This paper was prepared for the 96th Annual AIME Meeting to be held in Los Angeles, Calif., Feb. 19 through 23, 1967. Permission to copy is restricted to an abstract of not more than 300 words. Illustrations may not be copied. The abstract should contain conspicuous acknowledgment of where and by whom the paper is presented. Publication elsewhere after publication in the JOURNAL OF PETROLEUM TECHNOLOGY or the SOCIETY OF PETROLEUM ENGINEERS JOURNAL is usually granted upon requested to the Editor of the appropriate journal, provided agreement to give proper credit is made.

Discussion of this paper is invited. Three copies of any discussion should be sent to the Society of Petroleum Engineers Office. Such discussions may be presented at the above meeting and, with the paper, may be considered for publication in one of the two SPE magazines.

Abstract

The thermal stimulation of oil producing wells by cyclic steam injection accounts for over 11 per cent of the current oil producing rate in California. This paper outlines some of the more important steam soak operations being conducted in 3-, California oil fields up to June, 1966.

Theoretical predictions of initial oil rates after steaming, which have been previously presented in the literature, are discussed and compared with actual case histories. Factors, which may influence the amount of oil recovered per cycle are also summarized. To facilitate the comparison of cycles, the oil product o data have been plotted on log-log paper. discussion of this method is presented together with several illustrations.

The costs of steam soak operations are discussed with emphasis on the determination of economically successful operations. A total of 37 fields in the San Joaquin Valley, Coastal and Los Angeles Basin areas are reviewed. In June, 1966, steam soak operations on a fieldwide basis appear to be economically successful in only 10 fields. The performance of five successful and five unsuccessful operations are presented for comparison purposes, and some of the reasons for the successes and failures are discussed.

Introduction

The tremendous upsurge in thermal stimulation of heavy oil producing wells by steam soak operations in recent years has reversed the nine-year decline trend of the total oil production rate in California. By the end of June, 1966, some 5,300 wells were actively involved in steam soak operations and over 110,000 B/D of additional oil being credited to this thermal stimulation process. The total state production has increased from 795,238 B/D in Feb., 1962, to 939,704 B/D in June, 1966.

This paper reviews briefly the status as of June, 1966, of the steam soak operations in 37 California oil fields. The cost of steam cyclic operations are examined in an attempt to determine those economically successful projects in the state. The production data are most readily available on a field-wide basis and the review has been conducted in this manner. Acknowledging the limitations of using field data, it must be realized that the Average data on certain successful fields may conceal various projects that are failures and, conversely, successful projects may exist in fields that appear to be over-all failures.

Two theoretical methods of predicting initial oil producing rates after steaming are reviewed, and comparison between theoretical predictions and actual rates are made.

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