Some Geological and Soils Free Mobile App Reviews: Rockd, Soil Web, and Soil Explorer

 

Rockd

     This one is really great. Basically, it is a surficial geological map of the entire earth, both continental and maritime. It can be laid over a map layer with countries, states, and provinces and also a satellite map layer, both with on-off switches. Zooming in you can see individual faults. The detail is great. You can put a pin anywhere and it will give you the surface formation name and age in both geologic age and in years ago. You also get a stratigraphic name, description, comments, lithology, and references. The references are linked to scientific papers. Some are just abstracts but many are full papers. The dashboard is nice but only records data for your present location including formation name, age, lithology, lat/lon, and elevation. Tabs include a really neat paleogeography function where you can see your continental position on a paleo map of the continent and oceans as they were then. You can toggle it back from modern (which here is late Pleistocene showing glacial extent) to 750 mya well into the Precambrian. For more detail there is a pull-down menu which you can click on intervals of 5-10 my until you get into the Precambrian where there are only three choices covering 150 my. Three maps are given: one of the whole world, one of the continent, and the local scales at the time. Even paleo lat/lon coordinates are given so you can see where the plate(s)/continent was at the time. This would be fantastic for doing paleo-reconstruction, tectonic event sequencing, depositional, and erosional studies. Another tab shows minerals at your site, including metamorphic minerals and accessory minerals as well as a list of minerals groups. All have chemical formulas, type, color, descriptions, and references. A similar tab is there for fossils that shows name, phylum, class, order, extant, global occurrences, age range, localities, and nearby collections, distance from occurrences, nearby taxa, and stratigraphy, and links to more information. There is even a Brunton compass which utilizes your phone’s motion sensors! You can save your strike/dip and/or trend/plunge measurements with standard deviations. They do mention that the phone’s gyroscope requires calibration and that electrical currents, metals, and metallic minerals in rocks can introduce errors. In the tutorial it says you can tilt and rotate the map to get an oblique view of the landscape, which is new in version 3, although I haven’t figured out how to do that yet. Finally, you can check-in at different places, record your trips, set up a profile, and share and view others’ check-ins. This app is great fun for a geologist as well as anyone studying geology or just interested in geology. Fantastico! I believe the paleogeography part was developed by the developer of GPlates, another app, which I hope to review as well.

   

Rockd: Location-Specific Sample Info

Rocked: example along Allegheny Front in Central Pennsylvania showing geologic map and mapped faults. 

 

SoilWeb

     This app allows querying USDA-NRCS soil survey data. It was developed by the California Soil Resource Lab at UC Davis in collaboration with the USDA-NRCS. You can get soil data at your location with series and horizons within the series with color charts. Details for each series include map unit data and survey metadata. There is also a detailed description of each series and its horizons. Taxonomic class, typical pedon, and type locations are given for each series. Range in characteristics of the series and its horizons are detailed and competing series, geographic setting, geographically associated soils, drainage and saturated hydraulic conductivity, use and vegetation, distribution and extent, other data, and remarks are also given. Another tab gives soil taxonomy, soil properties on a graph for each property, land classification, hydraulic and erosion ratings, forest productivity, and soil suitability ratings. You can also link to UC Davis soil maps over ESRI map layers to see the series extent.

 

Soil Web: Site-Specific Example

Soil Explorer

     This is a great app for soil scientists. It is global but offers more detail in the U.S. where soils are well mapped. Detailed maps are loaded for 16 U.S. states. The global map includes color maps of soil order, soil moisture regimes, and soil temperature regimes. The soil orders tab gives information about a particular soil order when you click over a region. The global map: “is based on a reclassification of the FAO-UNESCO Soil Map of the World (FAO/UNESCO, 1972 - 1981) combined with a soil climate map. It is the same as the Global Soil Regions map published by the USDA/NRCS (Reich and Eswaren, 2005).” There is a map soil order and draft maps of duric-calcic-gypsic-salic horizons and deep sandy soils for the entire U.S. There are also detailed maps for Kenya and Peru. The detailed maps of 16 U.S. states include: Dominant Soil Parent Materials, Soil Orders, Natural Soil Drainage Classes, Aquic Conditions, Dark-Colored Surface Horizons, Clay-Enriched Subsoils, Leached Acid Subsoils, Calcic Horizons, Swelling Soils, Sodic Soils, Fragipans, Hillshade. Aerial Imagery (USGS) and Topography (USGS Topo) layers are included.

Soil Explorer: Example: Soil Orders Map of Southeastern Ohio

Links:

Rockd. rockd

Soil Web. SoilWeb: An Online Soil Survey Browser | California Soil Resource Lab (ucdavis.edu)

Soil Explorer. Soil Explorer

 

 

Grid-Scale Solar Underperformance is Significant: What are the Issues?

