Classification of Reservoirs

All hydrocarbon mixtures can be described by a phase diagram such as the one shown in Figure 1-3. Plotted are temperature (x axis) and pressure (y axis). A specific point is the critical point, where the properties of liquid and gas converge. For each temperature less than the critical-point temperature (to the left of Tc in Figure 1-3) there exists a pressure… Continue reading Classification of Reservoirs

Fluid Saturations

Oil and/or gas are never alone in “saturating” the available pore space. Water is always present. Certain rocks are “oil-wet,” implying that oil molecules cling to the rock surface. More frequently, rocks are “water-wet.” Electrostatic forces and surface tension act to create these wettabilities, which may change, usually with detrimental consequences, as a result of… Continue reading Fluid Saturations

Reservoir Height

Often known as “reservoir thickness” or “pay thickness,” the reservoir height describes the thickness of a porous medium in hydraulic communication contained between two layers. These layers are usually considered impermeable. At times the thickness of the hydrocarbon-bearing formation is distinguished from an underlaying water-bearing formation, or aquifer. Often the term “gross height” is employed… Continue reading Reservoir Height

Porosity

All of petroleum engineering deals with the exploitation of fluids residing within porous media. Porosity, simply defined as the ratio of the pore volume, Vp, to the bulk volume, Vb, is an indicator of the amount of fluid in place. Porosity values vary from over 0.3 to less than 0.1. The porosity of the reservoir can be… Continue reading Porosity

Components of the Petroleum Production System

Volume and Phase of Reservoir Hydrocarbons Reservoir The reservoir consists of one or several interconnected geological flow units. While the shape of a well and converging flow have created in the past the notion of radial flow configuration, modern techniques such as 3-D seismic and new logging and well testing measurements allow for a more… Continue reading Components of the Petroleum Production System

Introduction

Petroleum production involves two distinct but intimately connected general systems: the reservoir, which is a porous medium with unique storage and flow characteristics; and the artificial structures, which include the well, bottomhole, and wellhead assemblies, as well as the surface gathering, separation, and storage facilities. Production engineering is that part of petroleum engineering that attempts… Continue reading Introduction

The History Match

The reservoir model developed in the previous two sections will now be applied to history-matching production data from a well in a volumetric, internal gas-drive reservoir. Actual oil production and instantaneous gas-oil ratios for the first 3 years of the life of the well are plotted in Fig. 12.1. The data for the problem were obtained… Continue reading The History Match

History Matching with the Zero-Dimensional Schilthuis Material Balance Equation

Development of the Model The equations do not have a time dimension associated with them. These equations simply relate average reservoir pressure to cumulative production. To obtain rate information, a method is needed whereby time can be related to either the average reservoir pressure or cumulative production. Single-phase flow in porous media was discussed and… Continue reading History Matching with the Zero-Dimensional Schilthuis Material Balance Equation

History Matching with Decline-Curve Analysis

Decline-curve analysis is a fairly straightforward method of predicting the future production of a well, using only the production history of that well. This type of analysis has a long tradition in the oil industry and remains one of the most common tools for forecasting oil and gas production.8–13 In general, there are two approaches to… Continue reading History Matching with Decline-Curve Analysis