| Water Flooding |
| The best known secondary oil recovery technique in which water is injected into the producing formation to maintain reservoir pressure and force the oil towards to producing well bore. Water flooding typically yields up to 80% of the conventional light crude oil and approximately 10% of heavy crude oil from a reservoir. |
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| Well Bore |
| The hole made by a well. |
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| Well Completions |
| Wells drilled to total depth and either prepared for production as oil and gas discoveries or found dry and abandoned. |
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| Well Log |
| A record of geological formation penetrated
during drilling, including technical details of the operation. |
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| Wellhead |
| The location of primary extraction, usually of oil or natural gas. The term also refers to the equipment used to maintain surface control of an oil or natural gas well and to various parameters, as they exist at the point of production (for instance "wellhead price".) |
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| Wellhead Price |
| The price paid at the wellhead for crude oil or natural gas production. |
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| Wet Barrel |
| An actual barrel of product physically present in storage at the time of a transaction, as opposed to a so-called "paper-barrel", which exists only as a credit on an accountant's ledger. |
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| Wet Combustion |
| An enhanced oil recovery technique applicable to heavy crude oil reservoirs and deep oil sands deposits (over 395 m deep), presently at the developmental stage. Also called fire flooding. |
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| Wildcat Well |
| A well drilled in an unproven area. Also known as an exploration well. |
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| Wildcatter |
| An operator who drills the first well in unproven territory. |
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| Wood Gasification |
| The production of a synthetic natural gas from wood. |
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| Wood Liquefaction |
| The production of liquids (e.g. methanol) from wood. |
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| Wood Waste |
| Fuel consisting of bark, shavings, sawdust and low grade lumber and lumber rejects from the operation of pulp mills, sawmills and plywood mills. |
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| Workover |
| Remedial work done to the equipment within
a well, the well pipework, or relating to attempts to increase the rate
of flow. |
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| World Crude Oil Price |
| A generalization for the "going" price of crude oil in international markets. |