Secondary migration system

Transfer facilities, processors and rerefiners, and burners must also have secondary containment systems to prevent oil from reaching the environment in the event of a spill or leak. Secondary containment consists of an oil-impervious dike, berm, or retaining wall to contain releases, as well as an oil-impervious floor to prevent migration. 

The secondary hydrocarbon migration system in a basin at a certain moment during its evolution can be characterized by the masses and initial composition of the petroleum hydrocarbons available for secondary migration, the three-dimensional pattern of secondary hydrocarbon migration, i.e. the directions and lengths of the hydrocarbon migration paths, the flux of... 

Hydrostatic secondary hydrocarbon migration systems, in which the dominant forces influencing hydrocarbon migration are the buoyancy forces and the capillary pressure gradients (Section 4.3.3). 

The system of hydrodynamic secondary hydrocarbon migration, whether the hydrocarbons move in separate phase, in very fine suspension or in aqueous solution, is influenced by the porosity and permeability distribution in a sedimentary basin, and the magnitude and direction of the net driving force for groundwater flow. As a consequence, the different processes and associated forces that are responsible for the hydrodynamic conditions in a sedimentary basin also determine to a greater or less extent the characteristics of the hydrocarbon migration system in a hydrodynamic basin (Sections 4.3.4.1, 4.S.4.2 and4.3.4.3). 

The secondary hydrocarbon migration system influences both the distribution and the accumulation of hydrocarbons in a sedimentary basin (Table 6.1). Knowledge of the characteristics of a hydrocarbon migration pattern at a certain time during the basin s evolution, provides information on preferred paths of hydrocarbon migration and may indicate areas favourable or unfavourable for hydrocarbon accumulation during that time. In order to establish the amounts and nature of accumulated hydrocarbons and the exact location of the most favourable positions for hydrocarbon accumulation in a... 

The main types of raw data used in the analysis of secondary hydrocarbon migration systems for basin evaluation are those relating to present and past physico-chemical characteristics of groundwater (groundwater pressures, temperatures, salinities, chemical compositions) and porosities and permeabilities of the subsurface. In addition, information on the physicochemical characteristics of source rocks and of hydrocarbon acciuuulations is necessary to complete the quantitative assessment of hydrocarbon migration systems. 

QUALITATIVE ANALYSIS OF SECONDARY HYDROCARBON MIGRATION SYSTEMS... 

In the qualitative analysis of hydrocarbon migration systems, attention is focussed on the identification of present and past basin-wide or regional patterns of secondary hydrocarbon migration. In a sequence of steps, a set of maps is prepared, which in combination will qualitatively show the potential patterns of secondary hydrocarbon migration at a certain time during the evolution of a sedimentary basin. 

Qualitative analysis of secondary hydrocarbon migration systems... 

A quantitative analysis of present-day secondary hydrocarbon migration for basin evaluation can be restricted to the prospective parts of a sedimentaiy basin as selected on the basis of the previously described qualitative study (Chapter 7). The quantitative assessment of present-day hydrocarbon migration systems is described separately for hydrostatic and hydrodynamic conditions of the prospective parts of the basin (Sections 8.1, 8.2 and 8.3). Section 8.4 briefly describes the available approaches for a quantitative analysis of the evolution of secondary hydrocarbon migration systems. 

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