When water is produced, the liquid flow properties are generally taken to be averages of the oil and water properties. If there is no slip between the oil and water phases, the liquid density is the volume fraction-weighted average of the oil and water densities. The volume fraction-weighted averages will be used to estimate liquid… Continue reading Accounting for the Presence of Water
Month: June 2023
Oil Viscosity
Oil viscosity can be estimated with the correlations of Beggs and Robinson (1975) and Vasquez and Beggs (1980). The “dead” oil viscosity is where The oil viscosity at any other pressure below the bubble point is where If the stock tank oil viscosity is known, this value can be used for μod. For pressures above the… Continue reading Oil Viscosity
Property Correlations for Two-Phase Systems
This subsection presents the most widely used property correlations for two-phase oilfield hydrocarbon systems. The downhole volumetric flow rate of oil is related to the surface rate through the formation volume factor, Bo: Here ql is the actual liquid flow rate at some location in the well or reservoir. The downhole gas rate depends on the solution gas–oil… Continue reading Property Correlations for Two-Phase Systems
Properties of Saturated Oil
General Properties of Saturated Oil The bubble-point pressure is the important variable in characterizing saturated oil. At pressures above the bubble point, oil behaves like a liquid; below the bubble point, gas comes out of solution, becoming free gas coexisting with oil. The formation volume factor, Bo, measured in res bbl/STB, for oil above the bubble-point… Continue reading Properties of Saturated Oil
Introduction
The performance relationships presented were for single-phase oil wells and, while gas may come out of solution after oil enters the wellbore, the use of those relationships does not consider free gas to be present in the reservoir. Expansion of oil itself as a means of recovery is a highly inefficient mechanism because of the oil’s… Continue reading Introduction
Summary of Single-Phase Oil Inflow Performance Relationships
The presented three inflow performance equations that can be used to analyze the reservoir behavior for single-phase oil production: steady-state, transient, and pseudosteady-state flows. The production engineer selects the most appropriate of these relationships based on the far-field boundary condition for the well of interest. If the pressure, pe, at the drainage boundary can be approximated… Continue reading Summary of Single-Phase Oil Inflow Performance Relationships
Effects of Water Production, Relative Permeability
Provided volumetric flow rates of undersaturated oil reservoirs as functions of the permeability, k. This permeability was used as a reservoir property. In reality this is only an approximation, since such a use of permeability is correct only if the flowing fluid is also the only saturating fluid. In such case the “absolute” and “effective” permeability values are… Continue reading Effects of Water Production, Relative Permeability
Inflow Performance Relationship
All well deliverability equations relate the well production rate and the driving force in the reservoir, that is, the pressure difference between the initial, outer boundary or average reservoir pressure and the flowing bottomhole pressure. If the bottomhole pressure is given, the production rate can be obtained readily. However, the bottomhole pressure is a function of the… Continue reading Inflow Performance Relationship
Wells Draining Irregular Patterns
Rarely do wells drain regular-shaped drainage areas. Even if they are assigned regular geographic drainage areas, these are distorted after production commences, either because of the presence of natural boundaries or because of lopsided production rates in adjoining wells. The drainage area is then shaped by the assigned production duty of a particular well. To account for irregular drainage… Continue reading Wells Draining Irregular Patterns
Transition to Pseudosteady State from Infinite Acting Behavior
Earlougher (1977) indicated that the time, tpss, at which pseudosteady state begins is given by where A is the drainage area and tDA has a characteristic value that depends on the drainage shape. For a regular shape such as a circle or a square, the dimensionless time at the onset of pseudosteady state, tDApss, is equal to 0.1. For a well… Continue reading Transition to Pseudosteady State from Infinite Acting Behavior