Laser Raman spectroscopy is a promising technique for real-time oil and gas detection in drilling fluids during drilling operations; however, the distribution of crude oil and its coupling with Raman spectral responses under varying temperature conditions remain insufficiently understood, which limits its quantitative applications in downhole environments. This study investigates the temperature- and concentration-dependent behavior of crude oil in oil-containing drilling fluids and develops a quantitative analytical method based on Raman spectroscopy for geological guidance. Crude oil is modeled as dispersed droplets within a continuous fluid phase, and Raman spectra are collected under different temperature and concentration conditions to establish a quantitative relationship between spectral intensity and crude oil concentration. Results show that crude oil exists as dispersed droplets whose size decreases with increasing temperature, accompanied by an increase in interfacial visibility, while higher concentrations lead to a more uniform volume distribution at constant temperature. Raman shifts within 1000–3000cm$^{-1}$ effectively characterize crude oil, with a dominant peak at 1519cm$^{-1}$, and a positive correlation between peak intensity and crude oil concentration is observed, particularly at elevated temperatures. Based on this relationship, a quantitative model for crude oil detection is established. The proposed method enables accurate real-time identification of oil-bearing formations with minimal influence from concentration variation or formation thickness, providing theoretical support and practical guidance for the application of Raman spectroscopy in LWD systems and improving drilling precision and reservoir evaluation efficiency.

This study investigates the Chang 4 + 5 ultra-low permeability reservoirs in the Jiyuan area of the Ordos Basin using integrated thin-section analysis, SEM, XRD, nitrogen adsorption, high-pressure mercury intrusion, NMR, and micro-CT techniques. By calibrating NMR with adsorption–intrusion data, a continuous multi-scale pore size distribution was established. The reservoirs are characterized by diverse pore types and pore-throat assemblages, with pore systems dominated by nanopores exhibiting a bimodal distribution. Sedimentary processes exert a primary control on grain size and sandbody architecture, resulting in pronounced reservoir heterogeneity, among which distributary-channel sandstones generally show more favorable reservoir properties. Diagenetic processes further modify the pore system: compaction and cementation reduce storage and flow capacity, whereas dissolution enhances effective pore development. Seepage behavior is strongly controlled by pore structure and can be summarized as “pores dominate storage, pore throats dominate flow.” Pore-throat size and sorting regulate bound-water occurrence and oil-phase flow capacity, while water-phase relative permeability curves exhibit two representative patterns. These results provide microscopic support for sweet-spot evaluation and efficient development of ultra-low permeability reservoirs.

In order to extract the remaining oil from the reservoir during the late stage of development, there is an increasing demand for precise research on the internal architecture of the reservoir. In this paper, the meandering fluvial point bar architecture of the Guantao Formation in Gudong Oilfield is quantitatively characterized through the integration of core, well logging, seismic data, and modern river geomorphology analysis. The models for the relationship between point bar length and width, as well as width and thickness, have been established. The investigation of modern meandering fluvial geomorphology shows that the point bar mostly undergoes downstream migration during lateral processes. In this context, geomorphologic parameters such as migration azimuth points, upstream deviation angle, and downstream deviation angle are proposed to quantitatively characterize the architecture of point bars. Statistical regression analysis of modern fluvial point bar geomorphologic parameters reveals a strong correlation between the upstream deviation angle and downstream deviation angle, as well as between the upstream deviation angle and the ratio of point bar width to looplength. Once the dimensions of the point bar and looplength are established, the upstream and downstream deviation angles can be determined, along with the migration azimuth points. The interlayer distribution pattern of the point bar can then be ascertained through a method of plane-profile interactive comparison. For small-scale architecture, the development proportion law of lithofacies in point bars is clearly discernible based on core data statistics. Subsequently, volume models for both point bars and different lithofacies are established.

The Dalazi Formation in the Yanji Basin is primarily composed of fan delta and lacustrine facies, with local development of alluvial fan deposits. The second member of the Dalazi Formation (Da₂) serves as the key oil-bearing interval for exploration and development. Based on logging data, lithological observations, and maximum entropy spectral analysis (MESA), Da₂ is interpreted to mainly represent a continental fan delta system. Due to the complex depositional environment, significant variations exist in sedimentary types, resulting in notable differences in both lithology and logging curves, which hinders regional correlation using conventional logging marker bed pairings. In order to solve this problem, based on the theory of high resolution sequence stratigraphy and astronomical cycle theory, this paper uses the maximum entropy spectrum analysis, spectrum analysis and wavelet time-frequency analysis technology to process and analyze the natural gamma curve (GR) data, and combines the logging lithology information to identify the sequence interface. According to the prediction error trend (INPEFA) curve in MESA, it is identified that Da2 contains 1 long-term base level rise half-cycle and 1 long-term base level fall half-cycle. On this basis, the mid-term base level cycle and short-term base level cycle are identified by combining spectrum analysis technology and wavelet time-frequency technology. Finally, The Da2 sequence is subdivided into 1 long-term, 6 mid-term, and 16 short-term base level cycles, based on which a sequence stratigraphic division scheme is proposed. Based on this, a high-resolution stratigraphic framework is established, which provides accurate geological basis for subsequent comprehensive reservoir evaluation and sand body prediction.

