Forty Years of Steam Injection in California - The Evolution of Heat Management

Abstract

Abstract Steam injection EOR began in California forty years ago, and has been highly successful. As a consequence, California's thermal recovery operations represent a leading source of EOR production in the world. The understanding of most early thermal recovery operators was limited to the concept of "heat reduces heavy oil viscosity, and reduced viscosity means more production." Steam injection was attempted in almost any reservoir having viscous oil with little appreciation of other recovery process considerations. Although several early pilot projects were steamfloods, most early applications were cyclic stimulation. During the late 1970's, steamflooding became predominant, and many people considered steamflooding to be a displacement process (hence the term "steam drive"). With this paradigm and high oil prices, there was little impetus to understand efficient use of heat. The predominant philosophy was "If you want more oil, inject more steam." With the later collapse of oil prices, operators returned to review process fundamentals and to determine how to more efficiently operate steam projects. This paper discusses the shift to an override, or gravity drainage, model concept. This helped lead to reduced steam injection and improved thermal efficiency through the use of heat management. This paper discusses the shift to the concept of steam override and gravity drainage as steamflood recovery mechanisms and the subsequent use of heat management practices that improved thermal recovery efficiency. Thermal Recovery in California Early Days: 1960–1966 Early efforts to improve heavy oil productivity in California used bottomhole heaters or in-situ combustion. Bottomhole heaters did improve well productivity1, but their success was limited by both relatively small heat input rates and the fact that they depend upon conductive heat transfer from the wellbore to the formation. Although some success was obtained with in-situ combustion projects, the high fuel (coke) deposition from the heavy crudes resulted in high air requirements. This, coupled with the difficulty in operating and controlling the in-situ process, limited its application. The first official mention of steam injection in California was cyclic steam injection in the Yorba Linda Field in 1960.2 In 1961, cyclic injection began in the Kern River Field, and in 1962 two additional fields started cyclic steam (Coalinga and McKittrick), and steamflooding began in Kern River. Although companies were beginning to test steam injection, in-situ combustion was still popular, as five new combustion projects were begun in 1962.3 Secrecy surrounded the early steam tests as noted in this reference to testing in the Coalinga Field in 1962, "In other portions of the field, recovery of oil by various means of production stimulation appears to be on an increasing trend. The degree of success by these methods is a secret closely guarded by the operators, and little information has been made available to the public."2 However, neighboring operators were observant, and steam generators were difficult to hide. A dramatic expansion of steam injection projects was soon to follow.