Resteaming Time Determination-Case History Of a Steam-Soak Well in Midway Sunset

Abstract

The steam-soak process has been one of the most successful applications of thermal recovery in California's oilfields. The performance of a typical well in the Buena Fe Fee lease in the Midway Sunset field is studied to show the phenomena apparent in other wells on the lease. Introduction About 15 percent of California's oil production comes from thermally stimulated wells, where the latest technological advances are used to satisfy the ever-increasing demand for oil.One of the most successful applications of thermal recovery has been in the steam-soak process, also known as "huff and puff," or steam stimulation. This method requires one of the highest levels of good engineering, operational analysis, and supervision. Where the proper conditions exist, the results have been rewarding and generally profitable. During the last few years, extensive drilling has taken place in many old leases containing heavy, viscous oil. The additional drilling could not have been possible without the incentive of higher production rates resulting from steam stimulation.The Midway Sunset field, in Kern and San Luis Obispo Counties, Calif., is one of the areas of greatest thermal-recovery activity. The field is one of the largest oil fields in California, having produced over 1.1 billion bbl of oil, second only to the Wilmington field. The Midway Sunset field is a unique accumulation of heavy petroleum hydrocarbons. Discovered in the late 1800's, petroleum hydrocarbons. Discovered in the late 1800's, the field is a huge regional north-northwest trending homocline along the east flank of the Temblor uplift, nearly 25 miles long and averaging 3 miles wide.The complex geology of the field has resulted in many pools and reservoirs of Pleistocene, Pliocene, and Upper pools and reservoirs of Pleistocene, Pliocene, and Upper Miocene age, comprising the Tulare, San Joaquin, Etchegoin Reef Ridge, and Antelope formations. Productive intervals for these zones range to over 6,000 ft in depth, although most of the heavy oil accumulations are found around 1,000 to 1,500 ft in depth. During 1972 and 1973, drilling in and production from this field reached the highest levels in its entire history.Thermal stimulation efforts for heavy oil leases in Midway Sunset were started in the early and middle 1960's. Considerable experimentation took place during the 1960's as the industry began testing the potential of thermal stimulation. With the publication of research reports and increasing operating experience, the ability and confidence of the industry in thermal processes grew. Thermal stimulation is successful in the production of many shallow, viscous oil reservoirs. Much research and experimentation continues today to gain a more complete understanding of the processes involved.The subject of this paper is the performance of a typical well in one of Atlantic Richfield's leases in Midway Sunset. The Buena Fe lease is a fee property located in Section 22, T32S, R23S, Kern County, Calif., on the western fringes of the central area of the field, about 2 miles west of the town of Taft. Limitation of the discussion to the entire life of one well in the lease presents an opportunity to show the phenomena that are presents an opportunity to show the phenomena that are apparent in many other wells in the lease. A section of this paper involves discussion of resteaming time, since this is one of the important facets of producing steam-stimulated wells.Although certain conclusions have been drawn for the Buena Fe lease, no implications of similar relationships for a general reservoir case are intended. JPT P. 665