ECONOMICALLY RECOVERABLE RESOURCE ESTIMATE - An assessment of hydrocarbon potential that takes into account (1) physical and technological constraints on production and (2) the influence of exploration and development costs and market price on industry investment in OCS exploration and production.
EFFECTIVE POROSITY - The percent of the total volume of rock that consists of connecting pores or interstices. The part of a rock that is capable of holding a fluid (oil, water, or gas) is the effective porosity.
ELECTRIC CABLE TRAY - supports the electrical cables that feed the power from the control panel to the rig motors.
ELECTRIC CONTROL HOUSE - On diesel electric rigs, diesel engines drive electric generators. The generators produce electricity that flow throw cables to electric switches and control equipment enclosed in a control cabinet or panel. Electricity is fed to electric motors via the panel.
ELECTRIC LOG -An electrical survey made on uncased holes. A special tool is lowered into the hole which ejects an electrical current into the rock and records its resistance to the current. The data from the survey is used by the geologist to determine the nature of the rock and its contents.
ELECTRIC RIG - a drilling rig on which the energy from the power source—usually diesel engines—is changed to electricity by generators mounted on the engines. The electrical power is then distributed through electrical conductors to electric motors. The motors power the various rig components. Compare mechanical rig.
ELECTRIC SUBMERSIBLE PUMPING - a form of artificial lift that utilizes an electric submersible multistage centrifugal pump. Electric power is conducted to the pump by a cable attached to the tubing.
ELECTRIC WELL LOG - a record of certain electrical characteristics (such as resistivity and conductivity) of formations traversed by the borehole. It is made to identify the formations, determine the nature and amount of fluids they contain, and estimate their depth. Also called an electric log or electric survey.
ELEVATOR LINKS - cylindrical bars that support the elevators and attach them to the hook.
ELEVATORS - on rotary rigs and top drive rigs, hinged steel devices with manual operating handles that crew members latch onto a tool joint (or a sub).
ENGINE - a machine for converting the heat content of fuel into rotary motion that can be used to power other machines. Compare motor.
ENVIRONMENTAL IMPACT STATEMENT - A statement required by the National Environmental Policy Act of 1969 (NEPA) or similar state law in relation to any action significantly affecting the environment, including certain exploration and drilling activities.
EROSION - the process by which material (such as rock or soil) is worn away or removed (as by wind or water).
EROSION/SCOUR - The removal or dissolution of parts of the seabed by bottom currents, particularly those by storms. Transportation by currents of the removed material can result in significant movement of masses of sand, silt , and mud on the sea floor. This migration of sediment can "strand" drilling platform supports or wellhead plumbing by erosion of the surrounding support sediments.
EVENING TOUR - the shift of duty on a drilling rig that generally starts in the afternoon and runs through the evening. Sometimes called afternoon tour. Compare daylight tour.
EXCLUSIVE ECONOMIC ZONE (EEZ) - An area contiguous to the territorial sea of the United States, the Commonwealth of Puerto Rico, the Commonwealth of Northern Mariana Islands, and the U.S. overseas territories and possessions and extending 200 nautical miles from the coastline.
EXPLORATION - The process of searching for minerals preliminary to development. Exploration activities include (1) geophysical surveys, (2) drilling to locate an oil or gas reservoir, and (3) the drilling of additional wells after a discovery to delineate a reservoir. It enables the lessee to determine whether to proceed with development and production.
EXTERNAL CUTTER - a fishing tool containing metalcutting knives that is lowered into the hole and over the outside of a length of pipe to cut it. The severed part of the pipe can then be brought to the surface. Also called an outside cutter. Compare internal cutter.