A Laboratory Investigation of Fire-Water Flooding

Abstract

Abstract The results of a systematic investigation of the parameters of fire-water flooding are reported. The parameters of fire-water flooding are reported. The results were obtained from a series of 131 combustion-tube tests. Experimental equipment and procedures were developed to minimize heat-transfer procedures were developed to minimize heat-transfer problems and transient effects at the inlet of the problems and transient effects at the inlet of the tube. The tests were performed with water/air injection ratios from 0 to 13 cu ft/Mscf, using crudes with gravities from 10 degrees to 48 degrees API, in waterflooded and nonwaterflooded sands at pressures of 0, 1,000, and 2,000 psig. The air requirements for fire-water flooding were reduced by more than 50 percent in some cases. Similar results were obtained with various crudes. Introduction The greater demand for crude oil, the increased difficulty of discovering new reservoirs, and the desire to reduce dependence on imports have emphasized the need for enhanced recovery methods capable of economically producing the crude remaining in known reservoirs. Numerous methods have been proposed and tested in laboratories and field pilots, and some have been used in commercial applications. Fire flooding is one enhanced recovery method that has been technically successful in many field applications. Some of these projects have been economically successful, but many are only marginally so. The high cost of air compression for fire flooding is one of the major factors that influence the economics. Large quantities of air are required per unit reservoir volume swept, especially for heavy crude, because all the residual material remaining in the sand immediately ahead of the combustion zone must be consumed. Only a portion of the heat generated is necessary for maintaining the movement of the combustion zone, and the remainder is left behind in the depleted sand. Fire-water flooding is a recovery technique that was conceived to improve the economics of dry fire flooding. In this process, water is injected along with the air to recover some of the heat remaining behind the combustion zone. At low water injection rates, the heat is transported through the combustion zone by superheated steam to where it can be utilized for preheating the reservoir. At higher water injection rates, the water partially quenches the combustion, reducing the maximum temperature to the steam-plateau level, and heat is transferred through the combustion zone as saturated steam. The air requirement is lower with water injection because the amount of hydrocarbonaceous material deposited on the sand grains is less and because all of this fuel is not necessarily consumed. At a constant air injection rate, the oil may be produced faster with water injection than without because of the more rapid combustion-zone movement, the increased utilization of energy, and the increased volume of fluid injected. Fire-water flooding has been investigated in several different laboratories with combustion-tube experiments. The feasibility of partially quenched combustion, the reduced air requirements, and the improved utilization of heat with water injection have been confirmed. However, the results of only a few experiments have been reported by each investigator, and only a limited amount of experimental information is available on the relationships of the fire-waterflooding parameters. in addition, it has been suggested that be results of wet combustion tests may be misleading because of experimental limitations. In this paper, the results of a systematic investigation of the parameters of fire-water flooding are reported. The results were obtained from combustion-tube tests. The equipment was designed to minimize heat-transfer problems, and operating procedures were developed that reduced the procedures were developed that reduced the transient effects at the inlet of the tube. SPEJ P. 537