Month: June 2023

Oil is produced from volumetric, undersaturated reservoirs by expansion of the reservoir fluids. Down to the bubble-point pressure, the production is caused by liquid (oil and connate water) expansion and rock compressibility. Below the bubble point, the expansion of the connate water and the rock compressibility are negligible, and as the oil phase contracts owing… Continue reading Oil Recovery by Internal Gas Drive

The method discussed in the previous section also applies to the displacement of oil by gas drive. The treatment of oil displacement by gas in this section considers only gravity drainage along dip. Richardson and Blackwell showed that in some cases there can be a significant vertical component of drainage.9 Due to the high oil-gas… Continue reading The Displacement of Oil by Gas, with and without Gravitational Segregation

The Buckley-Leverett Displacement Mechanism Oil is displaced from a rock by water similar to how fluid is displaced from a cylinder by a leaky piston. Buckley and Leverett developed a theory of displacement based on the relative permeability concept.8 Their theory is presented here. Consider a linear bed containing oil and water (Fig. 10.7). Let the… Continue reading Immiscible Displacement Processes

The following factors affect the macroscopic displacement efficiency: heterogeneities and anisotropy, mobility of the displacing fluids compared with the mobility of the displaced fluids, the physical arrangement of injection and production wells, and the type of rock matrix in which the oil or gas exists. Heterogeneities and anisotropy of a hydrocarbon-bearing formation have a significant… Continue reading Macroscopic Displacement Efficiency

Except for gases at low pressures, the permeability of a rock is a property of the rock and not of the fluid that flows through it, provided that the fluid saturates 100% of the pore space of the rock. This permeability at 100% saturation of a single fluid is called the absolute permeability of the rock. If… Continue reading Relative Permeability

The microscopic displacement efficiency is affected by the following factors: interfacial and surface tension forces, wettability, capillary pressure, and relative permeability. When a drop of one immiscible fluid is immersed in another fluid and comes to rest on a solid surface, the surface area of the drop will take a minimum value owing to the… Continue reading Microscopic Displacement Efficiency

The overall recovery efficiency E of any fluid displacement process is given by the product of the macroscopic, or volumetric displacement, efficiency, Ev, and the microscopic displacement efficiency, Ed: The macroscopic displacement efficiency is a measure of how well the displacing fluid has contacted the oil-bearing parts of the reservoir. The microscopic displacement efficiency is a measure of how well the displacing fluid… Continue reading Recovery Efficiency

The includes a discussion of the fundamental concepts that influence the displacement of oil and gas both by internal displacement processes and by external flooding processes. It is meant to be an introduction to these topics and not an exhaustive treatise. The reader, if interested, is referred to other works that cover the material.1–5 The reservoir… Continue reading Introduction