Steamflooding

Abstract

Distinguished Author Series articles are general, descriptive representations that summarize the state of the art in an area of technology by describing recent developments for readers who are not specialists in the topics discussed. Written by individuals recognized as experts in the area, these articles provide key references to more definitive work and present specific details only to illustrate the technology. Purpose: to inform the general readership of recent advances in various areas of petroleum engineering. Introduction Steamflooding has become an established recovery technique within the last20 years. This overview discusses its evolution, methods for selecting and designing steamfloods, constraints, and possible improvements. The term steamflooding is used here in a general sense. The discussion includes steamsoak (cyclic steam injection) and steam drive. For additional information the reader should refer to Farouq Ali and Meldau. Early Developments: Steam Soak There are records of steam injection into a Texas oil reservoir as far back as 1931. Steam drive on a sustained basis, however, did not begin until 1959–60 when Shell affiliates undertook steamflood pilots in Schoonebeek, the Netherlands, Mene Grande, Venezuela, and Yorba Linda, CA. Steaming operationsstill under way at Schoonebeek and Yorba Linda are discussed later. Venezuela. The steamdrive pilot in Mene Grande led to development of the steamsoak process. While attempting to relieve the formation pressure by opening a steam injector to production, oil was produced surprisingly at a rate of 100 to 200 B/D. produced surprisingly at a rate of 100 to 200 B/D. This was the first steamsoak well. This process underwent considerable development in both Venezuela and the U.S. Most of the oil produced by steam from 1960 to 1970was by this process. Typically, steam is injected for several weeks and then the well is closed in (soaked) until the steam has condensed, A pump then is run and the well is placed on production. When oil production falls to a lowlevel, the cycle is repeated. Thermal production in Venezuela is still almost entirely (95%) from steam soak. Compaction of these thick, unconsolidated sands together with solution-gas drive is leading to satisfactory oil recovery atvery high ratios of oil recovered per barrel of steam used. The Netherlands. One of the first large-scale steam drives began at the Schoonebeek field in The Netherlands in 1960. Recovery of the moderately viscous oil (180 cp) was quite successful. This encouraged additional fieldtrials of steam drive in the U.S. and in Venezuela. Coring showed that steamwas achieving low residual oil saturations of the order of 8%. The residual oilin the zone swept only by hot water was about 35%. Later tests at Schoonebeek were carried out at high pressure and high temperature. Under these conditionsCO2 and H2S are generated in situ. Consequently, new alloys had to bedeveloped. Thus, Schoonebeek led to pioneering along both reservoir andmetallurgical lines. U.S. Commercial steamflooding began in the U.S. in 1960 in the Yorba Lindafield, CA. JPT p. 237