 

     Capex for utility-scale solar had been dropping steadily until 2022 when those costs rose for the first time in decades. In mid-2022 insurance provider kWh Analytics did a cost-analysis in that year’s Solar Risk Assessment report. They concluded that grid-scale solar remains plagued by underperformance issues. Performance remains below expectations. According to Liam Stoker of PV Tech, the assessment: “cites new research confirming that system degradation, inverter availability and overly-optimistic PV modelling have meant that the solar industry has “significantly overestimated” expectations of solar assets and, as a result, will need to “reckon the realities in the field with the assumptions we use on paper”. Along with those issues, other issues were analyzed that contribute to local and regional solar underperformance, including topography and uneven terrain (up to 6% performance losses) and extreme weather events such as hail and wildfire smoke. Wildfire smoke led to as much as 3% annual soil–related performance losses at solar PV sites in California between 2018 and 2020. Operational risks include inverter performance and inverter service support problems. Overall, the study identified by far the largest underperformance issue as financial modeling risk, which is routinely overly optimistic. kWh noted: “92% of lost EBITDA is due to underproduction, dwarfing all other sources of risk.”

    In the same report, Solargis, a solar resource data company, recently analyzed “annual global horizontal irradiation (“GHI”) compared to long-term averages, finding significant resource variability in North America over a period of 23 years from 1999 to 2021.” They concluded that annual solar irradiation is 10% below long-term averages in several U.S. regions.

     One problem with inverters contributing to operational risk is inverters abandoned by manufacturers who discontinue models and go out of business. Solar operation & maintenance company Solar Support noted in the same report that solar facilities with discontinued inverters from manufacturers no longer in business perform at an average of 85% technical availability whereas the industry standard goal is 97-99% power plant availability. Grid solar operator NovaSource, also in the same report, reported that inverters were underperforming compared to expectations during their 2-year warranty period. They concluded that inverters underperformed by 40% during the 2-year warranty period. NovaSource found average inverter failure incidences at about 1 per year per inverter (0.8-1.4 times /year). That is not a large problem by itself, but one must also calculate mean-time-to-repair (MTTR) in order to evaluate effects on technical availability. Again, and surprisingly, inverters under warranty performed worse and required more time to repair. Suggested strategies for improving the problems include better inverter testing before large deployment, developing an inventory of standardized parts and expertise to speed up repair times, and enabling O&M companies to perform some repairs to decrease down time.

     Underperformance from uneven terrain that increases shading can be addressed with more advanced tracking and better modeling. DNV calculated up to 6% of losses from uneven terrain, much of which can be reduced.  

     There are some other issues that lead to underperformance such as Balance of System anomalies associated mostly with large and complex systems. String anomalies were the most common, but inverter, combiner, module, and tracker anomalies also affect performance. Digital Analytics company Raptor Maps, in the same report, concluded that these types of anomalies led to 2.63% underperformance in 2021, up from 1.85% in 2020.

     Basic system degradation results in efficiency losses that the NREL calculates at an average of 0.75% per year. This is based on 4915 inverters being analyzed and with a total of more than 7.2 GW under observation monitoring for long-term performance.

     Manufacturing changes can affect system degradation. In solar module manufacturing, doping with gallium instead of boron has improved the problem of destabilization but has also led to faster degradation. This will require more research, says PV Evolution Labs, also part of the study.

     Current ongoing supply chain issues can also have negative effects on quality control/quality assurance. Better inspection, testing, and further QC/QA may be needed.

     Analytics company UL Solutions noted that the recent study concludes that solar underperformance compared to pre-construction estimates is at 6.3% on average and that 3-4% of that lost energy is recoverable as the problems that lead to it are addressable. UL Solutions provides monitoring, production key performance indicators (KPIs), analytics, and reporting.

     The kWh solar assessment report also showed that actual production vs. P50 estimates have been getting further apart in recent years despite improvements in module and system efficiencies through the years. A December 2022 article in PV Tech by Jonathan Touriño Jacobo notes: “… the underperformance trend remains a nationwide issue with average lifetime performance ranging from 5-10% below initial P50 estimates across the US, with the exception in 2021 of the Northwest and Southeast regions which improved by 1% and 2%, respectively.”

  U.S. Solar Installations: Source: Bloomberg NEF. Note: Capacity reported in direct current (DC) terms.

 

References:  

US solar remains beset by underperformance issues as capex costs on the rise. Liam Stoker. PV Tech. June 14, 2022. US solar remains beset by underperformance issues as capex costs on the rise - PV Tech (pv-tech.org)

Analytics and expertise to assess, optimize and report on operational performance. UL Solutions (website). 2023. Operational Performance Assessment For Solar Assets | UL Solutions

US solar assets ‘are not meeting performance expectations’, kWh Analytics says. Jonathan Touriño Jacobo. PV Tech. December 7, 2022. US solar assets ‘are not meeting performance expectations’, kWh Analytics says (pv-tech.org)

Solar Risk Assessment: 2022: Quantitative Insights from the Industry Experts. kWh Analytics. Solar Risk Assessment: 2022 Quantitative Insights from the Industry Experts (squarespace.com)

New Natural Hydrogen Discovery Announced in The Lorraine Mining Basin in Eastern France

 

     French low carbon energy company FDE announced a new natural hydrogen discovery in the Lorraine mining basin in Eastern France. The presence of natural hydrogen was known in the basin but new measurements in an old test well in the basin have confirmed a high purity percentage of natural hydrogen at depth. I did a deep dive into natural hydrogen on this blog a few months ago which can be read here. The Lorraine Mining Basin has produced both iron ore and coal in the past.

