Page 21 - Fundamentals of Reservoir Engineering

CONTENTS XXI

Fig. 7.22 Numerical simulation model showing the physical no-flow boundary drained by
well A and the superimposed square grid blocks used in the simulation 198

Fig. 7.23 Horner buildup plot, infinite reservoir case 201

Fig. 7.24 Position of the well with respect to its no-flow boundary; exercise 7.7 203

Fig. 7.25 Pressure buildup analysis to determine the average pressure within the no-flow
boundary, and the dynamic grid block pressure (Exercise 7.7) 204

Fig. 7.26 Influence of the shape of the drainage area and degree of well asymmetry on the
Horner buildup plot (Exercise 7.7) 205

Fig. 7.27 Multi-rate oilwell test (a) increasing rate sequence (b) wellbore pressure
response 210

Fig. 7.28 Illustrating the dependence of multi-rate analysis on the shape of the drainage
area and the degree of well asymmetry. (Exercise 7.8) 214

Fig. 7.30 Multi-rate test analysis in a partially depleted reservoir 219

Fig. 7.31 Examples of partial well completion showing; (a) well only partially penetrating
the formation; (b) well producing from only the central portion of the formation; (c)
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well with 5 intervals open to production (After Brons and Marting ) 220
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Fig. 7.32 Pseudo skin factor S b as a function of b and h/r w (After Brons and Marting )
(Reproduced by courtesy of the SPE of the AIME) 220

Fig. 7.33 (a) Amerada pressure gauge; (b) Amerada chart for a typical pressure buildup
survey in a producing well 222

Fig. 7.34 Lowering the Amerada into the hole against the flowing well stream 223

Fig. 7.35 Correction of measured pressures to datum; (a) well position in the reservoir, (b)
well completion design 223

Fig. 7.36 Extreme fluid distributions in the well; (a) with water entry and no rise in the
tubing head pressure, (b) without water entry and with a rise in the THP 224

Fig. 7.37 Pressure buildup plot dominated by afterflow 225

Fig. 7.38 Russell plot for analysing the effects of afterflow 226

Fig. 7.39 (a) Pressure buildup plot on transparent paper for overlay on (b) McKinley type
curves, derived by computer solution of the complex afterflow problem 227
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Fig. 7.40 McKinley type curves for 1 min <∆t < 1000 min. (After McKinley ) (Reproduced
by courtesy of the SPE of the AIME) 228

Fig. 7.41 Buildup plot superimposed on a particular McKinley type curve for T/F = 5000 230

Fig. 7.42 Deviation of observed buildup from a McKinley type curve, indicating the
presence of skin 230