This chapter subdivides the hydrocarbon migration into primary, secondary, and tertiary migrations. These are described as a multiphase fluid flow driven by petroleum fluid potential gradients. The primary migration represents the release of generated hydrocarbon molecules from the kerogen matrix when the sorptive capacity of the matrix is exceeded, often called expulsion by pressure-driven movement through the source rock matrix and transient microfractures. In the case of oil, the secondary and tertiary migrations represent a longer-range flow from source rock to reservoir and remigration from one accumulation to another, respectively. It takes place through a combination of carrier beds, faults, and fractures driven by the balance between fluid potential gradients that are created by buoyancy force, hydraulic gradient, capillary pressure and frictional resistivity force. Description of each force contains mathematical formulations. The secondary migration is described as including separate phase flow, diffusion, solution, and dissolution of gas in oil and water and chemical cracking. The discussion is supported by case studies from the literature.

Chapter 5 explores emerging diasporic communities and their relationships to host societies. Through studies conducted by the sociologist Paul Siu and the historian Wang Gungwu, this chapter explores the ways in which Chinese scholars and writers explored these relationships. The chapter shows that one factor making explorations of these relationships so urgent was the obstacles that Chinese migrants faced in host societies, such as restrictions on immigration and other forms of anti-Chinese legislation. The chapter demonstrates that urgency also stemmed from disruptions to existing diasporic trajectories due to revolution in China and the onset of the Cold War. This chapter then introduces another example of an evolving diasporic community, Los Angeles, focusing in particular on a husband and wife who played prominent roles in shaping the city’s new Chinatown and in asserting the rights of Chinese Americans. The chapter then turns to “return” migration and “secondary” migration in the mid-twentieth century, as ethnic Chinese in Southeast Asia and elsewhere faced anti-Chinese violence and legislation.