Experimental and analytical studies of cyclic steam injection using horizontal wells

A mathematical model has been developed that satisfactorily describes the results of laboratory scaled-model experiments of cyclic steam injection using horizontal wells. The physical model consists of an insulated aluminum parallelepiped containing a mixture of sand, water, and oil. The 1:396 scaled-model has internal dimensions of 10 in. in length and breadth and 5 in. in height, representing half of an actual 5-acre reservoir drainage area measuring 330 ft. in length and breath and 165 ft. in thickness and containing 1.85 MMSTB oil. Steam injection rates and reservoir pressure for the model are properly scaled to represent field values of 3,500 cold water equivalent barrels per day per well and 1,000 psia respectively. An experimental run consists of up to six cycles, each cycle representing (in the field) an injection period of up to 632 days, up to a shut in period of 178 days, and up to 2604 days production period. Runs are made with the horizontal well placed on one side of the model in two vertical positions, namely, at mid reservoir height and at reservoir base.;The analytical model consists of dividing the horizontal wellbore section into discrete intervals based on time-step specified. Heat and material balances are performed for each interval, from which advancements of the steam zone in the reservoir and in the wellbore are determined. Results of temperature, pressure, and produced oil and water volumes based on the analytical model are in good agreement with the experimental data.;Main research findings are that (i) steam reaches the horizontal well toe if the injection rate and injection time exceed certain minimum values, depending on the reservoir properties and well configuration, and (ii) the steam zone is not cylindrical but somewhat conical in shape, the steam zone radius being largest at the heel of the well. These research findings and the analytical model are expected to be of significant value to industry. It is recommended to conduct further research in which tubing, larger than 1/8 in. utilized in this study, is used as the horizontal well to better simulate steam displacement of the wellbore contents.