Strong Cementation Research Articles

Distributary channel type and high‐quality reservoirs in tight sandstone—A case study on the outcrops and reservoirs of Xujiahe formation in Western Sichuan Basin

AbstractThe distributary channels in shallow‐water delta are well‐developed in tight sandstone. There are few studies on the channel type and diagenetic differences among them. To illustrate the relationship between channel types and high‐quality reservoirs, this study summarizes the lithofacies types and sequences in the second member of the Xujiahe Formation. We use core data, outcrops, and modern sediments observation, scanning energy spectrum, and rock thin sections. The lithofacies can be divided into 15 types, and there are four types of vertical lithofacies sequence. Lithofacies sequences are different in lithofacies, channel scale, reservoir porosity and permeability, and so forth. They are formed in various hydrodynamic environments. With the continuous bifurcation of the channels, the width and depth of the channels are decreasing, forming different lithofacies sequences. Four types of distributary channels are classified. The characteristics of these channels are described, and the sedimentary models are established. Distributary channel types are related to the diagenetic process. Channel type I and the bottom of type II develop moderate compaction–dissolution diagenetic facies, the middle and upper parts of type II and type III can develop strong compaction, moderate compaction–dissolution, or strong cementation diagenetic facies, and type IV can develop strong compaction diagenetic facies. High‐quality reservoirs are developed in limitedly distributed in distributary channels of type I and type II, and part of type III. This study provides a useful view for evaluating high‐quality reservoirs based on distributary channel types.

Biomass ash (BA) waste as an activator to produce carbon-negative cement

The use of biomass, as a renewable energy source, to run heating and power plants is propelled by sustainable European policy. Olive is an important resource in Mediterranean countries. The residues from the extraction of olive oil are used as biomass, either to produce the oil or to generate heat or electricity. The disposal of ash residue poses an important burden. This study uses olive pit bottom ash waste (OBA) to produce carbon-negative cement. The OBA is mixed with waste GGBS (GGBS), and neither calcination nor thermal curing are used to lower environmental impact.The cements produced contain up to 60 %OBA and have a carbon sequestration capacity up to -97.45 kg CO2e/m3. An optimum mix with 40 %OBA is developed (using auxiliary activator), with compressive strength of 36–44 MPa and a carbon sequestration capacity of 40–45 kg CO2/m3. A modified loss on ignition test is proposed to evaluate the embodied carbon of biomass ash.The OBA's main chemical constituents: K2O and CaO, afford outstanding activation and alkalinity to release Ca2+ Si4+ and Al3+ from GGBS to form calcite, hydrotalcite, C-(A)-S-H and amorphous cements. Using sodium carbonate (NC) and lime as supplementary activators enhanced the mechanical properties of the cements and slightly changed their composition and microstructure. NC is the most efficient activator, it increased dissolution, and produced a denser and stronger cement with higher Si and K concentration that includes gaylussite, N-A-S-H and C(K)-A-S-H. Pre-dissolving the NC prior to mixing increases the activator's efficiency, producing less calcite cement for the same amount of NC. By adding 4 % pre-dissolved NC, the compressive strength increased by 138.76 % (compared to OBA-GGBS mortar without auxiliary activators) and 113.94 % compared to the material with NC in powder form.

Sedimentological and diagenetic facies of tight sandstones in lacustrine delta-front: A case study of the Jurassic Lianggaoshan Formation, eastern Sichuan Basin

In this study, taking the Jurassic Lianggaoshan Formation (J1l) tight sandstones in the eastern Sichuan Basin as an example, the types and well-logging responses of main sedimentological and diagenetic facies in the lacustrine delta-front are investigated based on summarizing the sedimentary characteristics and reservoir properties. Subsequently, further validation and application are conducted in the study area through machine learning. Research results show that the J1l lacustrine delta-front in the eastern Sichuan Basin mainly develops subaqueous distributary channels and mouth bar sand bodies, exhibiting typical densification reservoirs, with porosity and permeability distributed between 0.48% and 11.24% (av. 3.87%) and 0.0003–0.653 × 10−3 μm2 (av. 0.026 × 10−3 μm2), respectively. Strong compaction and strong cementation are the primary factors leading to densification, whereas chlorite coatings and weak dissolution play constructive roles in preserving some primary pores, creating a small amount of dissolution pores, and enhancing permeability. In terms of manifestation, the pore-throat content with a radius greater than 0.006 μm governs the reservoir quality. Furthermore, five types of diagenetic facies are identified in the J1l subaqueous distributary channels and mouth bars: strong compaction facies (Type I), strong cementation facies (Type II), chlorite-coating and intergranular pore facies (Type III), weak dissolution and intragranular pore facies (Type IV), and medium compaction and cementation facies (Type V). Overall, the thick and coarse-grained subaqueous distributary channels can be considered as the preferred exploration targets for tight oil and gas, with type III and type IV diagenetic facies being the most favorable reservoirs, characterized by well-logging responses of high AC and low GR, DEN, and RT. Based on the fine division of sedimentological and diagenetic facies, establishing well-logging interpretation models and then employing machine learning to achieve sweet spot reservoir prediction can provide valuable insights for tight oil and gas exploration in regions lacking core data.

