Designing Drilling Mud for Stability in Shale Reservoirs: Summary & Review of ‘Mud Design for Shale Stability: More Than Just Mud Weight’ by Jovie Yunara

     This is a quick summary and review of a LinkedIn post by Jovie Yunara, a drilling operations and engineering professional. It pertains to drilling mud design for shale reservoirs to optimize wellbore stability during drilling. I remember spending a lot of time at well sites during the early part of drilling horizontal wells in shale reservoirs and the problems encountered with wellbore stability, especially with water-based muds. Oil-based mud systems are used in most shale plays and offer better well stability. However, some plays utilize new and improved water-based muds.

     A 2024 paper in Unconventional Resources by Chang Hong Gao notes that oil-based mud (OBM):

“…provides effective shale stability, excellent lubricity, and high rate of penetration (ROP). As a result, more than 70 % of shale gas wells have been drilled with OBM with very few reported cases of wellbore instability. WBM (water-based mud) is made of water and necessary chemical additives. WBM is less costly and more environment-friendly than OBM, however some shale wells drilled with WBM reported severe instability issues. Nevertheless, recent innovations in WBM lead to successes in drilling major shale plays. WBM has great potential in shale drilling and deserves more research and improvements.

     Water-based mud is more environmentally friendly and can be cheaper. I would assume that Yunara’s LinkedIn post is addressing shale drilling via OBM.

     Yunara argues in his post that mud weight alone has been overused as a solution to wellbore stability in shales. While he acknowledges the importance of optimizing mud weight, he also stresses the importance of two other parameters: mudcake integrity and chemical compatibility.  

     An effective mudcake provides a barrier to the invasion of drilling fluids into the formation, which compromises wellbore stability. As mud pressure penetrates into the shale, the possibility of shear failure and borehole instability increase due to near-wellbore pore pressure increases.

     Shale contains reactive clay minerals, which create risks for hydration and swelling of the rock. These can make the shale less cohesive, increasing the risk of failure and wellbore instability.

     Increasing mud weight has been the traditional way to increase wellbore stability. However, if the mudcake has already been compromised, then increasing the mud weight may also increase penetration into the shale. Thus, he concludes that higher mud weight does not always mean improved wellbore stability. Of course, in some formations with high bottomhole pressure, it may not be possible to increase the mud weight without effectively hydraulically fracturing the rock on a small scale, which creates even more severe well stability problems.

“The objective should be to identify a mud-weight window that maintains mechanical stability while minimizing pressure invasion and chemical weakening.”

     The figure below illustrates Yunara’s arguments about the three parameters affecting wellbore stability in shales.

References:

 

Mud Design for Shale Stability: More Than Just Mud Weight. Jovie Yunara. LinkedIn. October 27, 2026. Post | LinkedIn

Drilling fluids for shale fields: Case studies and lessons learnt. Chang Hong Gao. Sci Engine. Unconventional Resources. Volume 4. December 1, 2023. Drilling fluids for shale fields: Case studies and lessons learnt

 

 

 

                                              

Can Closed-Loop Geothermal Provide Baseload Energy? Eavor’s Recent Problems Suggest That It Cannot: Eavor Cites Hydraulic Communication Due to Inadequate Cement Jobs and First-of-a-Kind Project Economics as Challenges in Germany

      As I have noted on this blog, many people, including the realist (seemingly pessimistic) Art Berman, have long seen closed-loop geothermal as overhyped. While it may have a small role to play in the energy transition, the technology is likely limited by physics from gaining a larger role.

     Eavor is the originator of the Eavorloop, its own closed-loop advanced geothermal system. One of its first pilot commercial projects, its well-hyped Geretsried geothermal project in Germany, has faced limitations not adequately foreseen. Eavor also cancelled its upcoming project in Hannover, in Northern Germany.

