Geological Theory Research Articles

Improved pore structure prediction based on a stacking machine learning model for low-permeability reservoir in Tazhong area, Tarim Basin

Stacking is an ensemble machine learning method designed to improve overall performance by combining the predictions of multiple base learners. The core idea of Stacking is to use the output of different base learners as input and make final predictions through a meta-learner, allowing the model to benefit from the strengths of various base learners and adapt better to complex data patterns. Predicting pore structures in low permeability is a sophisticated nonlinear modeling issue affected by multiple factors, including sedimentary and diagenetic effects on the structure. An individual model to predict pore structure is not satisfactory. In this paper, we applied a fusion of random forest and Adaboost models as base learners, which emerges as the cornerstone of this research, showcasing remarkable versatility and integration of diverse learner strengths. The Silurian system in Tazhong area features a vast expanse of lithological reservoirs with low abundance and high heterogeneity. Capillary pressure plays a crucial role in the distribution of these less permeable reservoirs by pore structure type influence. Aiming to predict the pore structure for the low-permeability reservoir in the field, which is characterized by low abundance and high heterogeneity, the study strategically integrates geological theory into specialized databases and harnesses machine learning methods. The resulting machine learning modeling dataset leverages geological factors and logging response characteristics to strengthen the ensemble machine learning stacking model. This sophisticated model not only achieves exceptional accuracy but also undergoes rigorous validation by analyzing predicted pore structure types alongside production data. The model's average accuracy was 79.4%, which practically hit the test set's accuracy threshold, meaning that the model was in an optimal state. In essence, the proficiency of the stacking model in predicting pore structure types serves as a transformative force, offering significant advancements in hydrocarbon distribution predictions and paving the way for more streamlined and effective future EOR activities.

Whole petroleum system in Jurassic coal measures of Taibei Sag in Tuha Basin, NW China

Based on the latest results of near-source exploration in the Middle and Lower Jurassic of the Tuha Basin, a new understanding of the source rocks, reservoir conditions, and source-reservoir-cap rock combinations of the Jurassic Shuixigou Group in the Taibei Sag is established using the concept of the whole petroleum system, and the coal-measure whole petroleum system is analyzed thoroughly. The results are obtained in three aspects. First, the coal-measure source rocks of the Badaowan Formation and Xishanyao Formation and the argillaceous source rocks of the Sangonghe Formation in the Shuixigou Group exhibit the characteristics of long-term hydrocarbon generation, multiple hydrocarbon generation peaks, and simultaneous oil and gas generation, providing sufficient oil and gas sources for the whole petroleum system in the Jurassic coal-bearing basin. Second, multi-phase shallow braided river delta–shallow lacustrine deposits contribute multiple types of reservoirs, e.g. sandstone, tight sandstone, shale and coal rock, in slope and depression areas, providing effective storage space for the petroleum reservoir formation in coal-measure strata. Third, three phases of hydrocarbon charging and structural evolution, as well as effective configuration of multiple types of reservoirs, result in the sequential accumulation of conventional-unconventional hydrocarbons. From high structural positions to depression, there are conventional structural and structural-lithological reservoirs far from the source, low-saturation structural-lithological reservoirs near the source, and tight sandstone gas, coal rock gas and shale oil accumulations within the source. Typically, the tight sandstone gas and coal rock gas are the key options for further exploration, and the shale oil and gas in the depression area is worth of more attention. The new understanding of the whole petroleum system in the coal measures could further enrich and improve the geological theory of the whole petroleum system, and provide new ideas for the overall exploration of oil and gas resources in the Tuha Basin.

THEORIES OF THE EARTH AND ‘PLUTONISM’ IN THE INTRODUZIONE ALLA GEOLOGIA BY THE ITALIAN GEOLOGIST SCIPIONE BREISLAK (1811)