     The natural hydrogen is dissolved in a Carboniferous aquifer. The new measurements at the  Folschviller well site were done in collaboration with the University of Lorraine and the CNRS, France’s National Center for Scientific Research. Researchers reported “a measured concentration of 15% at 1,093-meter depth and estimated at 98% at 3,000-meter depth.” The deeper high purity hydrogen is likely a significant find. There are several different mechanisms for H2 outgassing and many involve continuous natural production of the gas. FDE has submitted an application for an exclusive mining permit to explore for natural hydrogen that covers an area of 2,254 km², in the Grand-Est region. The prospective area is the hydrogen ecosystem of the Greater Region (Grand Est, Wallonia, Luxembourg, Sarre, and Rhineland-Palatinate). Thus, parts of Germany and Luxembourg are also prospective. A planned 100% H2 cross-border pipeline being commissioned to pass through the area can provide for transport of the gas. The next step in the project is to select a site for a pilot drilling project. 

     Some of those same researchers from the University of Lorraine and the CNRS in a paper in October 2016 proposed a new interpretation of the Lorraine-Saar Basin of France and Germany as “a thin-skinned asymmetrical parallelogram-shaped pull-apart basin.” Extensional basins have been associated with H2 outgassing but I am unsure of the H2 generation mechanism here. The basin is bounded on the north and west by the Metz fault which parallels the basin. There are also associated wrench faults which have influenced deposition after reactivation.

     

Structural Features and Sedimentation in the Lorraine-Saar Coal Basin France-Germany. Source: A NEW TECTONIC MODEL FOR THE LATE PALEOZOIC EVOLUTION OF THE LORRAINE-SAAR COAL-BEARING BASIN (FRANCE/GERMANY. Vitaliy Pryvalov, Jacques Pironon, Alain Izart, Raymond Michels, Olena Panova. October 2016. VitaliyPryvalov1.pdf

References

FDE Discovers Natural Hydrogen in Eastern France. Pipeline and Gas Journal. May 16, 2023. FDE Discovers Natural Hydrogen in Eastern France | Pipeline and Gas Journal (pgjonline.com)

Natural Hydrogen: Exploring for H2 Through the Drillbit: Reserves and Economic Estimations. Kent C. Stewart. Blue Dragon Energy Blog 2.0. March, 27, 2023. Blue Dragon Energy Blog 2.0: Natural Hydrogen: Exploring for H2 Through the Drillbit: Reserves and Economic Estimations (bdeb2.blogspot.com)

A NEW TECTONIC MODEL FOR THE LATE PALEOZOIC EVOLUTION OF THE LORRAINE-SAAR COAL-BEARING BASIN (FRANCE/GERMANY. Vitaliy Pryvalov, Jacques Pironon, Alain Izart, Raymond Michels, Olena Panova. October 2016. VitaliyPryvalov1.pdf

Climate Defiance: What is the Real Level of Support for Hardcore Climate Activism and What Motivates It?

 

     Outlandish anti-fossil fuel activism in Europe is an occasional thing and sometimes in bad taste like the recent vandalism of valuable works of art. In the U.S. we have development of “direct action” protests. They are touted as non-violent but can involve blockades. One group, Climate Defiance, for a planned blockade of the White House Correspondents Dinner had a stated goal of “aiming to blockade in such large numbers that arrests will be impossible.” I don’t know their metrics or level of active support, but I am quite skeptical of it being that high. On their website is the pledge to “Make support for any fossil fuels as unacceptable on the left as opposing abortion or gay marriage.” Apparently, their effort failed to attract enough media attention to make headlines afterward. They claim to have been part of the voting block that helped to elect Biden, who they now charge with ‘ecocide’ by approving the Willow Project to drill for oil in Alaska. Their main slogan seems to be End Fossil Fuels, not unlike the Keep It in the Ground Movement. In their protest they chanted “No more drilling!” But did such groups really add much to Biden’s victory? I doubt it. Do most Democrats support them? I doubt it. I would guess just a minority, 20% at most or hopefully and more likely much less. My guess is about 5-10%. However, even a vocal minority can be influential. As do other such groups, they try to equate climate justice with racial justice and economic justice. There is probably a little more support for hardcore activism in Europe where groups like Just Stop Oil and Extinction Rebellion are active. Groups like Bill McKibben’s 350.org seem to be a little quieter than they have been in the past.

     With companies addressing ESG concerns and with likely permit reforms that will and should weaken the power of mainstream environmental groups to block energy and infrastructure projects, it might be interesting to see how the radical groups react. Such groups and their supporters no doubt had a hand in New York’s recent bans on natural gas in new buildings and in California which is also considering such bans. Biden has proved to be more pragmatic and more problematic for hardcore activist groups than they had hoped, although he still seems beholden to the views of some of those groups. His reckless rhetoric during his campaign about ending fossil fuels may have given them false hope but hopefully wiser and more moderate voices have toned down that tendency. The realities of the need for reliable and affordable energy in light of significant energy cost increases in 2022 no doubt caused a reassessment of priorities. Biden has repeated the often-repeated incorrect claim that solar and wind are the cheapest forms of energy.  

