STANDARD HANDBOOK OF PETROLEUM & NATURAL GAS ...

370 General Engineering and Science
littered with engineered “solutions” to the wrong problem. Such situations emphasize
the need for engineers to assure the correct problem is being solved.
Device Design
A device is a product having all major parts are essentially made by a single
manufacture. Thus, the device design and its manufacturing operation are under the
complete control of the designer. This definition does not dictate a particular product
size or complexity, but does infer that such a product will have limited size and
complexity.
The creation of these device designs is somewhat abstract with regards to providing
products for the “needs of society.” The device designs are in support of an industry
which is vital to society’s operation. Thus, the designer of a device for the petroleum
industry designs, in a sense, for society’s needs. In the petroleum industry, suppliers
of hardware and services for operating companies function more in the area of
designing devices than in the design and supply of systems (or processes) that produce
natural petroleum resources.
System Design
A system design is a product that is made up of a combination of devices and
components. As described above the devices within a system are under the control of
the designer and are designed specifically for the system. Components, on the other
hand, are other devices and/or subsystems which are not made to the specification
of the system designer. Usually these components are manufactured for a number of
applications in various systems. Thus, the system design and the fabrication of the
system are under the control of the system designer. The definition of a system infer
complexity in design and operation.
In the petroleum industry, the term system and process are often considered
synonymous. This is basically because engineering designers in the industry create
“systems” that will carry out needed operational “processes” (e.g., waterflood project).
Role of Models
Once the problem has been defined and the decision has been made to proceed
with a design effort (device or system), the conceptual designs and/or parts of the
device or system are modeled, both mathematically and physically. Engineers design
by creating models that they can visualize, think about, and rearrange until they
believe they have an adequate design concept for practical application. Therefore,
modeling is fundamental to successful engineering design efforts and is used to predict
the operating characteristics of a particular design concept in many operational
situations.
Mathematical Models. In modern engineering practice it is usually possible to develop
mathematical models that will allow engineers to understand the operational
characteristics of a design concept without actually fabricating or testing the device
or system itself. Thus, analysis (using mathematical models) usually allows for great
economic savings during the development of a device or system. To carry out such
analyses, it is necessary to separate a particular design concept into parts-each of
which being tractable to mathematical modeling. Each of these parts can be analyzed
to obtain needed data regarding the operating characteristics of a design concept.
Although repetitive analyses of models are exceedingly powerful design tools, there