ABSTRACT Scipione Breislak may be considered as one of the most renowned Italian ‘Plutonists’ at the end of the eighteenth and beginning of the nineteenth centuries. In the 1790s, he was a professor of Physics at the Military Academy of Nunziatella in Naples, where he also devoted himself to the study of Vesuvius and the Phlegraean Fields. Thus, he acquainted himself with volcanic phenomena. Breislak's works about the volcanic fields of Campania (Southern Italy) disclosed how Torbern Olof Bergman's theories and Antoine-Laurent de Lavoisier's chemistry had affected his belief in the idea that volcanic eruptions were triggered by ignition of petroleum deposits. After a voluntary exile in France, owing to the downfall of the Roman Republic, Breislak returned to Italy and settled in Milan, where he was appointed as an Inspector of Gunpowder in 1802. Due to his new administrative duties, he had the opportunity to continue studying mineralogy and geology, focusing primarily on the stratigraphy of Lombardy and of the Alps. During the ‘Milanese period’, he published the Introduzione alla geologia (Introduction to geology, 1811), which may be regarded as the first Italian handbook about the ‘new’ science of Geology. In the monograph, he also drew on Huttonian ideas in order to describe the lithostratigraphic features of crystalline rocks. Without neglecting Breislak's volcanological hypotheses, this paper aims to analyze the influence that nineteenth-century Plutonist (Huttonian) geological theories had on the Earth's history that he depicted in the Introduzione alla geologia. The influence of Plutonism—a term that Richard Kirwan introduced to define James Hutton's geological system—may also be recognized in Breislak's rejection of transition rocks. Indeed, according to him: “nature does not make passages or transitions, and each of its products has a specific and particular way to exist” (Breislak 1811, volume 1, pp. 308–309).

Heat flow in the Eurasian, North American and Atlantic regions

The article is a presentation of the research results of the next stage of complex geophysical control of models of deep processes in the tectonosphere of continents and oceans, built by geological theory. Models of the crust and upper mantle are located along a system of profiles encircling the northern hemisphere of the Earth, which have are DSS sections (in some places fragmentary, especially in the oceans). In the first stage, control was performed for density models. It is shown that the gravitational field can always be explained without fitting by calculated effects with discrepancies corresponding to the errors. The second stage focused on thermal models, the effects of which were compared with the observed heat flow (HF) distribution through the surface. Solving the problem is complicated by many features of the manifestation of a nonstationary thermal field. Some of them can be considered as nearsurface interference that needs to be eliminated (but usually this is not done). The work done covered the regions of Eurasia and North America, the Atlantic Ocean, a peripheral fragment of the Pacific Ocean, and transition zones between continents and oceans. Activated and nonactivated platforms, Phanerozoic geosynclines, and rifts were studied on the continents. In transition zones, there are depressions with recent oceanisation, island arcs, and deep9sea trenches. In the oceans, there are basins and the mid9ocean ridge (MOR). In the MOR and some other areas of the World Ocean, the intensity of interference does not allow the use of observed HF for routine monitoring. In other regions, the result was achieved, although often after smoothing out the heat flow field. On the continents, the cases are better, although there are also situations where significant parts of the profiles should simply be excluded from consideration due to an unacceptable level of error. However, here it was possible to confidently demonstrate the correspondence of thermal models of deep processes to experimental HF within the limits of observation and calculation errors.

Letters of Johann Jacob Ferber Geological descriptions of Slovenia from second half of 18th century

The two translations of letters by Johann Jacob Ferber (1743–1790), a Swedish geologist and mineralogist, who travelled through Slovenia in September 1771, are discussed. The first letter addressed to Ignaz von Born was published in the book »Briefe aus Wälschland über natürliche Merkwürdigkeiten dieses Landes an den Herausgeber derselben Ignatz Edlen von Born« published in Prague in 1773, and the second letter to Giovanni Arduino was published in the book »Raccolta di memorie chimico-mineralogiche, metallurgiche, e orittografiche« published in Venice in 1775. Both letters represent an Enlightenment scientific description of the geology of part of what is now Slovenia, based on the geological theories valid at the time. In the article, we provide brief biographies of the actors, translations of the two letters, their commentary and interpretation.