     The Climate Defiance group also held a protest of a Biden Campaign Fundraising Dinner in New York City. Speakers included Jane Fonda and Steven Donziger. Fonda spoke of the need to go further with activism, whatever that really means.

     A couple of newish terms suggest what motivates climate activists. One I’ve been seeing more and more is ‘climate crisis deniers.’ This extends the slight (originating from Holocaust deniers) from those who reject prevailing climate science and those who simply downplay the dangers. Many IPCC scientists would be included as climate crisis deniers or climate emergency deniers. The science of climate change is suggestive but not settled. Needed policy is even further from being clear cut. True believer fanatics attacking more moderate thinkers with slogans and provocative terms and phrases is common among radical groups. Climate apocalypticism is alive and well. In an important sense it functions similarly to a doomsday religious cult. Repent or perish! Another term I’ve been hearing about for a few years is ‘climate anxiety’ or ‘climate distress.’ I wrote about this in my first book, Sensible Decarbonization. More recently I heard a psychiatrist on NPR, who advised climate lawsuits filed by youths, talking about it. The assessment in my book is that it can be a real phenomenon but that it is primarily fueled by activists, those in academia in cahoots with activists, and by media amplification of the doomsday message. The psychiatrist talked about it being very bad among youth and that she herself had to be prescribed anti-anxiety medicines because of her climate anxiety! Really? I would say that such doomsday mental conditioning is more dangerous than climate change. How climate change will happen is not very predictable at present, just more likelihoods of potentially dangerous events. It is not the type of danger one can specifically prepare for with the very notable exception of vulnerable areas preparing for extreme weather events, that may be influenced by climate change. Risk perception is a major factor in how people react to threats and often there is a gap between perceived risk and real risk. This gap is influenced by many factors, including media amplification and the brain’s coping mechanisms.      

    

References:

Climate activists plan to 'blockade' White House Correspondents Dinner, accuse Biden of 'ecocide'. Adam Sabes. Fox News. April 29, 2023. Climate activists plan to 'blockade' White House Correspondents Dinner, accuse Biden of 'ecocide' (msn.com)

Climate Defiance (website). Climate Defiance

Climate Defiance Joined by Steven Donziger, Jane Fonda to Protest Biden Fundraising Dinner. Democracy Now. May 11, 2023. Climate Defiance Joined by Steven Donziger, Jane Fonda to Protest Biden Fundraising Dinner | Democracy Now!

Risk Assessment, Risk Management, and Risk Perception. Kent Stewart. Blue Dragon Energy Blog 2.0. Blue Dragon Energy Blog 2.0: Risk Assessment, Risk Management, and Risk Perception (bdeb2.blogspot.com)

Upper Cretaceous Eagle Ford Shale and Austin Chalk Oil & Gas Plays in the Western Gulf Coast Basin in South Texas

 

Geology and Resource Assessments

     The Eagle Ford Shale Play in South Texas is one of the biggest U.S. shale plays. Just above the Eagle Ford is the Austin Chalk, a 100-600ft thick zone of chalk and marl (carbonate-rich mudstone). There are also multiple layers of volcanic ash from a series of submarine volcanoes that were active when the chalk was deposited. They are associated with the Laramide orogeny. Chalk is a type of soft, white, porous limestone composed mainly of calcite and originally formed deep under the sea by the compression of microscopic plankton that had settled to the sea floor. The Austin Chalk is primarily composed of microscopic shell fragments from floating sea organisms known as "coccolithophores" (the same organisms that contributed to the White Cliffs of Dover, on the south coast of England). The Austin Chalk is a tight argillaceous limestone, a brittle carbonate with vertical fracturing that allowed oil and gas to migrate up from its source in the Eagle Ford, which is the next formation below it. Sometimes it is recrystallized. It has been producing oil and gas for a hundred years, with several successful revitalizations as extraction technologies and geological understanding improved. The chalk is porous with matrix porosity ranging up to 10% but permeability is low. It is a brittle rock that tends to fracture. Early wells in the play, including early horizontal wells were not hydraulically fractured but produced from natural fractures. Some wells were phenomenally productive but were required to access fractures, later typically identified on seismic lines. According to a December 2021 paper in Marine and Petroleum Geology about matrix reservoir quality in the Austin Chalk by Robert Loucks and Sheng Peng: “The depositional environment of the chalk is interpreted to have been a deeper-water (below storm wave base) setting on a drowned shelf where bottom waters and sediments varied between oxic and anoxic.”

Upper Cretaceous Stratigraphy in South and East Texas

     According to an October 2018 article in American Oil & Gas Reporter: “According to a newly revised U.S. Geological Survey assessment, undiscovered and technically recoverable Eagle Ford resources are pegged at 8.5 billion barrels of oil, 66 trillion cubic feet of natural gas, and 1.9 billion barrels of natural gas liquids. It has been a while since USGS assessed the Austin Chalk, but it has estimated 900 million barrels of oil in only the Giddings Field, the play’s largest field, spanning parts of seven counties in South-Central Texas, which already has produced 526 million barrels of oil and 4.7 Tcf of gas.” No doubt, the Austin Chalk reserves will exceed the early USGS reserves assessment.

