Resuspension of accumulated particles in residential networks is the main cause for customers to complain to the water company about the water quality. Preventing the particles from accumulating in these networks can be achieved by high velocities in pipes. Adding this velocity criterion to the conventional design criteria leads to a branched lay out of distribution networks, that perform better with respect to water quality, continuity of supply and investment costs. In close cooperation with fire brigades the conventional fire flow requirements were challenged. Based on modern building codes, it proved possible to reduce the capacity of fire-hydrants to 8.3 l/s (30 m3/h) in newly built areas. Six years after the introduction of the velocity criterion the characteristics of the newly laid networks have changed resulting in smaller diameter pipes and reduced length of networks. The amount of 100/110 mm pipes have dropped from 55% of the total length to 45% of total length. The total investment costs for new networks have dropped by 20% in the Netherlands.

Comsima is a mechanical model that calculates stresses and joint rotations in drinking water distribution pipes based upon several loadings on the pipe (soil, traffic, water pressure, differential settlements). Pipe degradation mechanisms (slow crack growth resistance for PVC and calcium leaching for AC) were added to the model. A comparison with failure registration for an area in the Netherlands using satellite data to determine differential settlements shows that pipes with higher stresses or higher joint rotations in general have a higher failure rate.

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Various general methods have been developed for giving analytical description to frequency distributions with single modes or maxima. Perhaps the best known methods are those coming from Pearson and Charlier. The work of the former is, on the whole, more accessible in this country and in England than is that of the latter.We shall not, in this discussion, enter into the advantages to be derived from giving analytical representation to frequency distributions. These advantages are obvious enough to anyone familiar with the statistical analysis of large bodies of data. To clarify subsequent discussion, however, we may refer briefly to the general method of analysis developed by Pearson.Pearson writes the differential equation to the generalized frequency distribution thus dx (x -a)ij dx b 0 -j-bix + b 2 x 2

For a green field, estimating fluid contacts can be challenging when there is large uncertainty due to the lack of fluid contact penetration by the appraisal wells, insufficient pressure data in oil or water legs, or ambiguous seismic amplitude shut off. For reserves booking, SEC Rule 4-10(a)(22) states that "In the absence of data on fluid contacts, proved quantities in a reservoir are limited by the lowest known hydrocarbons (LKH) as seen in a well penetration unless Geosciences, Engineering, or performance data and reliable technology establishes a lower contact with reasonable certainty." One way to ensure reasonable certainty conditions are met for contacts beyond LKH and to increase confidence for probable and possible fluid contacts that may be estimated using regional pressure trends is to analyze the seal capacity to check whether the seal would hold the hydrocarbon column associated with the proposed contacts.There are two methods for testing seal capacity within the framework of a capillary pressure model. One method uses the capillary entry pressure for a sealing layer (P seal ) to compute the maximum hydrocarbon column (H max_seal ) that a sealing layer (e.g. shale, silt, salt, anhydrite, etc.) can sustain without leaking. However, P seal data are usually not available since such lab measurements are not typically made with the sealing layers. The other method uses the shale fracture pressure (P frac ) estimated from a model that incorporates leak of pressure measurements across sealing layer to compute the H max_frac that the shale layer above the reservoir can sustain without fracturing.This presentation is aimed at sharing the approach using fracture pressure to analyze seal capacity, establishing reasonable certainty associated with proposed fluid contacts. Application of this method will be shown using examples from a Deepwater Nigeria field.