     Closed-loop geothermal is a type of conduction geothermal where the fluids convey heat to a working fluid via conduction. In contrast, convection geothermal involves producing hot fluids directly to run steam turbines. Many in the industry have long noted the limitations of conduction geothermal. It is simply harder to make the economics work for conduction geothermal.

     GeoExPro’s Henk Kombrink interviewed Eavor’s CEO Mark Fitzgerald in May. Kombrink had previously been critical of Eavor’s level of secrecy about the Geretsried project and its unexpectedly low output of its first loop, expected to be at 2 MWe, but only measured at 0.5 MWe. Fitzgerald was hired as CEO in October 2025. He said he wanted the company to be more transparent. He also explained that they stepped away from being the operator of the Geretsried project and wanted to focus instead on being a technology provider. He believes another company more experienced at operating projects should take the helm as operator. As part of this change of strategy, they also reduced their team from 147 to about 80. Kombrink notes some details about why the output is so low. It was due to clogging with cuttings and unexpected communication between loops. Poor cement jobs were implicated. The output should be as designed if all the loops were drilled and functional.

“…it is already widely known that the company only completed six loops instead of the planned twelve. What was new to me was that it is actually 3 to 4 loops that are contributing to flow. Two loops experienced clogging by rock fragments to such an extent that the cleaning operation could not alleviate the problem. The third loop is only contributing to a limited extent.”

“We believe that we have proven the concept. We now have to prove commerciality,” is what he reiterated a few times during the conversation.

     The company reported in mid-October that the two drilling rigs at Geretsried had been released. Kombrink noted in the interview that the company had burned through its funding of about 350 Euros for the project. He is also not quite sure they could say they had proven the concept, given the problems.

     Think GeoEnergy reported then:

“Although the milestone validated many technical aspects of Eavor’s closed-loop concept, challenges in execution prevented the project from reaching its operational targets. A few months after the start of electricity supply, the company disclosed that the Geretsried site only achieved between 0.5 to 2.0 MWe of gross power generation, with practically no power delivered to the grid.”

“Isar Loisach Naturwärme (ILN), the district heating company founded by Stadtwerke Geretsried, expressed disappointment that the project has been further delayed.”

     They signed a heat offtake agreement for district heating in 2024, but the lack of heat due to the low number of loops and now incorrect sizing of components, including the ORC system, presents operational issues.

     In a late October article in GeoExPro, Kombrink expressed more doubts about Eavor’s failed project in Germany and its concept in general. Lack of circulation and fluid loss problems would have to be fully solved before the concept could work as designed. One of the big problems with closed-loop geothermal and Eavor’s concept in particular is that drilling and cementing wells, laterals, and sidetracks is expensive as well as technically challenging. He expressed doubt that they will find an operator willing to proceed with the rest of the Geretsried project. Kombrink expressed doubt about Eavor’s viability going forward after the clear project failure. He thinks it may be years or even decades before closed-loop geothermal becomes viable, if ever.

     Back in May of 2026, Eavor did provide a technical update on the Geretsried project on its website. The early part of the drilling encountered severe problems, which they later improved, as recounted below:

Extreme drilling dynamics and dysfunction

“The combination of deep hard rock, long laterals, high friction, and difficult hole conditions created severe shocks, vibration, and torque dysfunction. This did not just slow rate of penetration; it also damaged tools, shortened bit life, and increased trips out of hole. As the campaign progressed, we improved the bit and BHA design, adjusted drilling parameters, changed the fluid system, improved lubricity and hole cleaning, and used drilling dynamics mitigation tools. Those changes translated into better ROP, longer bit runs, and fewer drilling dysfunction issues in the later wells. Ultimately, we were able to drill the last lateral pair in a single run from each rig.”

     Bit life improved, ROP improved, and Eavor’s magnetic ranging technology, used to connect the two wellbores in the loops, proved to be successful and faster than other magnetic ranging efforts. 