Research on the Diagenetic Facies Division and Pore Structure Characteristics of the Chang 63 Member in the Huaqing Oilfield, Ordos Basin.

In tight sandstone reservoirs, diagenesis has a significant impact on the development of reservoirs and pore structures. To clarify the effect of diagenesis on the pore structure of tight sandstone, 12 samples of the Yanchang Formation in the basin were studied based on experiments such as high-pressure mercury intrusion and low-temperature nitrogen adsorption. The diagenetic facies in the study area are divided into two categories: strong cementation facies of carbonate minerals and strong compaction facies of soft component minerals, which are relatively unfavorable diagenetic facies, and stable facies of felsic minerals and strong dissolution facies of feldspar minerals, which are dominant diagenetic facies. The pore structure of the Chang 63 reservoir in the study area has obvious fractal characteristics, with a fractal dimension D 1 greater than D 2 and a greater heterogeneity of large pore throats. Compared to compaction and cementation, dissolution has a stronger controlling effect on the pore structure of reservoirs. In tight sandstone reservoirs with low porosity and permeability, dissolution has a more important impact on reservoir transformation and development. The intensity of different types of diagenesis in the Chang 63 reservoir affects reservoir heterogeneity, and the level of the reservoir heterogeneity affects the complexity of reservoir pore structure. In tight sandstone reservoirs, cementation has a stronger controlling effect on the structural complexity of large pores, while dissolution has a stronger controlling effect on the structural complexity of small pores. The dissolution has a strong control effect on the physical properties of the reservoir. This study provides insights into the relationships among the diagenetic facies, reservoir quality, and pore structure of tight sandstone reservoirs. This study has reference significance for the exploration and development of tight oil in the research area.

Investigation of chemical processes in cement exposed to wet ScCO2 and CO2-saturated brine in geological CO2 storage conditions

In geological CO2 storage conditions, wellbore cement can be exposed to both supercritical CO2 (ScCO2) with water vapor, and CO2 dissolved in water. There is a lack of studies that investigate the effects of reaction environments on the extent of CO2-induced cement carbonation and leaching. In this study, four CO2 exposure experiments were designed with wellbore cement samples exposed to both ScCO2 and CO2 dissolved in water to investigate the impacts of evaporation, capillarity, diffusion, and salt deposition on cement carbonation. Severe cement carbonation after 14 and 28 days of CO2 exposure was observed in a wet ScCO2 phase. When water evaporation into ScCO2 phase was minimized by a steel plate between the brine phase and the ScCO2 phase, a strong cement carbonation in ScCO2 phase was still visible. The reason was that imbibition and diffusion drove water to migrate from the lower section to the upper section of the cement sample to participate in the carbonation reaction. The level of cement carbonation in different CO2 exposure environments was ranked as: wet ScCO2 > CO2 dissolved in water > Pure-ScCO2. The corresponding maximum carbonation area ratios were 90 % and 38 % for the wet ScCO2 scenario and the brine scenario, respectively, compared with a maximum carbonation area ratio of 20 % for the Pure-ScCO2 scenario. This study implies that the most altered region in wellbore cement is at the ScCO2—water interface, and the expansion rate of the altered region is the key to evaluate the potential for CO2 leakage through wellbore cement.

