Feasibility of Multi-Physics Reservoir Monitoring for Heavy Oil

Abstract

A new microseismic-electromagnetic (EM) acquisition system for reservoir monitoring includes surface and borehole hardware, processing software and interpretation methodology. For heavy oil reservoirs it allows mapping of steam/water flood fronts and surveillance of cap-rock integrity. The new array acquisition architecture combines novel technologies which reduces operational cost, due to unlimited channels capability: EM and microseismic acquisition is in the same receiver node to optimize the synergy between the methods. While microseismic channels address seal integrity information, EM data are used to track fluids, due to their high sensitivity to the fluid resistivity. The fluid resistivity drops strongly with mobility increase and pore size variation. Dense data further reduce the cost per receiver in a surface location. EM channels provide three-component (3C) electric and 3C magnetic data acquired on the surface and in shallow vertical boreholes. For later versions and deeper reservoirs deep wireline receiver with through casing measurement capabilities are planned. We include in the system an independent physics verification measurement using a differential approach to the surface data called focused source EM (FSEM) with practically little cost. Carrying out feasibility for each reservoir is key to control risk and cost. The feasibility includes 3D EM modeling, which allows integrating typically complex nature of the reservoir, and on-site EM noise test to tie 3D modeling to actual measured voltages. 3D modeling feasibility for a heavy oil reservoir proves the methodology to monitor the boundaries of the steam flood with accuracy and with high fidelity. Above the edges of the flooded (higher-temperature – lower-resistivity) area the results predict time-lapse EM anomaly exceeding 500%. The entire system is coupled with processing and 3D modeling/inversion software, significantly streamlining the workflow for the different methods. The system is capable of measuring and integrating the 3C of the electric field and 3C of the magnetic field in order to map the steam front and at the same time measuring microseismic occurrences in order to monitor seal stability. Channels capability of the system is practically unlimited allowing a denser coverage of the area in order to increase resolution and improve inversion.

Using Cloud-Based Array Electromagnetics on the Path to Zero Carbon Footprint during the Energy Transition

“…Monitoring of steam injected becomes extremely critical to lower the number of emissions. Resistivity can change up to 150 % for a temperature increase of 100 O C. Several feasibility studies were carried out in the last decade [37,38] and we present below selective results one of these in this context.…”

An Array Multi-Physics Acquisition System with Focus on Reservoir Monitoring

“…Only using a very stable and accurately current controlled transmitter and long-term stable receivers allowed this. Further survey design like this for heavy oil reservoir monitoring can be found in [21]. Above we introduced a shallow borehole measurement to get better image focus and stronger anomalies.…”

“…From the 3D modeling, we derived as key requirement that borehole and surface data needed to be integrated by measuring between surface-to-borehole and calibrated using conventional logs including the resistivity anisotropy. This would significantly reduce the risk in interpretation [21][22][23][24][25].…”

“…Figure21. Example of interpreted and integrated composite image including high resolution MT, gravity and seismic (left).…”

Using Cloud-Based Array Electromagnetics on the Path to Zero Carbon Footprint during the Energy Transition

“…Several feasibility studies were carried out in the last decade [38,39] and we present below selective results one of these in this context. Figure 17 shows the geologic section of a representative heavy oil field.…”