American Institute of Mining, Metallurgical, and Petroleum Engineers, Inc.

This paper was prepared for the Rocky Mountain Regional Meeting of the Society of Petroleum Engineers of AIME, to be held in Denver, Colo., April 7–9, 1975. 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 request 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 discussion may be presented at the above meeting and, with the paper, may be considered for publication in one of the two SPE magazines.

Abstract

Laboratory experiments were performed in support of explosive fracturing-solvent injection research by the Energy Research and Development Administration in a shallow, heavy-oil reservoir near Bartlett, Kansas.

Tests were run on 25 solvents to determine their effectiveness in reducing the viscosity of the 2,820-cp oil and in preventing the precipitation of its 15 percent asphaltene content. The commercial solvent percent asphaltene content. The commercial solvent selected contains 74.3 percent aromatics to prevent precipitation; it lowers the oil viscosity to 73 cp when precipitation; it lowers the oil viscosity to 73 cp when 25 percent by volume is dissolved in the oil.

Fifteen oil recovery experiments were performed on lease cores using the solvent selected. Four solvent-soak experiments, simulating solvent injection into o fractured reservoir, showed that increase soaking time, surface-to-volume ratio, oil saturation, and temperature increased the amount of oil recovered per pore volume produced. Five solvent flooding per pore volume produced. Five solvent flooding experiments demonstrated the difficulty of forcing solvent through the highly oil saturated cores and the increased recovery rate caused by reversing flow. Five alternate water-solvent injection experiments, while using less solvent, overaged 10 percent less recovery than the solvent flood experiments. One experiment showed that continuous recirculation of the solvent could recover similar amounts of oil with less solvent than the solvent-soak experiments.

Introduction

Heavy oil and tar sands, because of their viscous nature, are not producible by ordinary crude oil production methods. Three elements must be present production methods. Three elements must be present for their production:

  1. establishment of communications between wells,

  2. reduction of oil viscosity within the formation, and

  3. maintenance of the flow path once established.

path once established. The Bartlesville Energy Research Center has devised a method of recovering heavy oil which meets these criteria in a consolidated sandstone formation. This method combines explosive fracturing techniques with solvent injection. Chemical explosives create fractures within the interwell zone as a means for establishing communications between the wells. The solvent lowers the viscosity of the oil contacted and maintains communication flow paths.

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