Archie's cementation factors for natural rocks: Measurements and insights from diagenetic perspectives

Archie's cementation factor, m, is a critical parameter for petrophysical studies, and the value is influenced by several factors such as the shape, type, and size of grains, degrees of diagenesis, and associated pore structure. Using integrated experimental and theoretical approaches, the goal of this study is to obtain the cementation factor of rocks (both reservoir rock and caprock) and assess the impact of diagenetic processes on the values of the cementation factor. Thirteen samples of geologically diverse rocks (six mudstones, four fossiliferous limestones, two marbles, and one sandstone) were selected to achieve these research objectives. Two approaches, the diffusion of gas tracers and the Bosanquet formula calculation using pore-throat sizes from mercury intrusion porosimetry analyses, were used to derive the cementation factors of these rock samples. These rocks were categorized into two groups based on the correlation between average pore-throat diameter and diffusivity, and an exponential-law relationship between the cementation factor and porosity was determined for these sample groups. In addition, thin-section petrography and field emission-scanning electron microscopy observations were utilized to investigate diagenetic processes, with four diagenetic patterns being established: (1) strong compaction, strong cementation, and weak dissolution-diagenesis pattern; (2) weak compaction, medium cementation, and weak dissolution-diagenesis pattern; (3) weak compaction, medium cementation, and strong dissolution-diagenesis pattern; and (4) fracture-matrix pattern. The results indicated that diagenetic processes and microfractures contribute to the variability in the cementation factors of these rock samples.

Organic Matter Source, Fluid Migration, and Geological Significance of Stylolites in Organic-Lean Carbonate Rocks: A Case from the Sichuan Basin

Carbonate rocks exhibit significant heterogeneity as both a source rock and reservoir. Stylolite formation plays a crucial role in the enrichment of organic matter and the migration of geofluids within carbonate rocks. In order to study the enrichment mechanism of organic matter and the geofluid migration mode in the stylolites developed in carbonate rocks, stylolite-bearing core samples from the Dachigan structural belt in the eastern Sichuan Basin were collected. The stylolites and matrix were subjected to the total organic carbon (TOC) test and Rock-Eval pyrolysis, thin-section observation under fluorescent light, whole-rock X-ray diffraction, carbon and oxygen isotope analysis, and scanning electron microscopy. The organic matter occurring in the stylolites is mainly in the form of three types: soluble organic matter, pyrobitumen, and bitumen. This suggests that the organic matter within the stylolites mainly consists of secondary migrated organic matter. The stylolites also exhibit well-developed secondary dolomite and pyrite resulting from late-diagenetic recrystallization. These minerals contribute to the preservation of intercrystalline pore spaces and fractures, providing favorable conditions for oil and gas accumulation and migration. The strong cementation observed at the contact between the stylolites and matrix, along with the presence of secondary minerals nearby, may be attributed to the fractionation of light and heavy oil components during the migration of hydrocarbon fluids from the matrix to the stylolites. The thicknesses of the stylolites vary within the bulk, indicating severe diagenesis in thinner areas. Consequently, this leads to significant fractionation effects. The fractionation of crude oil components by stylolites poses challenges for the study of definitive oil–source correlations. To overcome these challenges, future research could investigate biomarker compounds to attempt oil–source correlations. Additionally, future efforts should take into consideration the spatial variation in the crude oil properties. Understanding the role of stylolites in organic matter enrichment and geofluid migration is crucial for optimizing exploration strategies in the Sichuan Basin, a region of growing importance in the energy industry. Moreover, our findings shed light on the complex interactions within stylolite-bearing rocks, which are not limited to this specific basin. These insights offer valuable contributions to the broader field of geology and reservoir characterization, enhancing our ability to predict and interpret similar geological formations globally.

Differential Diagenesis and Pore Evolution Characteristics of Different Sedimentary Microfacies Reservoirs of Bioclastic Limestone: A Case Study of MB2-MC1 Section in X Oilfield in The Middle East

