Abandoned wells are a big problem. They require significant investment to be adequately sealed and pose risks to the environment due to the susceptibility of methane leakage. One alternative is repurposing the wells to geothermal energy, which would also save costs of drilling geothermal wells. This idea is not new, and many projects have attempted to demonstrate its feasibility. In our latest publication, we analyzed these projects and evaluated the challenges they faced.
Besides challenges with well integrity, legislation, and data availability, most wells are located in remote areas and have demonstrated low efficiency. Repurposing wells for geothermal energy might be one of the solutions to well abandonment, but it still requires future innovations to make it economically and technically feasible.

I recently had the opportunity to present to a diverse group of oil and gas regulators and inspectors from different states about the importance of cement evaluation in oil and gas wells. The talk was part of a training program provided by TOPCORP, a consortium created to reduce the knowledge gap between oil and gas inspectors and operators. I introduced the basic cementing principles, their importance in wellbore integrity, and the main tools used for evaluation. In the end, we evaluated some well logs together. The interaction was also a great learning opportunity to see how things works from a regulatory point of view. For instance, some states only require that the operator run cement logs only if the well is not cemented to the surface.

On the same day, I attended talks about orphan and abandoned wells, methane emissions, and pipelines. It was interesting to find how each state deals with regulations and how difficult it is to promote changes. States like North Dakota, where the oil and gas activities are more recent are more flexible and seem to be doing a better job dealing with abandoned wells, for example. However, changes are inevitable if we want to build a more sustainable future.

Shape memory polymers (SMP) are fascinating materials. They are smart materials with the ability to change shape when triggered by external stimuli. SMPs can retain two or sometimes three shapes, and the transition can be permanent or temporary. My research group has been studying them for years in different applications in the oil and gas industry, such as lost circulation materials, cement additives, proppants for hydraulic fracturing, and diverters for refracturing. In all cases, the SMP was programmed to expand when exposed to high temperatures (reservoir temperature). Particularly for cementing, where I dedicated most of my time, expansion has to be carefully designed not to damage the properties of the cement. If done correctly, cement expansion can even inhibit the formation of microannulus.
Our findings were recently published in a chapter in the Elsevier Reference Module in Materials Science and Materials Engineering. These studies are still very incipient, but the low weight combined with tailorable properties and ease of process makes the material applications very promising.

In my latest publication I explored the likelihood of failure in the cement sheath based on cement evaluation logs. These logs can point out heterogeneous features in the cement, such as microannulus and channels, and I can replicate these features in mechanical models. One issue that I came across is that, in many wells, these tools are not ran. To overcome this limitation I have been generating synthetic logs based on data from wells in the same field; the study was presented at the 55th US Rock Mechanics / Geomechanics Symposium. The utilization of  synthetic logs (or pseudo logs) is quite common in petrophysics and reservoir characterization to address lack of data. But unlike these logs, in cement bond logs (CBL) there is no correlation between depth or reservoir parameters and the cement bond. For this reason we chose not to use classical machine learning, where we look for the “best guess”, and employed a Bayesian approach. We used Gaussian Process Regression where, from the training data, the algorithm compute predictive distributions for new test inputs. With this framework I cannot locate the exact location of potential failure, but can quantify uncertainty in the model and exploit this uncertainty in order to make predictions on new wells. Certainly more precise than a simply random placement of cement properties.

Last month the International Energy Agency (IEA) released “Net Zero by 2050: A Roadmap for the Global Energy Sector”, a comprehensive study to lay out a cost-effective transition to a net-zero energy system while ensuring stable and affordable energy supplies, providing universal energy access, and enabling economic growth. The study laid out more than 400 milestones to reach this goal, which can translate in lots interesting research topics for us. Most of the milestones are based on policies and regulations though, but that does not mean they are less dependent on research and development. The report highlights the importance to tackle methane emissions that occur during operations and how the involvement of the oil and gas industry is critical for the acceleration of carbon capture, utilization and storage (CCSU) and hydrogen fuel (about 40% of hydrogen production comes from natural gas). You can check out the complete report here.

Last month I had the opportunity to attend a virtual workshop on Well Integrity hosted by NETL, where the research needs for subsurface energy infrastructure were discussed. There were  a series of interesting talks from international experts from academia, industry, and national laboratories over 3 days.

In the past years, the trend has been towards green energy and data-driven studies and in this event it was no different. Experimental and modelling studies on challenging environments, such as geothermal, as well as CO2 storage and hydrogen storage were presented. I am not very familiar with hydrogen storage but it makes sense, like most green energy it needs to be stored and underground storage offers a large-scale and long-term solution. There were great discussions on the importance of applying advanced analytics and artificial intelligence to get insights from open databases. It is advised to be careful using these databases since most wells have been sitting for a long time. And finally, talks on future developments moving forward, plugging and abandonment, how to better monitor methane leakages and ensure long-term integrity of wells.

Overall, it was a great opportunity to connect with experts and learn more about the current trends in well integrity. Thank you NETL for organizing this important event.

My aim with this blog is to present my research, the person behind the scientist and the overall perspectives of my past and ongoing projects. I hope you find what you are looking for, otherwise don’t hesitate to contact me. Enjoy!