Experimental Analysis of Steam Foam Injection to Heavy Oil Limestone Reservoirs

Abstract

Abstract The applicability of steam foam injection process to Bati Raman heavy oil reservoir of process to Bati Raman heavy oil reservoir of Turkey was investigated by running a series of laboratory experiments. After static and dynamic screening tests, two surface active agents which showed foaming ability and permeability blockage were selected as foaming agents to be used during the steam foam injection tests in a linear laboratory model. Continuous steam injection was applied to a heavy oil and water saturated carbonate model with the selected surface active agents at different slug sizes to investigate their ability in decreasing the steam override. During these experiments steam front profile was modified after creation foam in-situ in the model and as a result depending on the type of the foaming agent, up to 45.6% incremental oil was recovered compared to a continuous steam injection test. The most efficient foam slug size was found as 0.17 PV when the foaming solution had 1.0 % weight concentration. Introduction Steam injection is one of the most successful enhanced oil recovery techniques which was extensively applied in the field since its development in the 1950's. The advantage of using this technique over other enhanced oil recovery methods is due to its versality and high recovery. The principal mechanisms responsible for the additional recovery of oil had been identified by Wilmann et al as thermal expansion of oil, viscosity reduction and steam distillation. Steam injection is being applied in many fields of USA, Venezuella, Holland, France, Indenozia, West Germany, Czechoslovakia, Canada and USSR which, contain medium, heavy and extra heavy crude oil. As of 1985, in USA 400,000 bbl, in Venezuella 170,000 bbl and in Canada 30,000 bbl of total daily oil production are obtained from steam injection projects. Although steam injection processes are well proven methods and are widely used to recover oil proven methods and are widely used to recover oil economically from reservoirs, because of steam overriding the resultant oil recovery, most of the time, is less compared to preplanned value. The most practical way of correcting this problem seems to be preventing the flow of steam problem seems to be preventing the flow of steam into the already swept zones and by controlling its mobility. The use of foaming agents as a mobility control as well as a blocking agent has been proposes by R.E. Dilgren and in the last few years the concern to develop the use of additives has grown. Nevertheless, the use of additives, in steam injection process in general, is still in a state of development and in the case of foaming agents, the mechanisms by which these additives improve oil recovery have not been completely understood. Almost all of the research studies on this subject are on the usage of foaming agents in sandstones and not much data exists on the use and efficiency of the surface active agents in carbonates, basically limestones. The present study is on the use foaming agents during continuous steam injection applied to limestone models saturated with heavy oil and water. P. 371