  As they recount below, the biggest problem by far was hydraulic communication:

“Hydraulic communication between the two rigs through previously drilled lateral pairs”

“This challenge was by far the most impactful. Following the sidetracking of the second lateral pair, hydraulic communication (fluid flow) between the two rigs was measured. The root cause was poor cement jobs on both cased “motherbores”, enabling a significant annular fluid channel behind the casing, which connected all the lateral pairs to each other. Fluid could freely flow down previously drilled laterals and up to the other rig.”

“Efficient Eavor-Loop construction depends on two rigs drilling in parallel; each lateral pair is drilled by two rigs simultaneously and intersected, starting with the lowermost lateral and then repeating from the “bottom up”. Each previously drilled lateral pair is supposed to be sealed (hydraulically isolated) from the next lateral pair which is drilled uphole (in the direction towards the surface within the cased motherbores). However, inadequate isolation in the cement behind the casing created hydraulic communication between the two well systems/rigs. Once that happened, pressure, mud, and cuttings could move freely between the inlet and outlet patterns through previously drilled lateral pairs.”

     Below are the company’s loop models.

     Eavor also points out that compared to other EGS geothermal projects and other forms of energy, it is heavily weighted toward Capex. One of its advantages is the low Opex once a project is completed as designed and online. However, completing a project as designed is currently the biggest challenge.

     Until these technical challenges are overcome, the concept will remain uncommercialized. They believe they can commercialize and stress that Gertsried is a first-of-a-kind (FOAK) project with FOAK problems that can be overcome in subsequent testing. However, with the lackluster results and loss of capital, Geretsried can only be seen as a technical and economic failure at present.

 

 

References:

 

The end of Eavor? With the rigs having departed from Geretsried and the Hannover project cancelled, what remains of the Eavor project pipeline? Henk Kombrink. GeoExPro. October 31, 2026. The end of Eavor? - GeoExpro

Eavor withdraws drilling rigs from the Geretsried geothermal project site in Germany. Carlo Cariaga. Think GeoEnergy. October 16, 2026. Eavor withdraws drilling rigs from the Geretsried geothermal project site in Germany

Eavor stepping away from operator role in Geretsried: That’s what Eavor’s CEO Mark Fitzgerald said during an exclusive interview with us that addressed the company’s recent project in Germany as well as the new strategy it has now embarked on. Henk Kombrink. May 13, 2026. Eavor stepping away from operator role in Geretsried - GeoExpro

Technical Update from Geretsried: What we built, what we learned, and what comes next. Matt Toews. Eavor. May 21, 2026. Technical Update from Geretsried: What we built, what we learned, and what comes next - Eavor

Appalachian Basin Digest Monthly Overview Highlights Data Pertinent to EQT-Range Merger

     Appalachian Basin Digest Monthly Overview, put out by Ayers Petroleum Consulting, has offered useful data and analysis for many years. The database was developed, and the digest was formerly run by now-retired Petroleum Engineer Tim Knobloch, whom I knew personally and worked with on several occasions, and colleagues. I have come to enjoy the monthly digest highlight, which may be for a region, a company, a geological formation, or, in this case, a large company merger. It always seems to offer useful information and analysis.

     This month, for the September edition, they highlight the EQT-Range merger, announced in October. Other oil & gas data analysts like NOVI Labs and its affiliate, RBN Energy, have also offered useful data about this important merger, as I noted in a previous post just last week.

     The Digest gives a map, a table of wells, well counts and formations for each company, a producing well count over time for each company, monthly gas production for each company, and monthly liquids production for each company. The last two graphs, including the graph of liquids production titled Monthly Crude Oil/Condensate Production by Operator, show that EQT gains some optionality by adding a higher percentage of liquids production than gas production compared to its own liquids-to-gas ratio.

 

References:

 

Appalachian Basin Digest Monthly Overview September 2026. Ayers Petroleum Consulting. November 2, 2026.