CO2 enhanced oil recovery (CO2-EOR) technology is an effective method for enhancing oil recovery and achieving carbon sequestration. During this process, part of the injected CO2 is permanently stored underground, while the rest is produced with associated gas and vented, causing environmental pollution, which contradicts the environmental principles of CO2-EOR. Therefore, separating and purifying the CO2 in associated gas is essential. Membrane separation technology, due to its compact footprint and strong adaptability, is particularly suitable for space-limited offshore drilling platforms. In CO2 separation membranes, mixed matrix membranes (MMMs), with their tunable structural characteristics and excellent separation performance, have become a research hotspot in recent years. This paper reviews the research progress of MMMs in the field of CO2 separation, focusing on the fillers and preparation methods of MMMs, and analyzes the challenges they face in associated gas treatment applications, such as high pressure, high humidity, and corrosion from acidic gases. Finally, this review identifies future research directions to promote the application of mixed matrix membranes in CO2 separation from associated gas.

Given that methane (CH4) and nitrogen (N2) have similar properties, achieving high-purity enrichment of CH4 from nitrogen-rich low-grade gas is extremely challenging and is of great significance for sustainable development in energy and the environment. This paper reviews the research progress on carbon-based materials, zeolites, and MOFs as adsorbent materials for CH4/N2 separation. It focuses on the relationship between the composition, pore size, surface chemistry of the adsorbents, CH4/N2 selectivity, and CH4 adsorption capacity. The paper also highlights that controlling pore size and atomic-scale composition and optimizing these features for the best match are key directions for the development of new adsorbents. Additionally, it points out that MOFs, which combine the advantages of carbon-based adsorbents and zeolites, are likely to become the most promising adsorbent materials for efficient CH4/N2 separation.

The conjugated structure of carbon is used in chemical sensing and small molecule catalysis because of its high charge transfer ability, and the interaction between carbon materials and small molecules is the main factor determining the performance of sensing and catalytic reactions. In this work, Reduced Density Gradient (RDG) and Symmetry-Adapted Perturbation Theory (SAPT) energy decomposition methods were used in combination to investigate the heterogeneity of catalytic substrates commonly used in energy chemistry with [6, 6] the carbon nanobelt ([6, 6] CNB, the interaction properties and mechanisms inside and outside the system). The results show that most of the attractive forces between dimers are provided by dispersive interactions, but electrostatic interactions cannot be ignored either. The total energy of the internal adsorption of [6, 6] CNB was significantly smaller than that of external adsorption, which led to the small molecules being more inclined to adsorb in the inner region of [6, 6] CNB. The dispersive interactions of small molecules adsorbed on [6, 6] CNB were also found to be very high. Furthermore, the dispersive interactions of the same small molecules adsorbed inside [6, 6] CNB were significantly stronger than those adsorbed outside. In [6, 6] CNB dimers, dispersion played a major role in the mutual attraction of molecules, accounting for 70% of the total attraction.

Dawangbei subsag is located in the north of Chezhen Sag. Deep-water nearshore subaqueous fan and fan delta are mainly developed in the northern steep slope in the member 3 of Shahejie Formation (ES3). With greatly complex sedimentary structure and no obvious mudstone interlayer, the stratigraphic division and correlation of glutenite reservoir in this area is difficult to be correlated and tracked. Aiming at this problem, this paper analyzes the logging data, clarifies the characteristics of sequence interface, introduces the theory of climate cycle driven by astronomical cycle in astronomy stratigraphy, studies the sedimentary formation conditions of glutenite, and identifies and compares the cycle interface of glutenite. The analysis results show that the stratigraphic cycles in the study area are mainly controlled by the long orbital eccentricity cycles of 400ka and the short orbital eccentricity cycles of 96ka. The thickness of the cycles is controlled by the long orbital eccentricity cycles and the short orbital eccentricity cycles ranging from 113.55 to 197.82m and 26.93 to 48m, respectively. The logging curves are filtered by the information of dominant cycle frequency. According to the filtering curve, the sequence is divided into different orders of sequence. After determining the partition scheme, ES3 is divided into 3 third-order sequences, 6 fourth-order sequences, and 28 fifth-order sequences, which builds the well correlation section and correlation framework of stratigraphic cycle from the provenance direction to the sag center.

