3. Reservoirs and Cap Rocks

This chapter delves into the fundamental aspects of reservoir rocks, which are pivotal in the storage and filtration of fluids, particularly oil and gas. It begins with an overview of reservoir rocks, defining them as rocks with storage spaces capable of holding and filtering fluids. The text emphasizes that over 99% of oil and gas reserves are found in sedimentary rocks, with sandstone and carbonate reservoirs being the primary types. The two critical characteristics of reservoir rocks, porosity and permeability, are explored in detail. Porosity refers to the storage space within the rock, while permeability indicates the rock's ability to allow fluids to flow through it. The chapter also categorizes reservoir rocks based on various criteria, including rock type, storage space, permeability, and the characteristics of oil and gas reservoirs. It discusses the different types of pores, their genesis, and their impact on fluid flow. The text concludes by highlighting the importance of understanding these aspects for effective oil and gas exploration and development.