Worth

It must be emphasized that it is not worth expending any effort optimizing pressure, feed condition, or reflux ratio until the overall heat-integration picture has been established. These parameters very often change later in the design. 

P = present worth of estimated capital cost F = future worth of estimated capital cost... 

After the first year, the future worth F of the capital cost present value P is given by... 

The future worth of the second annual payment after (n - 2) years is... 

The fluid properties of formation water may be looked up on correlation charts, as may most of the properties of oil and gas so far discussed. Many of these correlations are also available as computer programmes. It is always worth checking the range of applicability of the correlations, which are often based on empirical measurements and are grouped into fluid types (e.g. California light gases). 

Finally, it is worth remembering the sequence of events which occur during hydrocarbon accumulation. Initially, the pores in the structure are filled with water. As oil migrates into the structure, it displaces water downwards, and starts with the larger pore throats where lower pressures are required to curve the oil-water interface sufficiently for oil to enter the pore throats. As the process of accumulation continues the pressure difference between the oil and water phases increases above the free water level because of the density difference between the two fluids. As this happens the narrower pore throats begin to fill with oil and the smallest pore throats are the last to be filled. 

Appraisal activity, if performed, is the step in the field life cycle between the discovery of a hydrocarbon accumulation and its development. The role of appraisal is to provide cost-effective information with which the subsequent decision can be made. Cost effective means that the value of the decision with the appraisal information is greater than the value of the decision without the information. If the appraisal activity does not add more value than its cost, then it is not worth doing. This can be represented by a simple flow diagram, in which the cost of appraisal is A, the profit (net present value) of the development with the appraisal information is (D2-A), and the profit of the development without the appraisal information is D1. 

It is worth noting that if field development using horizontal wells is under consideration, then horizontal appraisal wells will help to gather representative data and determine the benefits of this technique, which is further discussed in Section 9.3. 

It is worth noting that typically personnel and logistics represent 30% to 50% of operating costs while maintenance costs represent 20% to 40% of operating costs. These are particular areas in which cost control and reduction should be focused. This may mean reviewing the operations and maintenance philosophies discussed in Section 11.0, to check whether they are being applied, and whether they need to be updated. 

One particular common piece of legislation worth noting is the requirement for an Environmental Impact Assessment (EIA) to be performed prior to any appraisal or development activity. An EIA is used to determine what impact an activity would have on the natural environment (flora, fauna, local population), and will be used to modify the activity plan until no negative impact is foreseen. More details of the EIA are given in Section 4.0. 

It is worth to mention that the approximation is almost as good in the evaluation area as in the training area. In other words, we seem to have found a regression model with good generalization properties. 

As referred to above, most of the modules involve the intervention of a third party, the so-called notified bodies. These bodies are designated by Member States as being competent to carry out the certification tasks for which they are notified. As a precondition for their notification they must fulfil the minimum criteria which are set out in the relevant directives. These conditions vary from independence, impartiality and professional integrity, to technical competence, possession of or access to necessary facilities and to liability insurance. Once notified, the Commission publishes a list of all notified bodies in the Official Journal, It is worth noting that there is free competition between notified bodies and that manufacturers can make their own choice from all notified bodies notified within the European Union. 

J. F. Padday, Pure arul Applied Chemistry, Surface Area Determination, Butter-worths, London, 1969. 

Several reactivity trends are worth noting. Reactions that are rapid frequently stay rapid as the temperature or centre-of-mass kinetic energy of the reactants is varied. Slow exothenuic reactions almost always show behaviour such tliat... 

At this point it is worth comparing the different techniques of contrast enliancements discussed so far. They represent spatial filtering teclmiques which mostly affect the zeroth order dark field microscopy, which eliminates the zeroth order, the Schlieren method (not discussed here), which suppresses the zerotii order and one side band and, finally, phase contrast microscopy, where the phase of the zeroth order is shifted by nil and its intensity is attenuated. 

BO approximation vanishes even at low energies, hence the formulation of generalized BO equations become worth while considering. 

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