Steamflooding in the U.S.: A Status Report

Abstract

Distinguished Author Series articles are general, descriptiverepresentations that summarize the state of the art in an area of technology bydescribing recent developments for readers who are not specialists in thetopics discussed. Written by individuals recognized as experts in the area, these articles provide key references to more definitive work and presentspecific details only to illustrate the technology. Purpose: to informthe general readership of recent advances in various areas of petroleumengineering. Summary This paper summarizes the history, current status, and future outlook ofsteamflooding in the U.S. The combination of increasingly restrictiveenvironmental regulations, the forecasted relatively low oil prices, anddeclining numbers of prices, and declining numbers of target reservoirs leadsto the conclusion that thermal EOR (TEOR) production in the U.S. has peaked. Future production will be affected more by production will be affected more byenvironmental constraints than by oil prices. Ongoing research to improveprices. Ongoing research to improve process technology could flatten theprocess technology could flatten the TEOR production decline. Historical Background Many experts would consider steamflooding a mature technology, even thoughit has really been practiced only since the early 1950's. It started in theU.S. with Shell Oil Co.'s steamdrive pilot in the Yorba Linda field inCalifornia in 1952 and later projects at Schoonebeek field in The Netherlandsand Tia Juana field in Venezuela. Fig. 1 (from Ref. 1) traces the short historyof steamflooding (compared with waterflooding as pressure maintenance). After arather slow pressure maintenance). After a rather slow experimental-phasestartup in the 1950's and early 1960's, when the industry had concentratedmostly on near-wellbore heating with downhole heaters and huff ‘n’ puffoperations. TEOR production spurted in the late 1960's. By then, the industryhad gained enough success from pilot testing and huff in' puff to makesignificant investments in steamflooding. Chevron U.S. A. Inc. began asignificant multipattern field test in the Kern River field in 1968. Themultiyear test was designed with two confined patterns, eight surroundingpatterns, and numerous observation wells to study the effects of heat and fluidmigration. This test provided important data for full-field expansion andlarge-scale operating problems; the observation-well data provided time-lapseinformation on the provided time-lapse information on the development of steamzones in the reservoir. The initial development of computersimulation modelswas reported in the early 1970's. Gomaa presented field-wide steamflood designand operating correlations based on symmetric pattern elements and uniformreservoir properties. These studies indicated a finite lifetime for steamfloodsand provided injection and production guidelines. Hongs reported criteria forconversion of steamflooding to waterflooding in the early 1980's. A waterfloodthat followed a steamflood was intended to scavenge injected heat and torecover additional oil for little added cost. These computer models providedcriteria based on production data-such provided criteria based on productiondata-such as oil/steam ratio (OSR), produced WOR, and average reservoirpressure-that could be used to estimate the optimum time for conversion towaterflood. In the early 1980's, major economic hurdles had been overcome, but not as aresult of any great technical breakthrough. World oil prices in 1979 allowedgreater flexibility, made more capital available, and accelerated anotherproduction growth spurt. During this optimistic period the California industryrapidly implemented new projects and expanded existing steamdrive operations. Projects were initiated with minimum background study and engineering design;in fact, some industry executives described such projects as "cash cows" because of the high income generated for low capital development costs. Mostforecasts predicted that heavy oil would be $50/bbl by the 1990's. During thisperiod steamflood reserves were added with existing injection wells by simplymoving uphole to flood the sands above the existing steamflood. Thus. highlyeconomical "vertical expansion" projects began. By 1986, steam stimulationprojects began. By 1986, steam stimulation and steamflooding technology were intheir teens and we, like most normal teenagers, "had all the answers." Fig. 1also shows the California OSRi.e., barrels of oil produced per barrels of steaminjected-for this growth period as more steamdrive projects were implemented. The declining OSR indicates the maturity of many of the best steamfloodprojects (implemented first) and the initiation of less desirable projects inlater years. During the early 1980's the need for efficiency was recognized butwas less critical; the price collapse of 1986 made it a major issue. ExcessOPEC production and pricing policies beginning in 1986 signaled pricingpolicies beginning in 1986 signaled a change in many of the basic assumptionsthat led to rapid growth in the early 1980's. Since 1986 the industry hasprioritized retrospective engineering analysis of field performance andcritically challenged performance and critically challenged operating costs andsteamflooding practices. We have looked again at the details of project design, production expectations, project implementation, and operating assumptions ofmany thermal recovery projects. This "field performance analysis," caused bythe price performance analysis," caused by the price collapse, indicates therelative immaturity of the process. We did not have all the answers. P. 548