Steam Flood Pilot, Nacatoch Sand Troy Field, Arkansas
Authors: Connally C.A. , Marberry J.E. 
Published: December 2007

This paper was prepared for the Improved Oil Recovery Symposium of the Society of Petroleum Engineers of AIME, to be held in Tulsa, Okla., April 22–24, 1974. 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 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. 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.

A test of steam flooding to improve recovery of 14 degrees API, 7,000 CPS oil from the Nacatoch sand was conducted in a 15 acre inverted 5-spot pattern in Troy Field, Arkansas. Five observation wells within the pattern were used to monitor temperature and pattern were used to monitor temperature and pressure. Oil saturation was about 50 per cent pressure. Oil saturation was about 50 per cent of pore space when steam injection began after a long history of pressure depletion and edge water influx. Steam fingered a distance of two well locations (1,200 ft) outside the pilot pattern while reaching only two of the pilot pattern while reaching only two of the pilot producers. Ultimate areal sweep within the producers. Ultimate areal sweep within the test pattern was about 50 per cent. invasion efficiency of the steam zone in the 20 ft thick sand was approximately 40 per cent with gravity override causing steam to move to the upper part of the sand. Oil recovery from the part of the sand. Oil recovery from the pattern during steam drive was about 10 per cent pattern during steam drive was about 10 per cent of the oil in place and the steam/oil ratio was 12 bbl/bbl. Injection of water subsequent to steam resulted in recovery of an additional 6 per cent. It was concluded that closer well spacing would likely enhance recovery but would be uneconomic.

Introduction

The Upper Nacatoch sand reservoir in Troy Field, Arkansas was developed in the late thirties and produced by pressure depletion accompanied by natural water influx. By the mid sixties wells were pumping about 90 per cent water cut with oil rates generally less than 10 bbls per day per well. Reservoir pressure had decreased to the range of 50 to pressure had decreased to the range of 50 to 75 psig. More than 1,500 bbls per acre-ft of the heavy, viscous oil (14 degrees API, 7,000 cps) was estimated to remain in place. This substantial remaining oil content prompted consideration of methods for improving recovery.

Laboratory tests of steam flooding of the crude in a sand packed tube indicated that steam might be effective in displacing the oil to very low residuals in the swept region. An earlier test of steam stimulation of a producing well showed that steam could be readily injected at the desired rate and pressure. An ample supply of fresh water for steam generation was locally available from a shallow water sand. With these favorable considerations. a pilot test of steam flooding was initiated in January 1966.