Page 7 - Enhanced Oil Recovery in Shale and Tight Reservoirs

vi Contents

4.4 Huff-n-puff versus gas flooding 86
4.5 Core-scale modeling of gas and solvent performance 91
4.6 Reservoir-scale modeling of gas and solvent performance 98
4.7 A field case of methanol injection 101
4.8 Surfactant treatment 102
4.9 Factors that affect huff-n-puff gas injection performance 105
4.10 Optimization of huff-n-puff injection 109
4.11 Mechanisms of huff-n-puff injection 110

5. Optimization of huff-n-puff gas injection in shale and tight
oil reservoirs 117
5.1 Introduction 117
5.2 Setup of a base simulation model 118
5.3 Optimization principles 121
5.4 Optimization criteria 122

6. Gas flooding compared with huff-n-puff gas injection 133
6.1 Introduction 133
6.2 Research results on gas flooding 133
6.3 Gas flooding versus huff-n-puff gas injection 137
6.4 Field applications of gas flooding 145
6.5 Feasibility of gas flooding 149

7. Water injection 151
7.1 Introduction 151
7.2 Waterflooding 151
7.3 Water huff-n-puff injection 156
7.4 Waterflooding versus huff-n-puff water injection 162
7.5 Water injection versus gas injection 162
7.6 Water-alternating-gas (WAG) 166
7.7 Huff-n-puff water and surfactant injection 166
7.8 Water injection in China 167

8. Fluid-rock interactions 173
8.1 Introduction 173
8.2 Evidences of microfractures generated or existing natural
fractures reopened 173
8.3 Effect of confining stress 179
8.4 Effect of bedding 186
8.5 Effect of existing natural fractures 186
8.6 Permeability changes from water-rock interactions 187