RIASSUNTO
Abstract
The Lance Creek Sun dance reservoir provides a case history of 10 yearsperformance of a reservoir in which unit operation has permitted effectiveutilization of gravity drainage augmented by primary pressure control withinjection of gas in to top structural wells. Detailed performance of thereservoir is presented by means of maps of well status, reservoir pressure,individual well recovery, etc., and by pool-performance charts. Analysis ofreservoir performance indicates only minor water encroachment, so that gravity,injected gas, and expansion of gas are the main oil-expulsive agents.
A simplified theory of regional drainage of oil from upstructure location todownstructure location due to gravity is presented and
checked by means of comparison of ""reservoir"" permeability and""well"" permeability from the pool performance. Good order of magnitudeagreement was obtained.
Individual well performance and overall reservoir performance indicatepossibility that maintenance of pressure makes ineffective those parts of thereservoir in which permeability is too low to permit effective drainage of oilby action of gravity. Oil from these parts can be recovered only when pressureis reduced locally by selective withdrawal or when overall reservoir pressureis finally reduced.
Introduction
The Lance Creek oil field, Townships 35 and 36N, Range 65W, Niobrara County,Wyoming, was discovered in October 1918, when Ohio Well No. State I wascompleted in the Dakota horizon at a depth of 3665 ft, with an initialproduction of 1500 bbl daily.
T.P. 2401