 

Massachusetts Governor Healy Reversed Previous Position and Now Supports Needed Gas Pipelines

      Massachusetts governor, who, as the state’s Attorney General, fully supported blocking needed gas pipelines into the state due to climate concerns, has finally faced reality and changed her position. She now supports those pipelines. According to an article in The Cool Down, she has done two things to support affordable energy: 1) she moved money from clean energy programs to support energy affordability for citizens, and 2) she explicitly offered support for an expansion of natural gas availability by asking the Trump administration to speed up approvals for the Algonquin gas pipeline project in southern Massachusetts and Rhode Island.

“In 2025 and 2024, Healey's administration used $305 million from alternative compliance payments to reduce electric bills. In October, after declaring an "energy emergency," she said the state would draw on that same fee from utility bills — money that generally supports local and state clean energy efforts — to cut heating bills by at least $129 million, The Boston Globe reported.”

     The Globe also reported that electricity prices in the state have increased by 20% over the past three years, twice the national average. In 2025, over half of the state’s grid was powered by natural gas, with renewables making up 13%, an estimated 5% of that coming from hydro.

     The Cool Down notes: 

“The Healey administration has advanced offshore wind projects, clean-grid modernization, climate-friendly building incentives, and a 2024 law meant to speed up clean energy siting and permitting as Massachusetts works toward zero emissions by 2050.”

     However, they also backed off of some mandates such as requirements for EV sales minimums and a delay of the state’s clean heat standard. Healy can so be credited with importing more Canadian hydropower. 

     Former CNX Gas CEO Nick Deliululiis, a self-described “advocate for domestic energy and Appalachia,” and a MAGA conservative, had some commentary with which I mostly agree, since I have been tooting the same horn for about a decade. Below are some snippets from a LinkedIn post by Deliululiis. The only part I would take issue with is the part in the second snippet that wind output is limited in the winter. As I have read, wind output can be excellent in the winter in the North Atlantic, and that the few offshore wind farms online had already helped New York with its winter reliability assurance last winter, not long after they came online.

     The Cool Down article also offered two other opinions, one by an MIT economics professor and the other by a Sierra Club leader. The first response was pragmatic but also supportive of a slower energy transition. I would call that a sensible approach. The second predictably suggests Healy is a traitor to the cause and features predictable anti-fossil fuel terminology.

“Catherine Wolfram, an MIT energy economics professor and former Biden administration official, said more gas capacity could help address winter shortages, while redirected funds may provide immediate help to consumers. "Clean energy will help us break the dependence on these volatile fossil fuels, but it's going to take a while for clean energy projects to get built and for relief to show up," she told the Globe.”

“Vick Mohanka, who leads the Sierra Club's Massachusetts chapter, said of Healey: "When she came into office, she saw things the way we did — that it's an investment in an outdated and polluting, dirty system that's also expensive. And now she's asking for more pipelines."

     Mohanka is not wrong about fossil energy affordability threats. In addition to the diesel issue, the region's heavy reliance on fuel oil, which should be abandoned and replaced with cleaner, cheaper, and secure domestic natural gas, is estimated to strongly affect this winter's heating affordability.   

References:

 

Massachusetts governor backs $300 million gas expansion after earlier pipeline opposition. Leigh Cook. The Cool Down. October 30, 2026. Massachusetts governor backs $300 million gas expansion after earlier pipeline opposition

LinkedIn Post by Nick Deiululiis. October 29, 2026. Post | LinkedIn

 

Collective Human Metabolism Emits 2 Billion Metric Tons of CO2 Per Year: New Research Suggests That It Amounts to Nearly 5% of What is Emitted by Fossil Fuels and Land Use: However, It Does Not Really Add to Atmospheric CO2

       I've occasionally wondered whether scientists have ever measured the CO2 emitted by Earth’s 8 billion-plus humans, what percentage it is of the total, and how it compares to fossil fuel emissions. It turns out, according to new research published in Lancet Planetary Health, that human metabolism produces about 2 billion metric tons of CO per year, nearly 5% of what is produced by fossil fuels and land use combined. However, by itself, human metabolism contributes very little to climate change since much of that CO2 would have been emitted to the atmosphere via decomposition.   