     The Eagle Ford can be thick where produced and wells can be drilled and spaced in the Upper Eagle Ford and Lower Eagle Ford. According to a 2014 EIA assessment: “The formation is divided into two units: an upper unit, characterized by interlayered light and dark gray calcareous mudrock deposited during a regressive interval (sea level falling), and a lower unit of mostly dark gray mudstone deposited during a transgressive interval (from rises in sea levels).” Depths to reach the Eagle Ford vary from about 6500 ft in Southwest Texas to over 11,000 ft in productive areas in Southeast Texas to over 17,000 ft further south into the basin where it is less likely to be developed due to those depths and leaking seals. Depths to the Austin Chalk are similar being just above the Eagle Ford but the chalk wells in Louisiana can be quite deep at over 14,000 ft. The Eagle Ford is one of the four big shale oil plays in the U.S. as well as a significant gas play. The continuous gas deposit in the Eagle Ford and Austin Chalk is downdip from the continuous oil deposit due to thermal maturity dynamics. The deeper gas window is favorably situated near U.S. LNG export terminals on the Southeast coast of Texas. The Eagle Ford and Austin Chalk trends no doubt extend into Mexico from Southwest Texas.

Eagle Ford Hydrocarbon Fairways

Eagle Ford-Austin Chalk Hydrocarbon System Play Concept

     A 2021 case study of the Lower Eagle Ford to determine key geological factors controlling estimated ultimate recovery (EUR) of wells concluded that the four major factors are: reservoir capacity, resources, flow capacity, and fracability. Total porosity and hydrocarbon-bearing porosity directly determine reservoir storage capacity but total organic content (TOC) and vitrinite reflectance are indirect determinants. The resources of shale hydrocarbons are determined by hydrocarbon-bearing porosity and effective shale thickness. Flow capacity is controlled by effective permeability, crude oil density, gas-oil ratio, condensate oil-gas ratio, formation pressure gradient, and R₀. Fracability is controlled directly by brittleness index and indirectly controlled by clay content in volume.

Geological Factors Affecting EURs, Source: Quantitative assessment of the sweet spot in marine shale oil and gas based on geology, engineering, and economics: A case study from the Eagle Ford Shale, USA. Energy Strategy Reviews. Volume 38, November 2021, 100713. Lianhua Hou, Caineng Zou, Zhichao Yu, Xia Luo, Songtao Wu, Zhongying Zhao, Senhu Lin, Zhi Yang, Lijun Zhang, Dingwei Wen, Jingwei Cui. Quantitative assessment of the sweet spot in marine shale oil and gas based on geology, engineering, and economics: A case study from the Eagle Ford Shale, USA - ScienceDirect

Eagle Ford Sweet Spot Reservoir Analysis. Source: Quantitative assessment of the sweet spot in marine shale oil and gas based on geology, engineering, and economics: A case study from the Eagle Ford Shale, USA. Energy Strategy Reviews. Volume 38, November 2021, 100713. Lianhua Hou, Caineng Zou, Zhichao Yu, Xia Luo, Songtao Wu, Zhongying Zhao, Senhu Lin, Zhi Yang, Lijun Zhang, Dingwei Wen, Jingwei Cui. Quantitative assessment of the sweet spot in marine shale oil and gas based on geology, engineering, and economics: A case study from the Eagle Ford Shale, USA - ScienceDirect 

     The Eagle Ford thins to the north and does not thicken into the East Texas Basin like the rocks below it. Its productive fairway and hydrocarbon windows are well established. The shale extends into northern Mexico and is very prospective there as is likely the Austin Chalk. Shale gas and oil reserves analysis suggests that Mexican shale gas (545 Tcf) is the 6th largest such gas resource in the world, most of which is in the Eagle Ford. The Burgos Basin in Mexico, a southern extension of the Western Gulf Basin of South Texas is a main area of prospectivity. Development has been slow in Mexico hampered by government issues and early poor results, but the hydrocarbons are there and should be comparable to the high reserves just across the border.

 

Gen 1: Austin Chalk Natural Fracture Porosity Play

     Traditionally, Austin Chalk wells were drilled to access gas and oil filled natural fractures. In the late 1980’s the Austin Chalk began to be explored more resulting in some large vertical wells although there were also many dry holes. It was hit or miss. Seismically identified fractures and small faults were the targets. The play reached from South Texas into South-Central Louisiana where it is deeper. With the advent of horizontal well drilling in the 1990’s it was postulated that these lateral wells could access more of these vertical fractures and thus more oil and gas reserves, and this turned out to be true. There were also fewer dry holes. The legacy fracture porosity drilling trend is generally just slightly up-dip from the more recent matrix porosity trend. The early active parts of the play were towards Central Texas. The Giddings Field there is the largest Austin Chalk fracture porosity field developed.  