In order to clarify the differential diagenesis of different sedimentary microfacies of bioclastic limestone in Cretaceous M Formation in the Middle East and systematically analyze the characteristics of reservoir pore evolution, the data of regional geology, well logging, core, cast thin section, scanning electron microscope, three-dimensional CT and conventional porosity and permeability test are comprehensively used, taking MB2-MC1 section in X oilfield as an example, starting from the diagenesis and pore evolution of bioclastic-arene shoal, the characteristics of diagenesis of each sedimentary microfacies in different environments are analyzed, and the differential diagenesis, pore evolution process and its influence on physical properties are studied. It is showed that the reservoirs of MB2-MC1 section are mainly developed in the ramp shoal and platform margin shoal. The shoal facies can be further subdivided according to the type of bioclastic debris. The sedimentary microfacies determine the original fabric and bioclastic type of M Formation, and then control the diagenetic sequence and strength. Each sedimentary microfacies mainly experiences different degrees of mud crystallization and burrows in seawater environment, dissolution and cementation in atmospheric freshwater environment, compaction, pressure solution and dolomitization in burial environment. High energy microfacies have the characteristics of non-selective dissolution, mainly developing intergranular pores and intergranular dissolved pores. Medium energy microfacies have the characteristics of selective dissolution, mainly developing mould pores and intragranular pores. The medium-low energy microfacies have the characteristics of moderate cementation, moderate compaction and moderate-weak dolomitization, mainly developing intragranular pores and visceral foramen pores. The low energy microfacies have the characteristics of strong cementation, strong compaction and moderate dolomitization, mainly developing micropores, intercrystalline pores and visceral foramen pores, which are non-reservoirs.

Development of compositions of slag-alkaline binding materials for pavement products

In this work, blast furnace granulated slag of the Kamet-Stal plant was investigated. It was established that the slag belongs to the basic ones. According to the quality factor, the slag belongs to grade 1 and can be used to fabricate slag-alkaline binding material by the alkaline method of activation. A significant part of the slag is in an X-ray amorphous state, which contributes to the production of strong cement stone in the late stages of hardening. The crystalline phases of the slag exhibit weak binding properties and provide strength to the hardened slag-alkaline binding material. To activate the slag and plasticize the composition, portland cement and clay were introduced into it, sodium liquid glass, caustic soda solution and soda ash solution being used as an alkaline sealer. The exclusion of clay from the basic composition leads to an increase in strength almost twice due to additional activation of slag with portland cement. A significant drawback in this case is the numerous precipitates that appear on the samples already on the first day of hardening. Thus, for accelerated curing times, increased mechanical strength, reduction in the amount of leaching and a significant reduction in the cost of finished products, we suggested the composition containing 91 wt.% slag; 6 wt.% clay; and 3 wt.% portland cement closed with a solution of liquid glass with a modulus of 2.3 and a density of 1300 kg/m3.

Nanopore structures and controlling factors of the Early Cambrian shale reservoir in the Middle Yangtze Platform, South China

At present, the characteristics and controlling factors of nanopore structure in shale reservoirs are still not well understood owing to the concurrence of both organic matter (OM) and inorganic mineral (IM) pores. This issue is more prominent for the Early Cambrian shale in South China owing to the greatly variable nanopore structures of the samples from different areas. In this study, a set of Early Cambrian shale samples was taken from an exploration well in the Middle Yangtze Platform, a newly-determined shale gas play with a great potential outside the Sichuan Basin, their OM-removed (OMR) samples were obtained by a high-temperature oxidation method, and the pore structures of the bulk shales and their OMR-samples were analyzed by low-pressure gas adsorption experiments. The OM nanopore structure parameters of shale were calculated, and the controlling factors of OM and IM nanopores in the shale were investigated. The results show that the shale nanopores are mainly mesopores, their OM nanopores, especially OM micropores, are obviously more developmental compared with the IM nanopores. The TOC content is the dominant influencing factor of the shale nanopores. The brittle minerals support the formation of interparticle pores, and provide protection to OM pores. The clay minerals provide a certain amount of nanopores, but the strong compaction result in rich micropores. The carbonate minerals decrease the shale nanopores owing to the strong cementation. The favorable area of shale gas in the Early Cambrian strata in the studied area was predicted by the TOC content and preservation conditions.

Fluid evolution and related fluid–rock interactions of the Oligocene Zhuhai sandstones in the Baiyun Sag, northern margin of the South China Sea