Microbial coalbed gas and its geological formation process in the Jimsar region of the southern Junggar Basin, NW China

The southern Junggar Basin is abundant in coalbed gas (CBG) resources, with the Jimsar region in the southern part of the basin emerging as a potential CBG development demonstration area. However, further development of the CBG in this region is restricted by the lack of understanding of the genesis and gas reservoir formation mechanisms of the CBG. This study systematically collected CBG samples and associated water samples from the Jimsar region. Stable isotope, hydrogeochemical, and 16S ribosomal ribonucleic acid (rRNA) sequencing studies were carried out. The results demonstrate that the CBG is the primary microbial gas, and CO2 reduction is its formation pathway. Hydrogeochemical analysis shows that the coalbed water receives recharge from meteoric or surface water. The water environment is relatively active (open system). The total dissolved organic carbon (TDOC) in the coalbed water is primarily from coal, and the supply and consumption of the total dissolved nitrogen (TDN) may be relatively balanced. The dissolution of CO2 is the main source of the dissolved inorganic carbon (DIC). Furthermore, the positive δ13CDIC values and high alkalinity indicate microbial methanogenesis. Microbial community structure analysis revealed that the archaea are hydrogenotrophic methanogens in the Jimsar region. The microbial basis for the production of microbial gas is provided by the existence of hydrolytic, acidogenic, and hydrogen-producing acetogenic bacteria as well as methanogenic archaea. Natural gas genetic identification diagrams and detection of methane-oxidizing bacteria (Methylomicrobium) reveal that the CBG may be affected by slight oxidation. In addition, the methanogenic effect is much greater than the methane oxidation. Finally, based on these results and the regional tectonic background, the CBG enrichment and accumulation mode in the Jimsar region was established. This mode can be divided into three geological stages: burial and coalification, surface water recharge and microbial gas generation after uplift and denudation, and CBG accumulation controlled by reverse faults and hydrodynamic sealing. This study enriches the geological theory of CBG accumulation in the Jimsar region and provides guidance for the subsequent exploration and development of the CBG.

Pore Water and Its Multiple Controlling Effects on Natural Gas Enrichment of the Quaternary Shale in Qaidam Basin, China

Quaternary shale gas resources are abundant in the world, but Quaternary shale contains a lot of pore water, which affects the enrichment of shale gas. At present, the controlling effect of pore water on gas enrichment in Quaternary shale is not clear. Taking the Quaternary shale of Qaidam Basin, China as an example, this paper systematically studies the characteristics of pore water in Quaternary shale through X-ray diffraction rock analysis, nuclear magnetic resonance, methane isothermal adsorption and other experiments, and reveals the controlling effect of pore water on shale gas enrichment. The results show that clay shale and silty shale are mainly developed in Quaternary shale. The clay shale is more hydrophilic, and water mainly exists in micropores and mesopores. Silty shale is less hydrophilic, and water mainly exists in mesopores and macropores. Pore water controls the formation of shale gas by the content of potassium and sodium ions, controls the adsorption of shale gas by occupying the adsorption point on the pore surface, controls the flow of shale gas by occupying the pore space, and controls the occurrence of shale gas by forming water film. Therefore, pore water has multiple controlling effects on shale gas enrichment. This achievement is significant in enriching shale gas geological theory and guide shale gas exploration.

Genesis, Distribution, and Characterization of a Paleokarst Subsurface River System in the Tahe Area, Tarim Basin, Western China

Summary Subsurface river systems constitute one of three major paleokarst types that make up Ordovician reservoirs in the Tahe area of the Tarim Basin. The total length of the river system is approximately 400 km, and the reserves associated with this karst type are more than 200 million tons. However, it is manifested that 47% of drilled wells have not encountered river paleokarst, while 50% of wells that have encountered river paleokarst are fully filled due to the poor understanding of the paleokarst of this region, resulting in a significant variation of production capacities. In this study, we propose a detailed data integration approach with outcrops, drilling, logging, seismic profiles, and dynamic data to delineate the complex paleokarst river system in the Tahe area. The karst geological theory with reservoir characterization is combined in particular. The workflow of clarifying the main controlling factors, architecture types, and development distribution modes of the subsurface river system is established. Fill material type, sequence of fill structure, and fill controlling factors are also revealed. A quantitative characterization method of the subsurface rivers is established adopting predictions based on seismic data and high-resolution geostatistical and geological modeling. The Ordovician reservoirs in the Tahe area comprise three paleokarst river systems with different characteristics. Karst paleogeomorphology is the main control over the overall flow direction and plane distribution of the subsurface rivers. Changes in the surface of the phreatic zone are crucial in controlling the vertical layers and scale of the rivers. The combined action of faults plays a decisive role in controlling the anastomosing pattern of the rivers. Single-branch channels, reticulated channels, and structural corridors in single-layer or multilayer styles are the main subsurface river types. Trunk channels, branch channels, hall caves, and inlets/outlets are dominant structures in the architecture of the river system. Sand-mud, breccia, and chemically precipitated materials are the most common fill types. Three typical sequences of fill structure and four spatial combination modes exist in the subsurface river system. The morphology and fill characteristics of rivers are predictable using seismic attributes, such as frequency division energy, frequency division inversion, and coherent energy gradient. 3D models are constructed by multivariate control multipoint geostatistical method, which can characterize the strong heterogeneity characteristics of subsurface river systems. This complex paleokarst system enables remarkable results for the adjustment of the reservoir development plan through quantitative characterization.

