Duration of Event (hr)

Transcription

1 1 Homework 6: Analysis and Interpretation of a Pump Test Sequence Given: READ THIS FIRST! This problem consists of a pressure drawdown/buildup test sequence performed on a pumping WATER well (our campus water well). There are no "tricks" involved this should be a straightforward analysis/interpretation sequence. Be sure to perform all analyses and crosscheck/double-check your work whenever possible. These attached data were taken from a pressure drawdown/buildup test sequence performed on our campus water well. The reservoir interval is a water sand at about 450 ft the well is not stimulated and should not be damaged. The reservoir should be assumed to be homogeneous and infinite-acting. Reservoir properties: φ=0.25 r w =0.36 ft c t =6.5x10-6 psia -1 h=23 ft Water properties: B w =1.0 RB/STB Production parameters: Event µ w =1.0 cp Duration of Event (hr) Pressure at Start of Event (psia) Water Flowrate (STB/D) 1. Drawdown Test p i = Buildup Test 1.82 p wf ( t=0)= Summary Plots: (Drawdown/Buildup Test Sequences)

2 2 Required Results Pressure Drawdown Case Required: Drawdown Case (Analysis of Water Well Test Data (Texas A&M University)) You are to estimate the following: Log-log analysis: a. The wellbore storage coefficient, C s. b. The formation permeability, k. Cartesian analysis of "early" time (wellbore storage distorted) data: a. The pressure at the start of the test, p i. b. The wellbore storage coefficient, C s. Semilog analysis of "middle" time (radial flow) data: a. The formation permeability, k. b. The near well skin factor, s. c. The radius of investigation, r inv, at the end of radial flow. Results: Drawdown Case (Analysis of Water Well Test Data (Texas A&M University)) Log-log Analysis: Wellbore storage coefficient, C s = RB/psia Formation permeability, k = md Cartesian Analysis: Early Time Data Pressure at start of test, p i = psia Wellbore storage coefficient, C s = RB/psia Semilog Analysis: Formation permeability, k = md Near well skin factor, s = Radius of investigation, rinv (end of radial flow) = ft

3 3 Required Results Pressure Buildup Case Required: Buildup Case (Analysis of Water Well Test Data (Texas A&M University)) You are to estimate the following: Log-log analysis: a. The wellbore storage coefficient, C s. b. The formation permeability, k. Cartesian analysis of "early" time (wellbore storage distorted) data: a. The pressure at the start of the test, p wf ( t=0). b. The wellbore storage coefficient, C s. Semilog analysis of "middle" time (radial flow) data: a. The formation permeability, k. b. The near well skin factor, s. c. The radius of investigation, r inv, at the end of radial flow. d. The extrapolated pressure, p*. e. Average reservoir pressure, p (MBH technique if data are available) Cartesian analysis of "late" time (boundary-dominated) data: "Muskat Plot" a. Average reservoir pressure, p. Results: Buildup Case (Analysis of Water Well Test Data (Texas A&M University)) Log-log Analysis: Wellbore storage coefficient, C s = RB/psia Formation permeability, k = md Cartesian Analysis: Early Time Data Pressure at start of test, p wf ( t=0) = psia Wellbore storage coefficient, C s = RB/psia Semilog Analysis: (MDH and Horner analysis) Formation permeability, k = md Near well skin factor, s = Radius of investigation, r inv (end of radial flow) = ft Extrapolated pressure, p* (from Horner analysis) = psia Average reservoir pressure, p (MBH technique) = psia Cartesian Analysis: Late Time Data ("Muskat Plot") Average reservoir pressure, p = psia

4 4 Drawdown Test Data Data Functions: Pressure Drawdown Case Point t (hr) p wf (psia) p p'

5 5 Drawdown Test Data Data Functions: Pressure Drawdown Case (Continued) t p wf p p' Point (hr) (psia)

6 6 Pressure Buildup Test Data Data Functions: Pressure Buildup Case Point t (hr) t e (hr) Horner Time p ws (psia) p p'( t) p'( t e )

7 7 Pressure Buildup Test Data Data Functions: Pressure Buildup Case (Continued) Point t (hr) t e (hr) Horner Time p ws (psia) p p'( t) p'( t e )

8 8 Pressure Buildup Test Data Data Functions: Pressure Buildup Case (Continued) Point t (hr) t e (hr) Horner Time p ws (psia) p p'( t) p'( t e )

9 Log-Log Plot (Pressure Drawdown Case) Log-Log Plot: Pressure Drawdown Case Pressure Drop and Pressure Drop Derivative Data 9

10 Early-Time Cartesian Plot: Pressure Drawdown Case Early-Time Cartesian Plot (Pressure Drawdown Case) 10

11 Semilog Plot: Pressure Drawdown Case Semilog Plot (Pressure Drawdown Case) 11

12 Log-Log Plot (Pressure Buildup Case t Format (No Rate History)) Log-Log Plot: Pressure Buildup Case Pressure Drop and Pressure Drop Derivative Data ( t Format (No Rate History)) 12

13 Log-Log Plot (Pressure Buildup Case t e Format (Includes Rate History)) Log-Log Plot: Pressure Buildup Case Pressure Drop and Pressure Drop Derivative Data ( t e Format (Includes Rate History) 13

14 Early-Time Cartesian Plot: Pressure Buildup Case Early-Time Cartesian Plot (Pressure Buildup Case) 14

15 Semilog Plot: Pressure Buildup Case t Format (No Rate History) Semilog Plot (Pressure Buildup Case t Format (No Rate History)) 15

16 Semilog Plot (Pressure Buildup Case Horner Time Format (Includes Rate History)) Pressure Buildup Case: Horner Time Format (Includes Rate History) 16

17 Late-Time Cartesian Plot ("Muskat Plot"): Pressure Buildup Case Late-Time Cartesian Plot ("Muskat Plot") (Pressure Buildup Case) 17