Shale rock physics: Improved seismic monitoring for increased recovery

In this project, tools (models) are developed for the industry to understand how the rocks located over the petroleum resources change when oil and gas are produced. These overlying rocks, termed as roof rocks (shales), enable accumulation of oil and gas in the underlying reservoirs over millions of years. This tool uses velocity (seismic) data from field measurements as input. It turns out that such data from the shales often provide new significant information, beyond the information attainable from the underlying reservoir alone. Examples of this are monitoring of deformations to avoid stability problems in existing and new wells as well as monitoring of fracture systems to prevent leaks, both commonly associated with the shaly roof rocks. The behaviour of the roof rocks is also essential for understanding how efficient and to what extent the oil and gas reserves are recovered. And finally, a safe and environmentally friendly utilization of natural resources is very important for the society as a whole. Such models are therefore of high importance for precise interpretation of the subsurface in the petroleum industry. The results of this project will contribute to improve the utilization of our petroleum resources, reduce costs and reduce the risk of unexpected events in connection with drilling and petroleum production. In this project we have made significant advances in the development of an advanced measurement method. This equipment enables controlled rock velocity measurements in the laboratory with a sufficiently low-frequency pulse, like what is extensively used for field measurements using seismic waves. Our PhD student has been a key person in this development. Additionally, we have also designed innovative measurement protocols that lead to much better utilization of the precious field material we are testing. SINTEF's Formation Physics Laboratory has gained recognition for the measurement methods and the results of this project from the industry and other collaborators. This is important for the long-term national competence base. An important success factor has been active participation in conferences, considerable publishing and, not least, regular dialogue with the industry. In the project period we have established cooperation with several outstanding international research groups such as EPFL in Lausanne, Universität Bern and Heriot-Watt University in Edinburgh. The project has also resulted in new projects (spin-offs) utilizing these advanced measurement methods and test protocols. Not only the petroleum industry has shown interest in the results. The low-frequency setup is also used in a project for the renowned National Agency for the Storage of Radioactive Waste in Switzerland (Nagra), which shows the potential of the applications for the advanced measurement methods developed beyond improved oil- and gas utilization. There are also indications that this method is of interest for the offshore service industry. A major challenge for the petroleum industry is to exploit the vast amount of data they are generating. A key objective of this project has been to make the results applicable, such that the industry can process their own data more efficiently and thus contribute positively to the ongoing digitization of the petroleum industry. This has been achieved through a close cooperation with the project's industry partners with significant user participation through a series of workshops. The main deliverable of the project (the toolbox) enables the industry to exploit our natural resources in a sustainable and efficient manner. This message has also been disseminated to a broader audience through popular science media. It is very satisfactory that the industry participants, who are heavily involved on the Norwegian continental shelf and in adjacent areas (Danish and British sector), state that they have already implemented project results in their organization or have concrete plans for this in near future.

The main result are tools for improved interpretation of seismic data for improved utilization of petroleum resources. One participant has already successfully implemented results in their workflow, and the other participants have concrete plans for this. We contribute to more precise predictions of deformations in the challenging rocks overlaying the petroleum resources, to avoid instable and dangerous zones, avoid leakages, and effectively reduce the number of "dry wells". These aspects are very important for the society as a whole, by optimizing the petroleum production at lower cost, higher safety and less carbon footprint. The project has also resulted in spin-offs. SINTEF's Formation Physics Laboratory has gained recognition for the results of this project from the industry and other collaborators. This is also important for the long-term national competence base, and as such place Norway into a unique position by providing advanced rock physics technology for versatile use.

This project will focus on the development of a reliable stress, strain, temperature and frequency sensitive rock-physics model for caprock shales relevant for the quantitative interpretation of time-lapse seismic data. Results of this project will contri bute to improved mapping of reservoir depletion, monitoring of EOR/IOR processes, identification of undepleted pockets, and optimising and de-risking infill drilling.