Theory, Technology and Practice of Unconventional Petroleum Geology

Theory, Technology and Practice of Unconventional Petroleum Geology

Extracting fact-condition relation from geological papers via deep structured semantic model with multi-grained representation

The fact-condition statement plays a significant role in the geological papers, where geological theory or phenomenon as a fact is constrained by its precondition. This constraint relation conveys a lot of key information in geological papers, but it has been ignored in most of studies on the information extraction. Although the rule-based algorithms have been proposed in the previous studies to extract the relationship between facts and conditions, but their low accuracy limit usability. Therefore, this paper introduces a series of mechanisms and methods to improve the extraction accuracy. We firstly utilize three kinds of pooling for extracting the semantic features of fact-condition tuples to find that balanced semantic representations can more accurately reflect their relations. In addition, semantic correlation between facts and conditions is also designed to mine their relations via the measurement of semantic similarity or semantic distance. Based on the above, the Deep Structured Semantic Model with Multi-Grained Representation (MGR-DSSM) is proposed. In this model, the Deep Structured Semantic Model (DSSM) is utilized two individual projections for denoising semantic correlation between facts and conditions, while the Multi-Grained Representation (MGR) is designed for encoding their semantic correlation at multiple granularities. Furthermore, the linear MGR-DSSM with SciBERT achieves the best result with 70.41% of accuracy and 74.55% of F1 score, obviously outperforming other baseline models. Finally, the linear MGR-DSSM with SciBERT is adopted to extract super relation from 722 geological paper abstracts, and the geological knowledge graph with fact-condition statement is built. With more accurate relation between fact and condition, the information validity of geological knowledge graph is enhanced.

Temperature distribution in the crust and upper mantle of the territory of Ukraine

The study aims to build a three-dimensional thermal model of the crust and upper mantle of the territory of Ukraine. Its basis is a scheme of deep processes in the tectonosphere, which, first of all, considers the results of heat and mass transfer during modern activation. They are superimposed on the models of the platform (except for the territory of the East European platform; the Donbas is also included in it), the Alpine geosyncline of the Carpathians, and the Hercynian-Cimmerian geosyncline of the Scythian plate. The incomplete process of modern activation cannot be accurately described by the geological theory used by the authors. Gravity modeling was previously conducted on a system of profiles around the northern hemisphere with a total length of more than 30,000 km, crossing Eurasia, North America, as well as the Atlantic and Pacific oceans to select an adequate scheme of heat and mass transfer. The paper distinguishes the most realistic scheme of the process . It is applied for Ukraine, and the more accurately the activated area is determined. Such a task was solved for the first time. In the south, the model is limited by the Black Sea depression, at a depth of 400 km. Temperatures in the transition zone to the lower mantle were not considered. Test thermal models are compared with geothermometers. The error (50°C) of calculation and cross-section of isotherms is determined (150°C for depths from 50 to 400 km, at a depth of 25 km the error is lower, the cross-section of isotherms is 100°C). Zones of partial melting of the rocks of the crust and upper mantle have been established. They are distributed in the middle part of the crust, in the upper horizons of the mantle (50-100 km). At a depth of about 400 km, partial melting occurs only under the non-activated part of the platform. Differences in the model from the presented one are described. They are associated with possible variations in the age of the process and its peculiarities at different levels of heat and mass transfer. Practical significance. The study emphasizes that mineral deposits are characteristic to thermal anomalies and other environmental parameters.

