Overview
	Estimating Reserves
	Reserves Information

Reserves according to the Society of Petroleum Engineers' (SPE) definition are those portions of identified oil or gas resources that can be extracted using current technology. They represent quantities of hydrocarbons, which are anticipated to be commercially recovered from known accumulations from a given date forward.

The DOI is required under the OCS Lands Act to “...conduct a continuing investigation… for the purpose of determining the availability of all oil and natural gas produced or located on the Outer Continental Shelf.”  MMS’s Reserves Inventory Program represents a significant part of the Resource Evaluation scope and further contributes to:

	Energy supply forecasting;
	Public policy decisions;
	Independent assessment/verification;
	Assuring fair value in public/private transactions;

The reserves inventory component of the RE Program assigns new producible leases to fields and establishes field limits. The RE Program also develops independent estimates of original amounts of natural gas and oil in discovered fields by conducting field reserve studies and reviews of fields, sands and reservoirs on the OCS. The Program periodically revises the estimates of remaining natural gas and oil to reflect new discoveries, development information and annual production.

A field is an area consisting of a single reservoir or multiple reservoirs all grouped on, or related to, the same general geological structural feature and/or stratigraphic trapping condition. There maybe two or more reservoirs in a field that are separated vertically by impervious strata, laterally by geologic barriers, or by both. Hydrocarbons (gas and oil) estimated on the basis of geologic knowledge to exist outside of known accumulations are undiscovered resources. Hydrocarbons whose location and quantity are known or estimated from specific geologic evidence are discovered resources.