Measurement of Formation-Resistivity Changes Induced by in Situ Combustion

摘要

Use of controlled source audio magnetotelluric (CSAMT) techniques to map thermal fronts associated with enhanced oil recovery (EOR) processes depends upon knowledge of the changes in formation electrical resistivity. Measurement of these changes required the development of a technique which survives high temperatures and a very corrosive environment while measuring over a frequency range of 5 to 5000 Hz. The apparatus to make these measurements is described. The results from a laboratory forward dry combustion test in the University of Calgary combustion tube are presented. It is found that there is a two-decade change in the resistivity as the fire front traverses through a region. Also there are indications of the separate zones within a fire front. The importance of these results to interpreting CSAMT data are then considered. The frequency dependence of the resistvity changes suggests means of increasing CSAMT sensitivity for deep oil pay-zone mappings. 4 figures. (ERA citation 07:052665)