Pore fluids control the diagenetic processes and storage spaces of deep clastic rock reservoirs and have become a major area of interest within the fields of sedimentology and petroleum geology. This paper aims to relate the diagenetic processes of the Oligocene Zhuhai sandstones in the Baiyun Sag to pore fluids varying with burial depth. The types and distribution patterns of authigenic minerals are investigated through analysis of petrographic, mineralogical, and geochemical features to illustrate the origin and flow patterns of pore fluids and their influences on reservoir diagenesis. Strong cementation of eogenetic carbonate cement near the sandstone–mudstone interface was a consequence of material migration from adjacent mudstones on a large scale. The pore fluids were mainly affected by microbial methanogenesis and carbonate mineral dissolution in adjacent mudstones during eogenesis. The pore fluids were diffusively transported in a relatively open geochemical system within a local range. Support for this model is provided by the heavier stable isotopic values present in eogenetic calcite and dolomite. Feldspar dissolution during early mesogenesis was spatially accompanied by the precipitation of authigenic quartz and ferroan carbonate cement. Pore fluids in this period were rich in organic acids and CO2, and their migration mechanism was diffusive transport. The obviously lighter carbon and oxygen isotopic compositions of the ferroan calcite support this inference. During late mesogenesis, the input of deep hydrothermal fluid might have been partly responsible for the precipitation of ankerite, barite and authigenic albite. Oil charging may have inhibited carbonate cementation and compaction, accordingly preserving porosity, and together with authigenic kaolinite, might have promoted the transition of the reservoir from water wet to oil wet to the benefit of oil entrapment. The findings reported here shed new light on the evaluation and prediction of sandstone reservoirs that have experienced multiple periods of fluid flow.

Metoda sidetrackingu oparta na wykonaniu dwóch okien w kolumnach rur o różnych średnicach

While drilling from a vertical shaft the orientation of the diverter is carried out with the help of a magnetometer, leaving an interval of 18 m from the casing. The length of the milled interval could be reduced if a gyroscopic compass is used to orient the BHA. The open borehole section is covered with a strong cement sheath. To avoid magnetic interference, the bridge is drilled down to a depth of 6 m above the bottom of the open interval. A disadvantage of the full casing section milling method is an increased requirement on the strength of the cement bridge for drilling, and the difficulty in finding the head of the lower casing section if it needs to be drilled through after the sidetrack. In many cases, the mechanical drilling rate is limited by the conditions for removing cuttings, and for a horizontal section, the problem of removing cuttings becomes even more complicated. The design of modern milling tools is meant to produce small swarf that does not form clusters and is easily removed from the hole. During milling, it is preferable to flush the well with polymer drilling muds rather than clay muds. Hydrocarbon-based muds are not recommended for milling at all. An alternative to milling the entire casing cross-section is to make windows in the casing. This requires the installation of an oriented whipstock and the milling of the window in several stages. After a whipstock is positioned in the required direction, the stud connecting it with a milling machine of the first stage is cut off. On this basis, the paper proposes a method of sidetracking.

Evaluating the Impact of Crushing Process on Strength Characteristics and Leachability of Cement-Stabilized Dredged Sediment

Stabilization of dredged sediment and reusing the mixture as a construction material is an effective way to reduce environmental problems and save natural resources. However, the crushing process that occurs during construction may affect the mechanical properties and leachability of the reused stabilized soil, an issue that is less reported. Therefore, consolidated undrained triaxial tests and semi-dynamic leaching tests were conducted on stabilized sediments and recompacted crushed stabilized sediment grains (SG) to evaluate the influence of the crushing process. The results of the triaxial tests showed that the stabilized sediment exhibited strain-softening and brittle behaviors under various confining pressures (100, 200, and 400 kPa), while strain-hardening and ductile behaviors were more obvious in the SG. The reduction in cohesion between stabilized sediment and the SG reflected a loss of cementation bonding during the crushing process. The overall leaching behaviors versus curing time of heavy metals (As, Cr, Cu, Zn, Pb, Ni, and Hg) in stabilized sediment was similar to that of SG. The leaching mechanism indicated a good immobilization of heavy metals in stabilized sediment, while their stability in SG was poorer. The reason for the differences in triaxial strength properties and leachability were mainly attributed to the fact that the strong cementation bonding was destroyed by the crushing process, weakening the soil structure and raising the potential for release of elements.