 

Gen 2: Austin Chalk in Early Horizontal Drilling, High-Volume Hydraulic Fracturing, and Geosteering

     The Austin Chalk was one of the first widely successful horizontal gas plays and initial production in these wells often exceeded 50MMCF/day in-line. It was once thought that the source rock of Austin Chalk was the organic carbon in the chalk itself but later it was realized that the Eagle Ford shale was the source rock. The Austin Chalk horizontals led to a more integrated horizontal drilling industry with the development of logging-while-drilling (LWD) or measurement-while-drilling (MWD) with gamma ray logging tools and to geosteering wells with that gamma ray. By the mid-1990’s new companies like Horizontal Solutions International (HSI) emerged that were devoted to geosteering horizontal wells. The new horizontals in the chalk also spurred George Mitchell and Mitchell Energy to test the Barnett Shale with horizontal drilling and high-volume hydraulic fracturing in the 90’s which led to new shale gas plays like the Marcellus, Fayetteville, and Haynesville Shales which would be followed by new horizontal oil plays from shales in the Bakken, Eagle Ford, Niobrara, and in the Permian shales of West Texas. Other horizontal plays like the Bossier Limestone which sits above the Haynesville Shale were developed in Northeast Texas in the early 2000’s and are now being successfully revisited today. The wells targeting fractures only were not hydraulically fractured but produced naturally with some huge wells. This is a huge cost savings over wells that need to be fracked.

    

Gen 3: The Austin Chalk Matrix Porosity Play

     In the mid-2010’s some companies began exploring the Austin Chalk away from the highly fractured areas, instead targeting the higher matrix porosity zones in less fractured areas. The results were very good. Importantly, they were more repeatable than in the fractured play where results were often inconsistent. New 3D seismic data also showed more fractures that were untapped so that in some areas both matrix and fracture porosity can be targeted. This happened in the Giddings Field where there were multiple 20-30 BCF wells in the 1990’s that were produced naturally without fracs. Areas with over 6% matrix porosity are targeted to be fracked and have been showing very good results. The Giddings Field had been assumed to be depleted but new wells have shown strong results and good long-term performance targeting matrix porosity. Wells have responded well to increased proppant loading with the goal of producing from the induced fractures. Thus, results are more consistent than wells targeting natural fractures. Wells have responded very well to Eagle Ford style fracs. Clay-control chemicals have also been helpful in increasing connectivity and preventing the volcanic ash from sealing fractures. Operators have also noted that determining permeability and calculating water saturation in the play can be tricky. Determining storage capacity in a mixed lithology fractured limestone can also be tricky. Fortunately, results have often been better than predicted.

     Robert Loucks and Sheng Peng in 2021 identified five lithofacies in the Austin Chalk that positively affect reservoir quality. Here they mention the most important 4 of them: “Burrowed marly chalk (lithofacies 1) has the best reservoir quality, with a mean porosity of 6.2% and a geometric mean permeability of 351 nd. Burrowed chalky marl to marly chalk (lithofacies 2) has the second-best reservoir quality, with mean porosity being 5.5% and geometric mean permeability being 214 nd. Slightly burrowed laminated marly chalk (lithofacies 3) has a mean porosity of 4.5% and a geometric mean permeability of 101 nd. Well-laminated chalky marl to marly chalk (lithofacies 4) has the poorest reservoir quality, with a mean porosity of 3.5% and geometric mean permeability of 25 nd.”

  

Revival in Austin Chalk Production Beginning in mid-2010's. Source: Austin Chalk Revival: New Oil and Gas from an Old Trend. (2018?). Austin Chalk RevivalAustin Chalk Revival (austinchalkoilgas.com)

 

Troughs or Sub-Basins with Thick Rock Sections and High Reserves

     The Karnes Trough area has a thickened Lower Cretaceous section of dolomitic limestones which includes locally slightly thicker Austin Chalk and Eagle Ford. From 2015 Austin Chalk production increased from about 24 MBOPD and 200 MMCFGPD to about 75 MBOPD and 320 MMCFGPD by the end of 2017. This is mainly attributed to new chalk wells in the trough and platform/monocline areas of Karnes County, Texas. The Maverick Basin in Maverick and Dimmit Counties in South-Southwest Texas is another area of thickened Eagle Ford that is continuing development in Dimmit County. Here the drilling depths are shallower which helps with well costs. It is mainly the Austin Chalk and the Upper Eagle Ford that are thickened in the Maverick Basin. EOG’s Dorado discovery in nearby but deeper Webb County has been described as a sub-basin. Successful very high reserve wells have been drilled here over the last few years.

 

Austin Chalk, Eagle Ford, Buda Combo Plays

     The Eagle Ford prospective fairway is large, and the Austin Chalk prospective fairway overlaps it in many counties from East-Central Texas to South-Southwest Texas. The Buda Limestone, a dolomitic limestone, lies below the Eagle Ford. It is developed as a fractured carbonate reservoir in a few areas overlapping Austin Chalk and Eagle Ford. Other combo plays include formations just above the Austin Chalk, the San Miguel and the Olmos, to the west in the Rio Grande Embayment area. The Hearne area in the northern part of the play in Burleson, Milam, and Robertson Counties is prospective in the Austin Chalk, Eagle Ford, and Buda. This area is up on the platform where the production is oil. In that area some of the nearby older wells have also experienced increased production as a result of fracking of new wells.

