. Flow regimes that occur at different flow times for a well
flowing at a constant rate. The flowing bottomhole pressure is shown as a
function of time on both linear and semilog plots. In the transient region, the
reservoir is infinite-acting, and the flowing bottomhole pressure is a linear
function of log t. This region is amenable to analysis by transient methods. and
occurs for radial flow at flow times up to approximately:
where field units are used: t is time in hours, is porosity as a fraction, is
viscosity in cp, C is compressibility in psi-1, re is the external radius in ft, and k is
permeability in md.
Late-Transient Region. At the end of the transient region and prior to the
semisteady-state period, there is a transitional period called the late-transient
region. There are no simple equations that define this region, but the late-
transient period may be very small or practically nonexistent.
Semisteady-State Region. If there is no flow across the drainage boundary and
compressibility is small and constant, a semisteady- or pseudosteadystate
region is observed in which the pressure declines linearly with time. Pressures in
the drainage area decrease by the same amount in a given time, and the
difference between reservoir pressure and wellbore pressure remains constant
during this period. For radial flow, semisteady-state flow conditions
Definitions
-
Curve Shape During a Draw Down Test
-
Semi-logarithmic Plot of Pressure Drawdown Test Data
-
Curve Shape During a Pressure-Buildup Test
-
Horner Plot, Wellbore Pressure Data Plotted for MBH - Analysis
-
MDH (Miller-Dyes-Hutchinson) Plot
-
Downtrending Horner Plots
-
Uptrending Horner Plots
-
Extrapolation of MTR Straight Line
-
Extrapolation of MTR Straight Line
-
Radius of Investigation as a Function of Flow Time During a Pressure-drawdown Test
-
Radius of Investigation as a Function of Flow Time During a Pressure-buildup Test
-
Skin Region
-
Two Region Reservoir Model of Altered Zone Near the Wellbore
-
The rule of thumb is to use
-
Range of applicability of pressure methods at 100 oF
-
Figure 5-10 variation of and z
-
Empirical Deliverability equations (rawlins & schellhardt)
In terms of pressure squared (applicable only at low pressures).
In terms of psudopressure (applicable over all pressure ranges):
-
Fundamental of Pressure Transient Testing in Gas Wells
-
Pressure Transient Test Analysis In Gas Wells
-
Pressure Transient Test Analysis In Gas Wells
-
Pressure Transient Test Analysis In Gas Wells
-
Flow Efficiency (FE), Pressure Drop due to Skin (P)s, Radius of Investigation (ri)
-
The Unit of Calculations
-
Skin Calculation Procedure
In the equation for skin factor during the pressure buildup, Pws is measured just before
shutting in the well, and P1hr is obtained from
the straight-line portion (extrapolated if
necessary) of the buildup curve one hour after
shut-in.
Similarly, the straight-line portion of the drawdown data must be extrapolated to one
hour if the data do not fall on the semilog
straight-line.
-
Constant-Rate Gas Flow Test
-
Discrete-Rate Changes Gas Flow Test (Four Point Deliverability or Backpressure Test)
-
Discrete-Rate Changes Gas Flow Test (Four Point Deliverability or Backpressure Test)
-
Plot:
Where:
Non-Darcy Effects in a Gas Well Test (Four Point Deliverability or Backpressure Test)
-
Example-6.1
-
Example-6.1
-
Solution 6.1
-
Solution 6.1
-
Solution 6.1
-
Cartesian Plot of Multi-Rate Test Data
-
Solution 6.1
-
A strictly constant producing rate is impractical or impossible to maintain.
A more probable mode of operation is production at a constant surface pressure, and if tubing friction effects are negligible, the BHP also is constant.
At early times, however, both BHP & bottom hole rate may be changing rapidly.
Data obtained under these nonideal test conditions can be analyzed accurately with a simple modification of the transient flow equation for constant-rate production.
Variable-Rate Gas Flow Test with Smoothly Changing Rates
-
Surface Production Rate Schedule During Wellbore Storage Period
-
Bottom Hole Flow Rate or Afterflow Following Well Shut-in at the Surface
-
Variable-Rate Gas Flow Test with Smoothly Changing Rates
-
Example-6.2
-
Example-6.2
-
Solution 6.2
-
Solution 6.2
-
Solution 6.2
-
Solution 6.2
-
Solution 6.2
-
Gas Flow Test in Bounded Reservoir
-
Comparison of Dimensionless Pressure Responses for Liquid & Gas Solutions (after Hussainy)
-
Analysis of Gas-Well Buildup Test
-
Buildup Tests with Constant-Rate Production before Shut-In
-
Horners Approximation
Used to avoid the use of superposition in modeling the production history of a variable-
rate well.
-
Horners Approximation
-
Buildup Tests with Constant-Pressure Production Before Shut-In
-
Buildup Tests with Constant-Pressure Production Before Shut-In
-
Determining Average Drainage Area Pressure for Gas Wells
-
Determining Average Drainage Area Pressure for Gas Wells
-
MBH Dimensionless Pressure for Various Well Locations in a Square Drainage Area Locations
-
MBH Dimensionless Pressure for Various Well Locations in a 2:1 Rectangular Drainage Area
-
Example-6.4
-
Solution-6.4(Analysis Using Pressure Variables)
-
Solution-6.4(Analysis Using Pressure Variables)
-
Horner Plot Using Pressure
-
Solution-6.4(Analysis Using Pressure Squared Variables)
-
Solution-6.4(Analysis Using Pressure Squared Variables)
-
Horner Plot Using Pressure Squared
-
Solution-6.4(Analysis Using Adjusted Pressure Variables)
-
Solution-6.4(Analysis Using Adjusted Pressure Variables)
-
Horner Plot Using Adjusted & Adjusted Horner Time Ratio
-
Thank You