Category: Enhanced Oil Recovery

It was noted that the microscopic displacement efficiency is largely a function of interfacial forces acting between the oil, rock, and displacing fluid. If the interfacial tension between the trapped oil and displacing fluid could be lowered to 10–2 to 10–3 dynes/cm, the oil droplets could be deformed and squeeze through the pore constrictions. A miscible process…

During the early stages of a waterflood in a water-wet reservoir system, the brine exists as a film around the sand grains, and the oil fills the remaining pore space. At an intermediate time during the flood, the oil saturation has been decreased and exists partly as a continuous phase in some pore channels but…

Tertiary oil recovery refers to the process of producing liquid hydrocarbons by methods other than the conventional use of reservoir energy (primary recovery) and secondary recovery schemes discussed in the last section. In this text, tertiary oil recovery processes will be classified into three categories: (1) miscible flooding processes, (2) chemical flooding processes, and (3)…

Gasflooding was introduced in where the injection of an immiscible gas was discussed in retrograde gas reservoirs. Gas is frequently injected in these types of reservoirs to maintain the pressure at a level above the point at which liquid will begin to condense in the reservoir.10,11 This is done because of the value of the liquid…

Equation (11.1) is an expression for the overall recovery efficiency for any fluid displacement process: where E = overall recovery efficiency Ev = volumetric displacement efficiency Ed = microscopic displacement efficiency The volumetric displacement efficiency is made up of the areal displacement efficiency, Es, and the vertical displacement efficiency, Ei. To estimate the overall recovery efficiency, values for Es, Ei, and Ed must be…

The injection and production wells in a waterflood should be placed to accomplish the following: (1) provide the desired oil productivity and the necessary water injection rate to yield this oil productivity and (2) take advantage of the reservoir characteristics, such as dip, faults, fractures, and permeability trends. In general, two kinds of flooding patterns are…

Several factors lend an oil reservoir to a successful waterflood. They can be generalized in two categories: reservoir characteristics and fluid characteristics. The main reservoir characteristics that affect a waterflood are depth, structure, homogeneity, and petrophysical properties such as porosity, saturation, and average permeability. The depth of the reservoir affects the waterflood in two ways.…

The waterflooding process was discovered quite by accident more than 100 years ago when water from a shallow water-bearing horizon leaked around a packer and entered an oil column in a well. The oil production from the well was curtailed, but production from surrounding wells increased. Over the years, the use of waterflooding grew slowly…

As mentioned in the previous section, there are in general two types of secondary recovery processes—waterflooding and gasflooding. These will both be discussed in this section. Waterflooding has been the most used process, but gasflooding has proven very useful with reservoirs with a gas cap and where the hydrocarbon formation has a significant dip structure…

The initial production of hydrocarbons from an oil-bearing formation is accomplished by the use of natural reservoir energy. As discussed in this type of production is termed primary production. Sources of natural reservoir energy that lead to primary production include the swelling of reservoir fluids, the release of solution gas as the reservoir pressure declines, nearby…