Paul Bishop and Robert Burns

ABSTRACT Attention is drawn in this brief note to how Paul Bishop’s interests as an earth scientist and physical geographer inspired the author in interpreting the poetry of Scotland’s national bard, Robert Burns. James Hutton’s geological theories regarding the age of the earth, the historical instability of the earth’s surface and the erosive powers of the elements likely influenced Burns, suggesting new inflections to the interpretation of at least two of his well-known poems. Paul Bishop’s assistance with respect to interpreting a Burns copyist’s poem is also explained.

Shale gas accumulation patterns in China

Although significant progress has been made in the geological theory and exploration and development of shale gas in China, the research on the geological particularity and enrichment regularity associated with shale gas accumulation remains weak. With this in mind, we analyzed the shale gas accumulation patterns in China. The findings show that: (1) A variety of organic-rich shales were deposited in the continental margin-type marine and transitional environments during the Pre-Mesozoic period and the basin-type terrestrial environment during the Mesozoic and Cenozoic eras. (2) The basins dominated by Mesozoic and Cenozoic terrestrial sediments superimpose on the Pre-Mesozoic continental margin-type marine–or transitional-facies sediments. The former developed the terrestrial shales with large thickness, high organic matter abundance, new age, and low thermal maturity; meanwhile, the deep parts of the basins are favorable for shale gas enrichment. However, the latter preserves the shale with old age, high thermal maturity, and undergoing multiphase tectonic movements; and the tectonically stable regions are favorable for shale gas enrichment. (3) The aulacogens mainly formed in the Meso-Neoproterozoic, Sinian-Ordovician, and Devon-Triassic periods are favorable for marine organic-rich shale deposition; moreover, this type of shale and other types including transitional facies shales with favorable reservoir-forming assemblages, coal-measure shales in small and medium-sized basins, and low-medium mature shales affected by magma intrusion, have jointly constituted the various shale gas accumulation patterns in China. (4) Based on the drilling discoveries in China, shale gas accumulation patterns can be categorized into two types: tectonic-controlled and stratigraphic-controlled. The former is mainly related to structural features, whereas the latter is mainly related to the variation of lithology and strata. (5) Shale development and gas content are mainly affected and controlled by geological factors including sedimentation, diagenesis, and later tectonic movements. Favorable sedimentary environments, appropriate thermal maturity, good sealing capacity of caprock, and excellent structural preservation are the necessary conditions for shale gas enrichment.

Exploration, development, and construction in the Fuling national shale gas demonstration area in Chongqing: Progress and prospects

In September 2013, the National Energy Administration approved the establishment of Fuling national shale gas demonstration area (hereinafter referred to as the demonstration area), whose construction was completed in December 2015. After nearly one decade of development, it has grown into the main shale gas production base in China. In order to speed up the integration and breakthrough of China's shale gas theoretical understanding and exploration and development technology and effectively promote the great development of marine shale gas in China, this paper reviews and summarizes the development and construction history of the demonstration area, geological theory understanding, engineering technology and key equipment progress. And based on this, the future development direction of the demonstration area is predicted. And the following research results are obtained. First, shale gas exploration and development in the demonstration area is divided into three stages, i.e., exploration evaluation, phase I and II construction, and stacked development and adjustment. Second, the “binary enrichment” theory for marine shale gas and the engineering theory for efficiently developing gas reservoirs are innovatively established. Third, a series of supporting technologies are innovatively developed, such as optimized and fast drilling technology for shale gas cluster horizontal wells, differentiated network fracturing technology, high-efficiency gas production, gathering and transportation technology, and green development technology for karst mountains, and the localization of key equipment and tools is realized. Fourth, the efficient development of shallow overpressure shale gas reservoirs above 3500 m in depth and the effective development of shale gas reservoirs at the depth of 3500–4000 m are realized in the demonstration area. Fifth, the construction of the demonstration area in the future includes accelerating the development of normal-pressure deep shale gas, continuously tackling key shale gas EOR technologies, actively promoting the field application of new technologies and methods, and powerfully strengthening the construction of green demonstration areas. In conclusion, this demonstration area is the earliest one of four national shale gas demonstration areas, and its achievements will provide continuous guidance for the shale gas exploration and development in China and play a demonstrative and guiding role in promoting the development of shale gas geological theories and exploration and development technologies in China.

