In-situ steam generation using electrical resistance heating

Abstract

This work presents a new application of Electrical Resistance Heating (ERH), in-situ steam generation (ISSG). ISSG uses ERH to generate steam in-situ for steam flooding. The heat generated by ERH comes from the flow of low frequency electrical current through the formation. The ERH process has been studied by several authors[^1'13]. Previously studied applications of the ERH process have concentrated on oil production wells and water injection wells. These applications have mainly been conducted below the boiling point of water to avoid the problem with increasing formation resistivity due to water vaporization. The objective of this work was to study the engineering aspects of the ISSG process. A numerical finite difference 2-D, r-z simulator was developed for this study. The simulator consists of a fluid and energy flow model, an electrical flow model, and an over and underburden model. This study considered two processes: A) single injection well and B) cyclic steam injection. A variation of the Fourth SPE comparative study^16 was used as the base case. For the single injection well process, the variables studied were electrode length, electrode placement, injection interval, and ERH rate. For the cyclic steam injection process, the variables studied were heating during the production cycle, rate of ERH, and rate of water injection. The ISSG process may be used as an alternative to conventional steam injection (CSI) when either physical or environmental restrictions prohibits the use of CSI. The fuel cost ratio of the ISSG process to CSI appears to be at least 5.5. The steam injection study indicates that the efficiency of the ISSG process increases by decreasing the length of the electrode. The study also shows that water vaporization can be controlled by limiting water the injection interval to the electrode interval. The cyclic steam injection work show that: 1) heating during the production cycle is very ineffective, 2) the effect of increasing the electrical power is most effective when no steam is present during the injection cycle, and 3) the effect of increasing the water injection rate is most effective when steam is present during the injection cycle.