Application of Law of Equal Expectations to Oil Production in California

In February, 1918, the conclusion was published by Lewis and Beal ?thatwells of equal output on the average will produce equal amounts of oil in thefuture, regardless of the ages of the wells.? This conclusion was based uponthe study of data collected principally in Oklahoma and was not known at thattime to be true for other oil fields. An abundance of statistical proof waslater collected by the senior author of the present paper, which showed thatthe conclusion was undoubtedly well founded and that it applied to other fieldsas well. Accordingly, it was later restated as the ?law of equal expectations?as follows: ?If two wells under similar conditions produce equal amounts duringany given year, the amounts they will produce thereafter, on the average, willbe approximately equal, regardless of their relative ages.? Although only scanty data from the California oil fields were available at thetime this publication was prepared, sufficient information was analyzed uponwhich to base the insert on Fig. 80, which showed beyond a doubt that the lawheld at least for a part of the Midway oil field in California. Recently theauthors have collected more complete data in California, and it is the purposeof this paper to explain the method used in demonstrating the truth of the lawand, in addition, to give several methods by which curves constructed inaccordance with this law can be used in a practical way with ease andaccuracy. AIME 065–30