hispaper was presented at the 4th Middle East Oil Show, held in Bahratn, March 11-14, 1985. The msterisl is ubject to correction by the author. Pezmieeion to copy ia restricted to so abstract of not more than 300 !ords. Write: P.O. Box 833836. Richardson. TX 75083 ABSTRACT A number of major oil reservoirs in the Middle Eeet have a tar barrier between the oil.zone and the underlying water zone, with a strong bottom water drive. This investigation ia aimed at oil recovery from such reservoira.

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... cifically, it is intended to explore several recovery methods that could be used for increasing oil recovery from such reaervoira. AS far as one can aacertain, little or no work haa been published on this subject of vital importance inSaudf Arabia, Kuwait, and Iraq. The present investigation wsa axperi.mentalin nsture, utilizing several models, and a variety of recovery schemes. In all inatencea, three zones were initially set up in the models: a light oil zone on top, a water zone at the bottcsa,and a tar zone between the two. Tinethic"~esaea of the oii and tar zones were varied to cover a range of conditions. The bottom water zone was equipped with a water drive. The different recovery techniques tested were: (i) injectim of water into the oil zone (internal waterflood), without a bottom water drive, (ii) internal waterflood, with a bottcm water drive, (iii) bottomwater drive, (iv) injection of solvent into the tar zone, (v) injection of ateem into (a) oil zone, (b) tar zone, and (c) water zone. The results show that when waterflooding the oil zone, an important factor is the extent of communication between the water zone end the tar zone. Such communicatim can be established by use of eolventa or ste=, though such proceasea are admittedly inapplicable in some of the deeper formations. Once ccnmnunication ia attained, an internal waterflood can be very effective. With bottom drive alone, recovery wee found to be low in view of water channeling and coning. Solvent injection runs showed that large volumee of a suitable solvent will have to be injected in order to obtain the necessary communication. Steam injection into the ofl zone mitigated the benefita of a water drive. However, injection into the tar zone waa effective both in promoting the bottom water drive, and also in recovering some of the tar, although this was not a primary objective. Injection into the bottom water zone was largely ineffective, since the heating of the overlyfng tar layer requtred very large volumes of steam.