     The modeling study, led by the University of Bath, tabulated CO2 emissions from human metabolism from 1985-2015. They found that the amount of carbon emitted increased by 74% through that time period, getting up to 2.05 billion tons per year.

     The CO2 emitted by humans comes from the food we eat, mostly from plants and animals that eat plants. We convert the food to energy and exhale CO2 as part of the metabolic process. The CO2 we release would likely be released to the atmosphere anyway as it decomposes, but likely a bit slower. Thus, I would conjecture that human metabolism is not really carbon-neutral, at least in the near-term, but closer to it long-term.  

     According to Phys.org:

“The study found that the amount of CO₂ produced by people worldwide rose from 1.18 billion metric tons in 1985 to 2.05 billion metric tons in 2015. Population growth accounted for more than 60% of the increase.”

     The study involved measuring how much CO2 we release at different ages, from infancy to old age. They also utilized global population data and body weight data to arrive at their conclusions. They concluded that less of the increase was due to per capita CO2 emissions increases and most was due to population increases. It should be noted that per capita CO2 emissions have been dropping in developed countries for many years now but are still increasing in developing countries. Theoretically, when those countries become fully developed, their per capita emissions will go down. However, they will likely continue to rise until then as those countries continue to electrify, adopt portable fossil fuels like LPG to replace wood and charcoal, and industrialize. 

     The authors explain the study, previous studies, and the implications below:

     According to Javier Gonzalez, one of the paper’s authors:

“The important thing is that the carbon dioxide we breathe out is not the same as burning fossil fuels. We're not saying that breathing is driving climate change.”

"What this study does is give us a much clearer picture of how much CO₂ people produce around the world, and how that is changing as the population grows. This understanding can help improve the accuracy of predictions of carbon reduction programs."

 

References:

 

Collective human metabolism produces 2 billion metric tons of CO₂ a year, global study estimates. University of Bath. edited by Lisa Lock, reviewed by Robert Egan. Phys.org. November 1, 2026. Collective human metabolism produces 2 billion metric tons of CO₂ a year, global study estimates

Accounting for global carbon dioxide production from human metabolism between 1985 and 2015: a modelling study. Javier T Gonzalez, Lorenzo Lolli, Bruno Spellanzon, Greg Atkinson, Ed Maunder, Alfonso Moreno-Cabañas, Jariya Buniam, Dylan Thompson, and James Betts. The Lancet. Planetary Health. October 26, 2026. Accounting for global carbon dioxide production from human metabolism between 1985 and 2015: a modelling study - The Lancet Planetary Health

Tesla Discontinues Solar Roof Tiles Due to Poor Economic Performance: Apparently, the Hype Was Miles Away from the Reality

     I remember when Tesla’s solar roof tiles, made to look and act like roof shingles, were all the rage, promising to be a way to replace your roof and add rooftop solar at the same time, in one step, which seemed to be an economical way to re-roof. However, the seemingly practical solution did not stand up to the hype. Tesla now admits that the roof tiles are not an economical solution and has discontinued them. It adds to the renewable energy hype vs. reality argument, with another point for reality. The peak hype for the tiles happened in the late 2010s.

     Tesla discontinued selling its roof tiles in August 2026, after determining that the product was no longer economically viable. Of course, the loss of rooftop solar subsidies via the Trump administration likely put the last nail in the coffin. However, problems with the roof tiles were apparent before that, as Tesla stopped advertising and actively marketing them in 2024. As noted below by Electrek, the solar roof tiles were a big part of Tesla’s pitch after buying debt-laden SolarCity in 2016.

“The Solar Roof was never just a product. It was a pitch.”

“Elon Musk unveiled it in October 2016 on a Hollywood back lot, using homes from the set of Desperate Housewives fitted with the tiles. Weeks later, Tesla shareholders voted to approve the company’s roughly $2.6 billion acquisition of SolarCity — a debt-laden solar installer where Musk was the largest shareholder and chairman, and which was run by his cousins.”