 

EOG’s Dorado Discovery Area

     In November 2020 EOG Resources unveiled their Dorado discovery in Webb County, Texas in an area of thick Austin Chalk (~400ft) and thick Eagle Ford (~ 300ft) with high reserve potential. In their 163,000 net acres they estimated gas reserves of 21 TCF from 1250 potential net locations in both formations, 9.5 TCF in the Austin Chalk from 530 locations and 11.5 TCF in the Eagle Ford from 720 locations.  In the past few years, they have been drilling the area successfully but have recently in 2023 decided to temporarily defer completing 2023 wells due to low gas prices, leaving them as DUCs. EOG drilled 17 Austin Chalk wells in Dorado in 2019 then paused drilling in 2020 to evaluate production while analyzing the field with cores, petrophysical logs, and 3D seismic. According to EOG’s E.V.P. of Exploration and Production, Ken Boedeker from a February 2021 article in American Oil & Gas Reporter: “With a break-even cost of less than $1.25 per Mcf, we believe this play represents the lowest cost supply of natural gas in the United States. At Henry Hub prices of $2.50 per Mcf, Dorado competes directly with our premium oil plays. We are leveraging our proprietary knowledge built from prior plays to move quickly down the cost curve with our initial development. We currently estimate a finding cost of $0.39 per Mcf in the Austin Chalk and $0.41 per Mcf in the Eagle Ford.” Following a year of production, by early 2021, EOG became confident in their reservoir model and reserves estimates and I believe drilled another 15 wells in the field that year. The play also benefits from abundant infrastructure availability with access to LNG export terminals, pipelines selling to Mexico, and local sales points. It also gives EOG optionality when oil prices are low and gas prices are more favorable.

 

Austin Chalk Exploration Failures in East Louisiana and Mississippi: Deep, Expensive, and Often Wet

     The Austin Chalk has also had some success in Western Louisiana with some developed fields and several periods of waxing and waning interest there and to the east. EOG made a discovery further east in 2017 and drilled about 6 wells I believe but by Sept. 2019 decided to abandon the area due to increased water production. Another of the downsides is that it is deeper there. EOG, Marathon, Conoco Phillips, and others made a run for acreage and drilled test wells in Eastern Louisiana and Mississippi but poor results and water seem to be an insurmountable problem so most companies have pulled out. While the Eagle Ford Shale is below the Austin Chalk in Texas, another source rock, the Tuscaloosa Marine Shale (TMS) is below the chalk in Louisiana and Mississippi. Australian company Australis Oil and Gas drilled some very deep 15,000 -20,000 ft wells in the TMS in 2019 that were pretty good wells, but the TMS has been challenging as a whole with the play all but abandoned. The company does worry about rapid decline which they have seen in the Austin Chalk wells in the area, and which is known in the low permeability TMS.  

 

Drilling Issues in the Austin Chalk and Eagle Ford

     The presence of some small offsetting faults and fractures combined with high formation pressures and possible interference from nearby wells has led to some drilling issues in both formations. Lost circulation and mud loss can be issues. Managed pressure drilling, including drilling on mudcap with no cuttings returning to the surface is not uncommon in some areas. Differential sticking, when the drill string sticks to the side of the well bore can occur when pressures drop away from the wellbore due to intersecting open fractures. These South Texas plays are also deep, with high pressures and fairly high temperatures, which can contribute to variations in well bore integrity. The Eagle Ford drills fast like most shales. The Austin Chalk drills a little slower than the Eagle Ford but still pretty fast. Small faults can complicate geosteering in some areas. The volcanic ash layers can also be hazardous as they fall in and as they have a tendency to keep the bit in them if drilled horizontally close to formation dip. That also results in more ash in the cuttings and a higher potential for plugging fractures. Thus, wells may be steered away from the known ash layers.

 The Eaglebine: The Woodbine Sandstone and the Eagle Ford non-calcareous Mudstone Play in the East Texas Basin

     The Eaglebine is a name given to the combo play of Eagle Ford and Woodbine formations in the East Texas Basin. The north and east of the main Eagle Ford fairway in the Western Gulf Coast Basin is bounded by the San Marcos Arch. On the northeast side of the arch is the East Texas Basin where these rock formations again thicken but have different facies and lithologies. The Eagle Ford is mainly the upper Eagle Ford equivalent and is less calcareous than in the main producing area and less prospective. However, below the Eagle Ford is the Woodbine Sandstone which is a major oil and gas producer in the East Texas Basin at depths greater than 12,000 ft. The Woodbine is age equivalent to the Tuscaloosa Marine Shale (TMS) further East beyond the Sabin Uplift which bounds the East Texas Basin to its northeast. The Woodbine organic shale below the sands is also an important target at shallower depths The Lower Eagle Ford intertongues with the Maness Shale and the Pepper Shale that underlies the Eagle Ford in South Texas intertongues with the Woodbine Sandstone. The Woodbine facies include incised valley fills to the northeast and fluvial-deltaic sandstones to the southwest. These reservoirs as such can be more heterogenous and reservoir quality can be more difficult to predict and less consistent for horizontal drilling. Still, production has been very good in some of these zones, with EURs sometimes exceeding 30-40 BCF in vertical wells but with wells nearby having much lower production. The Woodbine is “highly stratified and diagenetically complex.” The history of cement diagenesis is thought to be a key factor in preserving porosity and corresponding high hydrocarbon production. These are monster wells but with drilling depths up to 15,000 ft they are also costly.

