Month: June 2023

Fluid property data are extremely important pieces of information used in reservoir engineering calculations. It therefore becomes crucial to be knowledgeable about methods for obtaining these data. It is also important to relate those methods to what is occurring in the reservoir as gas evolves and then separates from the liquid phase. This section contains… Continue reading The Effect of Flash and Differential Gas Liberation Techniques and Surface Separator Operating Conditions on Fluid Properties

The method developed by Havlena-Odeh of applying the general material balance equation was presented.4,5 The Havlena-Odeh method is particularly advantageous for use early in the production life of a reservoir, as it adds constraints that aid in understanding how the reservoir is behaving. This understanding allows for more accurate prediction of production rates, pressure decline, and… Continue reading Material Balance as a Straight Line

The concept of drive indices, first introduced to the reservoir engineering literature by Pirson, was developed.2 To illustrate the use of these drive indices, calculations are performed on the Conroe Field, Texas. Figure 7.1 shows the pressure and production history of the Conroe Field, and Fig. 7.2 gives the gas and two-phase oil formation volume factor for the reservoir fluids. Table… Continue reading The Use of Drive Indices in Material Balance Calculations

The general Schilthuis material balance equation was developed in and is as follows: Equation (3.7) can be rearranged and solved for N, the initial oil in place: If the expansion term due to the compressibilities of the formation and connate water can be neglected, as they usually are in a saturated reservoir, then Eq. (7.1) becomes Example… Continue reading Material Balance in Saturated Reservoirs

These characteristics include primarily (1) pronounced structure, (2) low oil viscosity, (3) high permeability, and (4) low oil velocities. Water drive and hydraulic control are terms used in designating a mechanism that involves the movement of water into the reservoir as gas and oil are produced. Water influx into a reservoir may be edgewater or bottomwater, the latter… Continue reading Good Gravitational Segregation Characteristics

Continuous uniform formations reduce the channeling of the expanding gas cap ahead of the oil and the bypassing of oil in the less permeable portions.

The size of the gas cap is usually expressed relative to the size of the oil zone by the ratio m.

In gas-cap drives, as production proceeds and reservoir pressure declines, the expansion of the gas displaces oil downward toward the wells. This phenomenon is observed in the increase of the gas-oil ratios in successively lower wells. At the same time, by virtue of its expansion, the gas cap retards pressure decline and therefore the liberation… Continue reading Factors Affecting Overall Recovery

The final reservoir type is the saturated oil reservoir and is distinguished by the presence of both liquid and gas in the reservoir. The material balance equations for undersaturated oil reservoirs, apply to volumetric and water-drive reservoirs in which there are no initial gas caps. However, the equations apply to reservoirs in which an artificial… Continue reading Introduction