Category: Saturated Oil Reservoirs

Many studies indicate that the recovery from true solution gas-drive reservoirs by primary depletion is essentially independent of both individual well rates and total or reservoir production rates. Keller, Tracy, and Roe showed that this is true even for reservoirs with severe permeability stratification where the strata are separated by impermeable barriers and are hydraulically… Continue reading Maximum Efficient Rate (MER)

If all gas in reservoirs was methane and all oil was decane and heavier, the PVT properties of the reservoir fluids would be quite simple because the quantities of oil and gas obtained from a mixture of the two would be almost independent of the temperatures, the pressures, and the type of the gas liberation… Continue reading Volatile Oil Reservoirs

The data in Tables 7.3 and 7.4 can be combined to yield values for the oil formation volume factor and the solution gas-oil ratio. The formation volume factor is calculated from Eq. (7.6) or (7.7), depending on whether the pressure is above or below the bubble-point pressure: For p > bubble-point pressure, For p < bubble-point pressure, where REV = Relative volume from the… Continue reading The Calculation of Formation Volume Factor and Solution Gas-Oil Ratio from Differential Vaporization and Separator Tests

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.