Eaglebine Play Regional Stratigraphy. Source:Stratigraphic and Depositional Context of the Eaglebine Play: Upper Cretaceous Woodbine and Eagle Ford Groups, Southwestern East Texas Basin. Tucker F. Hentz and William A. Ambrose. AAPG. Search and Discovery Article #51094. June 22, 2015. View PDF (searchanddiscovery.com)

Woodbine Reservoir and Diagenesis. Source: Woodbine Formation Sandstone Reservoir Prediction and Variability, Polk and Tyler Counties, Texas. Robert J. Bunge. AAPG. Search and Discovery Article #10331. June 25, 2011. Woodbine Formation Sandstone Reservoir Prediction and Variability, Polk and Tyler Counties, Texas; #10331 (2011) (searchanddiscovery.com)

References: 

Austin Chalk Revival: New Oil and Gas from an Old Trend. (2018?). Austin Chalk RevivalAustin Chalk Revival (austinchalkoilgas.com)

East Texas Chalk: It’s The Matrix. Nissa Darbonne. Oil and Gas Investor. Hart Energy. January 24, 2020. East Texas Chalk: It’s The Matrix | Hart Energy

Austin Chalk Revived: An Emerging Unconventional Play. Laurentian Research. March 7, 2019. Seeking Alpha. Austin Chalk Revived: An Emerging Unconventional Play | Seeking Alpha

The Eagle Ford and Austin Chalk: Better Operating Practices and New Approaches Keep South Texas Humming. Al Pickett. American Oil and Gas Reporter. October 2018. Better Operating Practices And New Approaches Keep South Texas Humming (aogr.com)

Matrix reservoir quality of the Upper Cretaceous Austin Chalk Group and evaluation of reservoir-quality analysis methods; northern onshore Gulf of Mexico, U.S.A. Robert G. Loucks and Sheng Peng. Marine and Petroleum Geology. Volume 134, December 2021. Matrix reservoir quality of the Upper Cretaceous Austin Chalk Group and evaluation of reservoir-quality analysis methods; northern onshore Gulf of Mexico, U.S.A. - ScienceDirect

Louisiana Austin Chalk: Hundreds of Millions Down the Drain? Matt Zbrowski. Journal of Petroleum Technology. September 29, 2019. Louisiana Austin Chalk: Hundreds of Millions Down the Drain? (spe.org)

Haynesville, TMS and the Austin Chalk: Louisiana’s place in the Lower 48 supply stack. Brandon Myers. Wood Mackenzie. January 2020. General template rules (planoweb.org)

Quiet for decades, Austin Chalk oil and gas play attracting new interest. Mark Passwaters. S&P Global Market Intelligence. June 8, 2018. Quiet for decades, Austin Chalk oil and gas play attracting new interest | S&P Global Market Intelligence (spglobal.com)

Key geological factors controlling the estimated ultimate recovery of shale oil and gas: A case study of the Eagle Ford shale, Gulf Coast Basin, USA. Lianhua Hou, Zhichao Yu, and Senhu Lin. June 2021. Petroleum Exploration and Development 48(3):762-774. (PDF) Key geological factors controlling the estimated ultimate recovery of shale oil and gas: A case study of the Eagle Ford shale, Gulf Coast Basin, USA (researchgate.net)

Quantitative assessment of the sweet spot in marine shale oil and gas based on geology, engineering, and economics: A case study from the Eagle Ford Shale, USA. Energy Strategy Reviews. Volume 38, November 2021, 100713. Lianhua Hou, Caineng Zou, Zhichao Yu, Xia Luo, Songtao Wu, Zhongying Zhao, Senhu Lin, Zhi Yang, Lijun Zhang, Dingwei Wen, Jingwei Cui. Quantitative assessment of the sweet spot in marine shale oil and gas based on geology, engineering, and economics: A case study from the Eagle Ford Shale, USA - ScienceDirect

Eagle Ford Shale play economics: U.S. versus Mexico. Ruud Weijermars, Nadav Sorek, Deepthi Sen, Walter B. Ayers. Journal of Natural Gas Science and Engineering. Volume 38, February 2017, Pages 345-372. Eagle Ford Shale play economics: U.S. versus Mexico - ScienceDirect

Woodbine Formation Sandstone Reservoir Prediction and Variability, Polk and Tyler Counties, Texas. Robert J. Bunge. AAPG. Search and Discovery Article #10331. June 25, 2011. Woodbine Formation Sandstone Reservoir Prediction and Variability, Polk and Tyler Counties, Texas; #10331 (2011) (searchanddiscovery.com)

Stratigraphic and Depositional Context of the Eaglebine Play: Upper Cretaceous Woodbine and Eagle Ford Groups, Southwestern East Texas Basin. Tucker F. Hentz and William A. Ambrose. AAPG. Search and Discovery Article #51094. June 22, 2015. View PDF (searchanddiscovery.com)