Computer-based

Reservoir simulation is a technique in which a computer-based mathematical representation of the reservoir is constructed and then used to predict its dynamic behaviour. The reservoir is gridded up into a number of grid blocks. The reservoir rock properties (porosity, saturation, and permeability), and the fluid properties (viscosity and the PVT properties) are specified for each grid block. 

Monitoring and control of the production process will be performed by a combination of instrumentation and control equipment plus manual involvement. The level of sophistication of the systems can vary considerably. For example, monitoring well performance can be done in a simple fashion by sending a man to write down and report the tubing head pressures of producing wells on a daily basis, or at the other extreme by using computer assisted operations (CAO) which uses a remote computer-based system to control production on a well by well basis with no physical presence at the wellhead. 

The reservoir model will usually be a computer based simulation model, such as the 3D model described in Section 8. As production continues, the monitoring programme generates a data base containing information on the performance of the field. The reservoir model is used to check whether the initial assumptions and description of the reservoir were correct. Where inconsistencies between the predicted and observed behaviour occur, the model is reviewed and adjusted until a new match (a so-called history match ) is achieved. The updated model is then used to predict future performance of the field, and as such is a very useful tool for generating production forecasts. In addition, the model is used to predict the outcome of alternative future development plans. The criterion used for selection is typically profitability (or any other stated objective of the operating company). 

The first results of computer-based assessment system application show that the benefits are obvious for repaired (without heat treatment) welds and complex defect configurations defect with height local increasing, group of defects, case analysis of defects interference and possible joining. 

For the practical evaluation of the algorithm described previously it is integrated into the NDT Sean Manager system (DBA Systems Inc, Melbourne, FL, U.S.A). This system allows film digitisation, display, evaluation and archiveraent of images /3,4/ and was developed for the needs of computer based industrial NDT film inspection. A snapshot of the user interfaee for wall thickness evaluation is shown in fig. 3. 

F.C. Bernstein, T.F. Koetzle, G.J.B. Williams, E. Meyer, M.D. Bryce, J.R. Rogers, O. Kennard, T. Shikanouchi and M. Tasumi, The protein data bank A computer-based archival file for macromolecular structures, J. Mol. Biol. 112 (1977), 535-542. 

New ways to represent structure data became available through molecular modeling by computer-based methods. The birth of interactive computer representation of molecular graphics was in the 196Ds. The first dynamic molecular pictures of small molecules were generated in 1964 by Lcvinthal in the Mathematics and Computation (MAC) project at the Electronic Systems Laboratoiy of the Massachusetts... 

There is a lot of confusion over the meaning of the terms theoretical chemistry, computational chemistry and molecular modelling. Indeed, many practitioners use all three labels to describe aspects of their research, as the occasion demands "Theoretical chemistry is often considered synonymous with quantum mechanics, whereas computational chemistry encompasses not only quantum mechanics but also molecular mechaiucs, minimisation, simulations, conformational analysis and other computer-based methods for understanding and predicting the behaviour of molecular systems. Molecular modellers use all of these methods and so we shall not concern ourselves with semantics but rather shall consider any theoretical or computational tecluiique that provides insight into the behaviour of molecular systems to be an example of molecular modelling. If a distinction has to be... 

Bernstein F C, T F Koetzle, G J B Williams, E Meyer, M D Bryce, J R Rogers, O Kennard, T Shikanouchi and M Tasumi 1977. The Protein Data Bank A Computer-Based Archival File for Macromolecular Structures. Journal of Molecular Biology 112 535-542. 

The first step in designing a new compound is to find compounds that have even a slight amount of usefulness for the intended purpose. These are called lead compounds. Once such compounds are identified, the problem becomes one of refinement. Computational techniques are a fairly minor part of finding lead compounds. The use of computer-based techniques for lead compound identification is usually limited to searching databases for compounds similar to known lead compounds or known to treat diseases with similar causes or symptoms. 

A recent trend in particle analysis has been the introduction of personal computer-based automation (3). Sophisticated software packages can be used to automate and speed up the analysis. In some cases these computers can even carry out continuous process control (qv) (see Computer technology). The latest machines also allow the measurements of smaller particles and can detect a wider range of sizes. Machines based on light-scattering principles are being more widely accepted by the industry because of speed. An average analysis takes from 1—2 min, whereas those based on sedimentation principles require from 10—120 min. 

The use of graphic displays as an essential element of computer-based instmctional systems has been exploited in a number of ways. Molecular modeling and visualization techniques have supplemented the traditional set of stick models in courses on organic and inorganic chemistry, and animation of molecular motion and of the progress or mechanism of chemical reactions has been a useful classroom tool. 

California), Sibyl (Tripos, Missouri), ChemX (Chemical Design, UK), BioGraf (Molecular Simulations, California), Charmm/Quanta (Polygen Corp., Massachusetts), PC Model (Serena Software, Indiana), ChemLab (ChemLab Inc., Illinois), and a large number of personal computer-based packages. 

Vendors such as SUN and MIPS introduced lines of computers based on RISC (reduced iastmction set computer) chips. These computers offered significant performance advantages over the CISC (complex iastmction set computer) minicomputers, at least for CPU-bound work. Although there are stiU active debates about what RISC and what CISC are, the essence of RISC is simplicity. 

Trends. The parallel-computing marketplace is one of rapid change. New companies are developing computers based on new ideas, some... 

Many database producers provide online access to thek databases or distribute thek databases on compact disc read-only-memory (CD-ROM) and so are also considered vendors or producer/vendors. Whereas numerical growth in vendors is indicated (Fig. 1), the success of the database industry is largely a result of the transition of the information industry from paper-based to computer-based services (see Computer technology Informiation RETRIEVAL, Inforitation STORAGE MATERIALS). Thus industry growth can also be measured in terms of the increase in use of computer-readable databases as exemplified by the number of searches. 

Rules may represent either guidelines based on experience, or compact descriptions of events, processes, and behaviors with the details and assumptions omitted. In either case, there is a degree of uncertainty associated with the appHcation of the rule to a given situation. Rule-based systems allow for expHcit ways of representing and dealing with uncertainty. This includes the representation of the uncertainty of individual rules, as weU as the computation of the uncertainty of a final conclusion based on the uncertainty of individual rules, and uncertainty in the data. There are numerous approaches to uncertainty within the rule-based paradigm (2,35,36). One of these approaches is based on what are called certainty factors. In this approach, a certainty factor (CF) can be associated with variable—value pairs, and with individual rules. The certainty of conclusions is then computed based on the CF of the preconditions and the CF for the rule. For example, consider the foUowing example. 

E. H. ShortHffe, Computer-Based Medical Consultations AIYCIN, Elsevier, New York, 1976. 

In the absence of a rislc allowance the cost of capital becomes a technical financial computation based on sources of funds and company policy. As such it will usually be presented as a figure specified For use in a particular appraisal and is therefore of little concern to the projec t assessor. However, the following resume indicates the lands of Factors to be considered. 

Although a number of studies were made and approximate methods developed for predicting the effect of liquid holdup in the period of the 1950s and 1960s, as summarized in the 6th edition of Peny .s Chemical Engineers Handbook, the complexity of the effect of liqmd holdup is such that it is now best to use computer-based batch-distillation algorithms to determine the effect of holdup on a case-bycase basis. 

CCPS Y-28. Management of Change—Computer Based Training Module. American Institute of Chemical Engineers, Center for Chemical Process Safety, New York. 

Training is delivered via classroom, on-the-job, computer-based, or self-study programs. Tests and performance observations measure understanding. 

---