     The roof tiles were a central part of selling the SolarCity deal to investors. Apparently, the roof tiles at that time were not yet even functional. The reality was far worse than the hype depicted and suggests that Elon Musk is not the genius he was hyped as either, unless one includes bilking consumers as genius. He is still able to spend $500 million on our latest nationwide election with his (ill-gotten?) gains.

“Years later, during shareholder litigation over the acquisition, it emerged that the tiles shown at the 2016 event were not yet functioning solar products.”

“The original promise was compelling: Tesla marketed the Solar Roof as costing less than a new conventional roof plus traditional solar panels combined, with early quotes in the neighborhood of $22 per square foot.”

“Reality diverged sharply. Installed prices came in far higher than the initial figures — and, for many customers, far higher than the quotes Tesla itself had provided. In 2021, Tesla drastically increased Solar Roof prices, in some cases after customers had already signed contracts.”

“That triggered a class-action lawsuit that Tesla settled for $6 million in 2023. One customer’s contracted price reportedly jumped from about $72,000 to roughly $146,000 before installation.”

“Musk repeatedly said Tesla would be producing and installing 1,000 Solar Roofs per week — a target he pinned to the end of 2019 and the first half of 2020. When Tesla claimed it had reached 1,000 roofs of weekly production in 2020, installations lagged far behind.”

“At its peak, Tesla was installing roughly 21 to 32 Solar Roofs per week, according to Wood Mackenzie data — more than 95% short of the goal. In total, the firm estimated Tesla installed only about 3,000 Solar Roof systems in the US across roughly seven years. As we’ve been tracking the widening gap between the Solar Roof’s promise and its reality, the product quietly slid toward irrelevance.”

     In other words, the solar roof tiles were a massive economic failure, with hype that was very unfair to the consumers bilked into buying them, complete with estimates that were far different from the actuals. It’s something that sounded good and practical on paper but failed miserably in the real world. Of course, Tesla still sells solar panels, but not solar roof tiles. It adds to the list of Musk’s hyped-up failures, which are substantial. However, those failures, which would have been grounds for getting fired in some cases, did not prevent him from becoming a trillionaire and the richest man in the world.

     The top comment on the Electek articles by Spec9 sums up the failure:

“It was inevitable. Just another overhyped failure. Bad thermal issues, too expensive to install, niche market, difficult & expensive to repair, etc.”

     According to an article in Yahoo:

“The shingles required special glass tiles instead of standard solar panels, which needed custom equipment to make. The higher manufacturing cost was not offset by customer demand.”

“The system was also hard to install, costly to service, and had long wait times for repairs. Some customers even reported temperature control issues, likely due to reduced airflow compared with rack-mounted panels. Still others claim prices ended up much higher than expected, with quotes allegedly increasing by up to 100% after signing a Solar Roof contract. This culminated in a class action lawsuit that Tesla settled in 2023.”

     Basically, it was a bad marketing decision by Musk, who has argued that his expertise was allocating funds, and that is why he deserves to be super rich.

     The tiles hit mass production in 2020, and by 2021 the cost overruns and other problems were apparent. Hoping for 1000 installations per week, the product was installed less than 1000 times per year. Oops!

 

 

 

References:

 

Tesla discontinues its Solar Roof tiles, not economically viable. Fred Lambert. Electrek. August 20, 2026. Tesla discontinues its Solar Roof tiles, not economically viable | Electrek

Tesla Stops Selling Solar Roof Tiles, Refocuses on Regular Solar Panels. Devesh Beri. Yahoo. August 24, 2026. Tesla Stops Selling Solar Roof Tiles, Refocuses on Regular Solar Panels

Tesla is ditching its solar roof tiles for a good reason: Tesla had to cut losses after significant mistakes and overspending. Antony Terence. November 1, 2026. Tesla Is Ditching Its Solar Roof Tiles For A Good Reason