Method and Application of Reservoir Unit Division in Continental Faulted Lacustrine Basin: An Example from the L70 Fault Block in Raoyang Sag.

The continental faulted lacustrine basin is an important type of continental oil and gas basin with typical compound oil and gas accumulation characteristics. The traditional petroleum geological theory usually makes a general analysis of multiple reservoirs. It uses the structural model to understand the reservoir and has a vague understanding of the reservoir. The actual exploration is inconsistent with the traditional theory, which restricts exploration and development. In this case, taking the lower submember of Sha 1 of Shahejie Formation of L70 fault block in Raoyang sag as an example, the concept of reservoir unit is put forward, and the reservoir is redivided using the "four diagrams and four steps" method, the oil-water distribution is clarified, the type of reservoir unit is defined, and multiple potential reservoir units are proposed. It enriches and perfects the traditional petroleum geological theory, provides a new research method and idea for petroleum exploration and development, and ushers in new opportunities for the developed old oil fields.

Deep Time: Queen Mab

ABSTRACT This essay examines Percy Bysshe Shelley's understanding and representation of Romantic–age conceptions of planetary temporalities on the scale of what we would today refer to as “deep time,” or the prehuman history of the Earth. I explore Shelley's response in Queen Mab; A Philosophical Poem: with Notes (1813) to James Hutton's geological theories of planetary temporalities and show that Shelley's depiction of eternalism in this poem must be recontextualized in light of Hutton's geological critique. Few scholars have sought to explore the deep time dimensions of the poem's intense temporal rescaling and Shelley's voluminous prose notes on the topic. As I show, Shelley's conception and representation of temporal scale in Queen Mab is likely informed by Hutton's research leading to the publication of his Theory of the Earth, with Proofs and Illustrations (1795) and the afterlife of that work in his friend and popularizer John Playfair's Illustrations of the Huttonian Theory of the Earth (1802). If we are going to unpack and comprehend Shelley's depiction of eternity in Queen Mab, we must return to the geological notion of eternalism defining Huttonian theory.

Biodegradation of early thermogenic gas and generation of secondary microbial gas in the Tieliekedong region of the northern Tarim Basin, NW China

Some important progress has been made in coalbed gas (CBG) exploration in the Kuqa-Bay coalfield in the northern Tarim Basin, where a demonstration base of CBG development and utilization has been established in the Tieliekedong (TD) region. Currently, there has been no detailed study of the formation mechanism of the CBG in the TD region, which has restricted the next phase of the CBG exploration. In this study, gas and water samples in the TD region were collected and analyzed to determine the genesis of the CBG, the formation pathways of the microbial gas, the source of the coalbed water, the composition of the microbial community, and the accumulation process of the CBG. The results indicate that the CBG in the TD region is a mixture of biodegraded thermogenic gas and secondary microbial gas. The geochemical characteristics of the water samples indicate that the coalbed water actively receives recharge from surface water, and it exhibits the characteristics of a weak-runoff water environment (i.e., a relatively closed system). Based on the stable isotope compositions of the gas-water samples, CO2 reduction is the main metabolic pathway for generating the microbial gas. That is, in the relatively closed system, initial CO2 from the different sources was converted to CH4 by hydrogenotrophic methanogens (e.g., Methanobacterium), and the residual CO2 became progressively enriched in 13C (i.e., high positive δ13C-CO2 and δ13C-dissolved inorganic carbon values). However, the microbial community composition indicates that acetogenic bacteria (e.g., Acetobacterium, and Lentimicrobium) and acetoclastic methanogens (i.e., Methanosaeta) are widely developed in the coalbed water, so acetoclastic methanogenesis should also take place. According to the priority of the biodegradation, the microbial oxidation of thermogenic C2+ components (e.g., ethane and propane) mainly occurred in the early stage and lasted for a short period of time, primarily producing CH4 enriched in 12C. After these components were consumed, the bacteria began to degrade the organic matter in the coal, and the methanogens continued to generate secondary microbial gas, finally forming a 13C-enriched pool of carbon species. Based on these results, the CBG accumulation in the TD region was determined. The results of this case study provide an obvious supplement to the geological theory of CBG accumulation, and have a guiding significance for CBG exploration in the TD region.

