E.I.S.

An environmental impact statement which is required by many environ- mental authorities before a project can proceed.

Easting

The distance a craft makes good to the east. The opposite is westing. In a cartesian reference system the value of one coordinate, usually ex- pressed in metres used, measured from the central meridian in east-west direction; e.g. in the UTM system.

EBCDIC

Extended Binary Coded Decimal Interchange Code. The data format is used in the seismic industry for data acquisition and storage.

ECDIS

Electronic Chart Display and Information System.

Echo sounder

An acoustic water depth measurement instrument, hull mounted or tracked to the hull of a vessel; raw data is corrected for water velocity, ship draft and tidal variations, and often digitised for automated bathymetric chart production. Recent development of multibeam or swathe sounders are not in common use.

Echo sounding

Determination of the depth of water by measuring the time interval between emission of a sonic or ultrasonic signal and return of its echo from the bottom. Also called acoustic sounding. See echo sounder.

Economic limit

The minimum rate to which the production of a well may decline and still be profitable.

Economic project

A project that appears likely to yield an acceptable net income after paying all costs, royalties, taxes, etc.

Edge water

Water underlying and/or marginal to an oil or gas reservoir.

Effective permeability

A measure of the ability of a single fluid to flow through a rock when the pore spaces of the rock are not completely filled or saturated with fluid. Compare absolute permeability and relative permeability.

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