In this work, based on density functional theory (DFT) and wave function analysis, the properties of absorption spectrum, electronic circular dichroism (ECD) spectrum and Raman spectrum of infinitene (monomer and dimer) with double helical structure are theoretically studied. The electronic excitation properties of infinitene were investigated based on the visualization method charge density difference (CDD) and transition density matrix (TDM). It is found that there is obvious intermolecular charge transfer behavior in the dimer. The electromagnetic interaction mechanism of the chirality of infinitene is explained by decomposing transition electric\magnetic dipole moments (TEDMs\TMDMs). The response of Raman spectra to excitation light of different wavelengths was calculated. Then, the electron delocalization degree and magnetic response intensity of infinitene were studied based on the magnetically induced current under external magnetic field. The interaction of infinitene with the external environment was studied by electrostatic and van der Waals potentials, and it was shown that non-polar or low-polar molecules are more inclined to be adsorbed at the groove position of infinitene. Finally, the mechanism of intermolecular interactions in dimer was investigated based on independent gradient model based on Hirshfeld partition (IMGH), Atoms-In-Molecules (AIM), and energy decomposition analysis based on forcefield (EDA-FF). And revealed that the stacking in the dimer is dominated by dispersive interactions.

Perovskite oxide SrFe0.9Mo0.1O3-delta (SFM) was evaluated as the electrode for symmetric solid oxide fuel cells (S-SOFCs) with Sm0.2Ce0.8O2-delta (SDC) and La0.9Sr0.1Ga0.8Mg0.2O3-delta (LSGM) electrolytes. Under reducing conditions at 800 degrees C, the SFM was reduced to be a multi-phase composite consisting of the single pemvskite phase, Ruddlesden-Popper (RP) layered perovskite phase, and Fe-0 phase. After reoxidation at 800 degrees C in air, this multi-phase system was again transformed into the parent perovskite phase again, indicating good redox reversibility of the SFM. At 700 degrees C, polarisation resistances of the SFM used as the cathodes on the LSGM and SDC electrolytes were 0.28 and 0.14 Omega cm(2), respectively, in air. Using H-2 as a fuel, the LSGM and SDC supported S-SOFCs with the SFM symmetric electrodes showed the peak power outputs of 253 and 269 mW cm(-2), respectively, at 700 degrees C. Finally, the good long-term stability and redox-cycling stability of the S-SOFCs further demonstrate the potential of the SFM as the symmetric electrode.

Trace elements in sedimentary rocks are highly sensitive to palaeoaquatic environmental changes in a sedimentary environment, making them an effective means for studying the paleoclimate and paleoenvironment during the deposition of sediments. The trace elements and major elements of mudstone cores sampled in the Binnan Oilfield in China were tested by inductively coupled plasma mass spectrometry (ICP-MS). Strontium (Sr), barium (Ba), vanadium (V), nickel (Ni) and boron (B), which are all sensitive to the sedimentary environment, were selected as discriminant indicators, and the sedimentary environment of the Shahejie Formation in the Binnan Oilfield was studied by combining with sedimentary indicators. The results show that the equivalent B content and the Sr/Ba ratio discriminate the research area for salt water and freshwater sedimentary environments. The V/(V + Ni) ratio is between 0.65 and 0.81, meaning that this area has a highly reductive sedimentary stratum. The trend of the Rb/Sr curve indicates that the paleoclimate of the Shahejie Formation changed from dry to humid and then back to dry.

After over 20 years of development in Daqingzijiang Oilfield, isolated sand bodies under the delta front and pro-delta in the Qingshankou Formation(qn)have become important oil and gas reservoir bodies. However, the cause for large amounts of isolated bar sand bodies in the lake-basin delta sediment system has not been reported in China. This article, through core observation, reveals plenty of evidence that there storm waves once existed. Combined with paleogeography and hydrodynamic force analysis, it describes the transformation effect of waves on delta sand bodies and on the formation mechanism of bar sand bodies. Based on a study on paleogeomorphology and the statistics of sand body distribution, we consider ‘Storm waves conveying sand’ and ‘landform controlling sand’ as the cause and distribution model of the delta’s isolated bar sand body formation. We also think that the superposition of multiple bar sand bodies is the direct cause of the strong anisotropy in reservoirs and the complex relationship between oil and water in reservoirs. Most of these sand bodies have formed into lenticular lithologic hydrocarbon accumulations. On the basis of this integrated study on hydrocarbon accumulation, we set up an accumulation model of lenticular hydrocarbon accumulation involving the variables ‘Surrounded by source rocks to generate hydrocarbon’, ‘Driven by pressure difference’, ‘Migration through multi pathways’ and ‘Accumulation by filtering water’.

