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 to maximize production (or injection) in a cost-effective manner. In the 15 years that separated the first and second editions of this textbook worldwide production enhancement, headed by hydraulic fracturing, has increased tenfold in constant dollars, becoming the second largest budget item of the industry, right behind drilling. Complex well architecture, far more elaborate than vertical or single horizontal wells, has also evolved considerably since the first edition and has emerged as a critical tool in reservoir exploitation.

In practice one or more wells may be involved, but in distinguishing production engineering from, for example, reservoir engineering, the focus is often on specific wells and with a short-time intention, emphasizing production or injection optimization. In contrast, reservoir engineering takes a much longer view and is concerned primarily with recovery. As such, there may be occasional conflict in the industry, especially when international petroleum companies, whose focus is accelerating and maximizing production, have to work with national oil companies, whose main concerns are to manage reserves and long-term exploitation strategies.

Production engineering technologies and methods of application are related directly and interdependently with other major areas of petroleum engineering, such as formation evaluation, drilling, and reservoir engineering. Some of the most important connections are summarized below.

Modern formation evaluation provides a composite reservoir description through three-dimensional (3-D) seismic, interwell log correlation and well testing. Such description leads to the identification of geological flow units, each with specific characteristics. Connected flow units form a reservoir.

Drilling creates the all-important well, and with the advent of directional drilling technology it is possible to envision many controllable well configurations, including very long horizontal sections and multilateral, multilevel, and multibranched wells, targeting individual flow units. The drilling of these wells is never left to chance but, instead, is guided by very sophisticated measurements while drilling (MWD) and logging while drilling (LWD). Control of drilling-induced, near-wellbore damage is critical, especially in long horizontal wells.

Reservoir engineering in its widest sense overlaps production engineering to a degree. The distinction is frequently blurred both in the context of study (single well versus multiple well) and in the time duration of interest (long term versus short term). Single-well performance, undeniably the object of production engineering, may serve as a boundary condition in a fieldwide, long-term reservoir engineering study. Conversely, findings from the material balance calculations or reservoir simulation further define and refine the forecasts of well performance and allow for more appropriate production engineering decisions.

In developing a petroleum production engineering thinking process, it is first necessary to understand important parameters that control the performance and the character of the system. Below, several definitions are presented.