Experimental Investigation of Steam Soaking In a Depletion-Type Reservoir
Authors: Niko H. , Troost P.J.P.M. 
Published: December 2007

Scaled experiments with a physical model show that the production performance of a steam-soaked well is somewhat insensitive to the performance of a steam-soaked well is somewhat insensitive to the injection rate and soak time over a wide range of values. Stimulated oil productions are proportional to the drawdown, and the increase in productivity index is higher when the viscosity of the oil is higher. productivity index is higher when the viscosity of the oil is higher. Introduction

In the 11 years since its discovery, steam soaking has developed into a powerful stimulation technique. The process involves the cyclic injection of limited amounts of steam into a well, alternated with the production of hot oil from the same well. The steam production of hot oil from the same well. The steam heats the reservoir in the vicinity of the wellbore, and thus causes a reduction in the oil viscosity where the converging oil stream experiences the highest resistance to flow. This effectively increases the oil production rate. A significant improvement, however, will production rate. A significant improvement, however, will be obtained only in reservoirs where sufficient primary energy is available to drive the oil towards the well. Whether a well will respond to steam soak can readily be determined in the field. The well's performance for different injection and production policies can be resolved only in the long run. So we have made this the subject of a laboratory study using scale-model experiments, where the reservoir properties of the Bolivar Coast fields have been used as a general guide for the design of the model. The results of these experiments provide information on how such operating various as slug size, cycle length, steam injection rate and length of the soak period affect the production of a single well and that of a project with many wells. Different values of initial reservoir pressure, oil viscosity and layer thickness have been used. For our purposes, the effect of formation stratification was not considered, and wells were assumed to have no skin. Although this information is indispensible when determining optimum development schemes in the field, we do not deal here with optimization because it depends largely on economic factors, which vary widely with local conditions.

Experimental Setup and Operating Procedure

The model represents a cylindrical, bounded part of a depletion-type reservoir with a well in its center. The sand layer is horizontal; its thickness and permeability are constant. The model is provided permeability are constant. The model is provided with cap and base rocks. The production mechanisms (rock compaction, oil expansion, solution-gas drive, etc.) are accounted for by an increased effective oil compressibility, which is assumed to be constant. Because of the symmetry of the prototype, the model has to represent only a sector of it (Fig. 1A). The glass side walls wore insulated with polystyrene to minimize lateral heat losses. Model studies of steam soak in depletion-type reservoirs require the scaling of both the depletion process and the effect of the steam. The process and the effect of the steam. The steam-injection scaling rules are discussed in Appendix A. They determine the model values of permeability, viscosity, and quality of the injected steam. If we combine these requirements with those for the simulation of the depletion process, it appears that the compressibility of the model oil must be 50 to 100 times as high as that of the prototype oil.

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