The Dainan formation reservoirs in Shaobo area, Gaoyou sag, Southern China, sedimented mass conglomerates dominated by lacustrine slope apron system which fended by multiple flood channels with massive terrigenous clasts. In the early days, offshore fan-shaped sediments in the Shaobo area of the Gaoyou Sag were considered to be the main sedimentary system. However, a new lacustrine sedimentary model is presented in this paper. By careful core description and interpretation, four facies unions are recognized: (1) Facies union 1: Downslope clastic pathways that composed of massive conglomerates up to 6-25m thick, alternating with brown-dark gray mudstone and the etching structures can be often observed; (2) Facies union 2: Debris-flow Lobe is composed of massive conglomarates, matrix-supported to clast-supported polymictic conglomerates up to 10-50m thick; (3) Facies union 3: Underwater distributary channel is composed of trough cross-stratified sandstone, horizontally stratified sandstone and ripple cross-stratified fine to medium-grained sandstone, up to 5-20m thick; (4) Facies union 4: mudstone is dominates by thick grey black mudstone interbeding thin sandstone, the etching features are rare and bedding is typically parallel. In our study area, the traction current deposits constitute the producing petroleum reservoirs, and the conglomerates deposits are poor reservoirs. The sedimentary model may be applicable to other fault depression for predicting reservoir distribution.

The Shahejie Formation in Huimin Sag is an important crude oil/natural gas reservoir stratum. The results show that (1) in the study area, the Sr/Ba value of Shahejie Formation ES4, ES3, and ES2 in Huimin Sag is 0.55–0.58, showing that these were freshwater-brackish water environment with a continental deposition; the average Sr/Ba value of the first member of Shahejie Formation (ES1) is 1.88, showing that it was a salt water environment. (2) B element method of paleo-salinity analysis shows that in ancient times, the salinity of ES1 was the highest; ES2 and ES4 had basically the same salinity that were lower than that of ES1; the third formation of Shahejie Formation(ES3) had the lowest salinity. (3) Analysis of values of Fe/Mn, Mg/Ca, and paleoclimate index C shows that the Shahejie Formation had generally a semi-dry climate. (4) Based on the analysis of the paleoenvironment, combined with the description of the cores, a sedimentary evolution model is built: ES4 was a debris flow fan-shaped river delta sediment in a shallow lake environment; ES3 was a delta-deep water fan-shaped system in a semi-deep-deep lake environment; ES2 was a delta system in semi-shallow lake environment; ES1 is the semi-shallow lake environment, the main sedimentary facies is the shore shallow lake facies.

重力流沉积体系砂体展布规律极为复杂,通过重力流流体实验,确定了重力流沉积不同岩相的成因及展布规律,并在此基础上,通过岩芯观察及测井、录井资料分析,在滨南油田古近纪沙三下亚段进行重力流砂体展布规律研究,研究结果表明:1)塑性流体在运动过程中被稀释,导致颗粒支撑机制发生复杂的变化,从而出现多种流态的流体,因此塑性流体被稀释到一定程度后会转换为液态流体;2)重力流沉积层序的垂向演化及横向变化是流体性质演化的结果,即地质记录中的复杂重力流层序为流体性质转换后再沉积的结果;3)重力流垂向层序与沉积模式的有机结合是进行砂体展布预测的关键.在该模式的指导下,明确了滨南油田沙三下亚段岩相的空间展布和变化规律.

