Page 9 - Enhanced Oil Recovery in Shale and Tight Reservoirs

viii Contents

11.6 Effect of pressure gradient (injection rate) 326
11.7 Experimental study of forced imbibition 331
11.8 Field tests of surfactant EOR 336

12. Fracturing fluid flow back 339
12.1 Introduction 339
12.2 Field observations and experimental results on flow back 341
12.3 Proposed mechanisms of low flow back 345
12.4 Effect of shut-in time on flow back 359
12.5 Shut-in time effect on fracture conductivity 375
12.6 Effect of initial wettability on flow back 379
12.7 Effect of invasion depth on flow back efficiency and late time oil rate 385
12.8 Effect of surfactants on flow back 390
12.9 Solutions to deal with flow back 395

13. Air injection 401
13.1 Introduction 401
13.2 Laboratory experimental facilities 402
13.3 Kinetic parameters 407
13.4 Oxidation reactions 427
13.5 Spontaneous ignition 435
13.6 Oxygen consumption rate in low-temperature oxidation 452
13.7 Minimum oil content for combustion 453
13.8 Air requirement in combustion 453
13.9 EOR mechanisms and EOR potential in shale and tight reservoirs 454

14. Other enhanced oil recovery methods 457
14.1 Introduction 457
14.2 Sequential method of huff-n-puff CO 2 injection and
surfactant-assisted spontaneous imbibition 457
14.3 Chemical blends 458
14.4 Air foam drive 460
14.5 Branched fractures 461
14.6 Zipper fracture 462
14.7 Refracturing 463
14.8 Diversion technology in fracturing 463
14.9 Energized fluids 464
14.10 Thermal recovery 464
14.11 Microbial EOR 467

Nomenclature 469
References 475
Index 513