Monitoring of swept volume over time is important for assessing the success of a thermal project. Falloff tests are commonly used to estimate swept volume for steam injection projects. Steam-injection falloff test data can be significantly affected by heat losses. A well test analysis method to include the effects of heat losses was published in Reference 1. However, one of its shortcomings is that the method requires a knowledge of the rock permeability to analyze test data.
This paper presents a practical method to overcome the proceeding and other shortcomings of the method presented in Reference 1. In our proposed modified method, we rely on pressure derivative graphs to identify the flow regimes, and to improve the analysis accuracy significantly. Numerically-simulated steam-injection falloff test data are analyzed using the previous methods and the modified method of this paper, showing the practicability and improvements resulting from the modified method of this paper.
The modified method presented in this paper should be of considerable help in analyzing falloff test data affected by significant heat losses. The modified method of this paper is also capable of demonstrating whether the effects of heat losses are significant for a given test data set.