During the Second Member of Shuangyang Formation of Moliqing fault in the Yitong Basin, northeast of China, the intermittent transportation and rapid accumulation of nearshore gravity flows make the facies belts of fan apron narrow and changefully. Lacking stable contrastive maker layers, while the several tectonic events such as strike slip, transtension and compression occurring in the later period make the stratigraphic distribution of this area more complex. For these reasons, the research on stratigraphic correlation and the distribution of sedimentary facies are extremely difficult. To solve the above problems, this paper proposes the following solutions: (1) This paper assists to achieve the stratigraphic cycle analysis through logging data entropy spectrum analysis, on which basis and combining with the core data, seismic interfaces and geological markers to achieve the division and correlation of small layers of single sand body; (2) By analyzing the coarse clastic sedimentary system, we research the coarse clastic glutenite sediments of Shuangyang Formation in Moliqing fault from the fluid properties and fluid type conversion so as to clearly understand the vertical sequences and horizontal distribution characteristics analysis of core facies as well as deduce the fluid type of supply source and the characteristics of sediments. The results show that: (1) The sequence development is dominated by tectonic movements, and the strata can be divided into 5 middle-term cycles and 25 short-term cycles adopting T-R mode; (2) studies suggest that because the fluid property of supply source occurs cyclical changes under the condition of multiple sources, and the fluid shows alternation and conversion between gravity flow and traction flow under the control of particular ancient landform, therefore, the sediments of researched area form a mixed sedimentary system of gravity flow and traction flow. On the basis of source characteristics and sedimentary characteristics analysis, this paper proposed the sedimentary type of continental facies slope apron, which is divided into three sub-facies: proximal, middle and distal sub-facies. Among them, proximal sub-facies mainly develop the slop channel sedimentation dominated by mud debris flow deposits, central sub-facies develop the superposition channel microfacies dominated by mix depositions of gravity flow and traction flow and the leading edge microfacies of fan dominated by traction flow, while the distal sub-facies is mainly based on the thin sheet sand body and gravity flow slump depositions.

The conglomerate layer at the upper section of the 4th member of the Shahejie formation(S-4(u)) of the Yongan district at the Donying depression is a well-developed sedimentation of several periods. It lacks stable muddy layers and sophisticated classification of the sedimentation periods and the proportion of sedimentary layering in each period has long been a difficult task for geologists. In addressing this problem, this paper attempts to introduce the theory of climatic cycles driven by astronomical periods from astronomical stratigraphy on the basis of the characteristics of the sedimentation under the turbidity current in the region of study. Through studying the conditions for the formation of the conglomerate layer and the factors of control, we pinpoint the formation of the layer in chronology and differentiate the cycle interface and correlation in the same formation period. Milankovitch analysis is conducted on the sedimentation of the conglomerate layer in the region of study to determine if the stratigraphy cycle of the region is primarily controlled by the eccentricity cycle and calculate MSC1 and MSC2 thicknesses of 189.3 m and 78.05 m, respectively. Milankovitch theory is the primary tool used in the analysis, in conjunction with petrographic analysis. The stratum at the S-4(u) is classified into four IV-grade sequences and 11 V-grade sequences. The information on the dominant cycle frequency is used for wave filtering of the well logs and to determine the significant Milankovitch wave log. With the data from this curve, we may compare the stratigraphy cycle with the characteristics of the standard cycle and classify and compare the sedimentation periods of the conglomerate layers in further detail.

Sandy conglomerate is the major sedimentary systems in the upper fourth member of Shahejie formation in Shengtuo area. In this paper, on the base of core observation and description, sedimentary characteristics are studied in the upper fourth member of Shahejie formationin Shengtuo area. The results show that the prograded-type fan delta is the major sedimentary system in Shengtuo area. There are two major sedimentary types: traction current deposits which is the most strikingly signified by Parallel bedding sandstone containing gravel, and debris flow deposits which is the most strikingly signified bymassive bedding sandy conglomerate.

Overlapping gravity accumulation bodies were formed on the northwestern steep slope of the Shuangyang Formation in the Moliqing fault depression of northeast China. This study analyzed in detail the spatial distribution of the lithofacies and lithofacies associations of these accumulation bodies based on more than 600 m of core sections, and summarized 12 major types of lithofacies and three types of lithofacies associations: (1) the proximal zone consists of gravelly debris flows dominated by alluvial channel conglomerates; (2) the middle zone is dominated by various gravity flow deposits and traction flow deposits; and (3) the distal zone is dominated by mudstones with intercalations of sandy debris and turbidites. Combining with the grain size cumulative probability curves analysis, we determined the transformation of debris flows to sandy debris flows and to turbidity currents in the slope zone of the basin margin, and further proposed a lacustrine slope apron model that is characterized by (1) an inconstant multiple source (line source), (2) an alternation of gravity flow deposits and traction flow deposits dominated by periodical changes in a source flood flow system, and (3) the transformation of sandy debris flow deposits into distal turbidity current deposits. This sedimentary model may be applicable to other fault depressions for predicting reservoir distribution.