Differential Reservoir-Forming Mechanisms of the Lower Paleozoic Wufeng-Longmaxi and Niutitang Marine Gas Shales in Northern Guizhou Province, SW China: Theories and Models

Fine dissection of microscopic pore structure variations between the Niutitang Formation and the Wufeng-Longmaxi Formation will help to improve the understanding of the underlying geological theory of shale gas in northern Guizhou Province. The stratigraphic, geochemical, physical, and tectonic properties of the two formations vary greatly, resulting in differential development of the microscopic pore structure among reservoirs and, as a result, major variances in gas concentration. To explore the mechanism of differential pore evolution, experimental techniques and instruments such as gas adsorption, liquid intrusion, SEM, XRD, and organic geochemical tests were utilized. The results indicate that the Wufeng-Longmaxi Formation is in a high-maturity stage, while the Niutitang Formation is in an over-mature stage. The latter has a higher TOC content. Both petrographic phases are siliceous shale petrographic phases, and the former has more developed dissolution pores with better pore volume, throat radius, and macropore pore diameters than the latter, as well as organic matter pores, intergranular pores, and microfracture structural parameters, whereas the specific surface area is the opposite. The differences in reservoir pore formation between the two formations were analyzed, and the results showed that the petrographic type, thermal evolution, and tectonic preservation conditions were the primary controlling elements of differential shale gas reservoir formation. A differential reservoir-forming model of the Wufeng-Longmaxi Formation and the Niutitang Formation was constructed, providing a geological and theoretical basis for shale gas geological exploration in northern Guizhou Province.

Evaluation of Blended Learning Effect of Engineering Geology Based on Online Surveys

Engineering geology applies geological theories and methods to the practice of engineering activities, evaluates the engineering geological conditions of the engineering site through engineering geological investigation and comprehensive research of theories, solves the engineering geological problems related to engineering activities, predicts and demonstrates the occurrence and development laws of engineering geological problems in the engineering activity area, and puts forward technical measures for prevention and control, so as to contribute to the planning, design, and construction and provide necessary geological and technical data for use and maintenance. Based on the theory of multiattribute decision-making, this paper puts forward the evaluation index system of engineering geology teaching quality in applied universities. A curriculum teaching quality evaluation index system is constructed, which is composed of four main indexes: online resources and teaching, offline teaching process, classroom teaching quality evaluation, and classroom teaching quality evaluation. Furthermore, 11 second-class indices and 28 third-class indices are considered. The judgment matrices and membership degree of each attribute are obtained through use of a questionnaire, and the total weight of each subitem is calculated using the analytic hierarchy process. The calculation results show that the classroom instructional quality of the engineering geology course can be considered excellent; furthermore, other courses could also be evaluated using the same method, where those with low evaluation results can be further improved. Using the fuzzy comprehensive evaluation method based on the analytic hierarchy process, we evaluate the instructional quality, comprehensively consider the nonlinear and fuzzy characteristics of evaluation factors, can scientifically calculate the weight value of each evaluation index, and combine qualitative and quantitative aspects, in order to objectively provide an evaluation of the classroom instructional quality of teachers, which is conducive to the high-quality construction of university courses.

Oil-bearing evaluation of different lithofacies in Da’anzhai Member, Central Sichuan Basin: implications for shale oil development

The Jurassic Da’anzhai Member of the Sichuan Basin has good prospects in shale oil exploration and development. However, the lack of research on the relationship between different lithofacies and oil-bearing property restricts the research on the geological theory and further exploration and development of shale oil in Da’anzhai Member. Based on core, fluorescence thin sections, rock pyrolysis, total organic carbon (TOC), extraction of chloroform bitumen ‘A’, and nuclear magnetic resonance (NMR) tests, the oil-bearing characteristics and reservoir physical properties in different lithofacies of Da’anzhai Member were analyzed. The results suggest that the oil-bearing and physical properties of shale are better than shell limestone and their peperite. The crude oil discharge from thick shale is limited because of the petrophysical property difference. The Da2b layer thick shale has the best shale oil exploration and development potential, which is the focus of the next step.