Evidence of deep fluid activity in Jurassic tight sandstone reservoirs in the Northern Kuqa Depression

Understanding diagenetic fluid types and their effects on diagenesis is important to identify the main control factors of reservoir characteristics and predict reservoir sweet spots. Reservoir space destruction caused by strong cementation is notable in the Lower Jurassic Ahe Formation sandstones near the deep-rooted fault (Yiqikelike Fault) in the Kuqa depression. Different authigenic minerals and widely varying cementation contents indicate the complexity of diagenetic fluids. Therefore, we investigated strong cementation using petrographic and geochemical methods, including cathodoluminescence, scanning electron microscopy, laser ablation inductively coupled plasma mass spectrometry, and stable isotope analysis. The contents of authigenic quartz and calcite increased as they approached the deep-rooted fault, with maximum concentration of quartz and calcite of up to 8.73% and 8.92%, respectively. Abnormally high homogenization temperatures of the fluid inclusions were observed in the quartz overgrowth, one of which reached 156 °C. In calcite, the rare earth element Eu exhibited abnormal characteristics, and the carbon isotopes ranged from −8.00‰ to −2.00‰. Therefore, it is likely that deep fluids are involved in reservoir diagenesis near a deep-rooted fault. This study provides a good example of diagenetic evolution in deep sandstone reservoirs and the negative effects of the involvement of deep fluids in diagenetic processes.

An updated binary medium constitutive model of frozen rubber reinforced expansive soil under confining pressure

Rubber reinforcement can effectively improve the swelling characteristics and shear strength of expansive soil. However, rubber-reinforced expansive soil has a more complex structure and mechanical properties, especially in a frozen state, and existing models have not been applied to fully characterize its shear deformation characteristics. In this paper, the updated binary medium model of rubber-reinforced expansive soil is proposed based on the theory of the binary medium model and the homogenization theory of heterogeneous material. The deformation and damage mechanism of frozen rubber-reinforced expansive soil is discussed by using the concept of the binary medium model at the microscopic level, and the updated binary medium model is verified by the triaxial tests of frozen rubber-reinforced expansive soil under confining pressure conditions. The main results obtained: (1) Based on the theoretical framework of rock and soil failure mechanics and the concept of updated binary medium model, saturated frozen rubber-reinforced expansive soil can be abstracted into cementing elements (ice-rubber-soil skeleton) with strong cementation properties, elastic friction elements (rubber) and elastic–plastic friction elements (ice-soil broken skeleton) without cementation properties. (2) The stress–strain curve of frozen rubber-reinforced expansive soil can be divided into three stages: linear elastic stage (ε < 1.33%), elastic–plastic stage (1.33 % < ε < 4.17%) and strain softening stage (ε > 4.17%), which can be interpreted by the conversion between the cementing elements and the friction elements in the updated binary medium model.(3) The measured values of stress and strain of rubber-reinforced expansive soil match the calculated values of the model (R2 = 0.92), and the peak point strain deviation and stress deviation of the model and test values are 9% and 3%, respectively, indicating that the updated binary medium model can better simulate the stress–strain relationship of rubber-reinforced expansive soil. (4) The fitting degrees of the unary medium model and the binary medium model are 0.74 and 0.36, respectively. Compared with the updated binary medium model, there are fewer parameters in the equations, the binary medium model species lacks rubber as an elastic material, and the unary medium model lacks elastoplastic and elastic materials, so it is not suitable for simulating the stress-strain relationship of frozen rubber-reinforced expansive soil.

Vibrational &amp; Curling Analysis of Reinforced Concrete Multistory Building under Different Zone’s

The plan is explored for the gravity loads and also for the equivalent loads for examplecurling load in zone-ii (Bhopal), zone-iii (Nagpur), zone iv (Delhi), zone-v (Calcutta), zone-vi (Darbhanga).The structure is made on the thing known asstaad.pro v8i. This appraisal is the assessment of the Reinforced strong cement multi-story building (G+10). The codes utilized for the evaluations ofDead weight are IS:875(Part 1)- 1987 ,for live weight the code IS :875(Part 2)-1987 and for the incorporates of curling power in various breeze zones are IS:875 ( section 3) - 1987.The deferred outcome of these appraisal shows the adjustment in powers, clearings responses and weight of steel the proportionof partner material expected to repudiate equivalent loads will expandcertainly. Amount of essential material expected to contradict sidelong loads will augment drastically.

The characteristics and genetic mechanisms of the Upper Permian Shangwuerhe clastic reservoir in the eastern Junggar Basin, Northwest China

In this paper, the lithology, pore type, throat structure, and physical characteristics of the sandstone and conglomerate reservoirs of the Upper Permian Shangwuerhe Formation in the Fukang Sag of the Junggar Basin were analyzed through rock cast thin section, scanning electron microscopy, fluid inclusions, piezometric mercury, and porosity–permeability analysis. In addition, the reservoir densification mechanism and the genesis of deep effective reservoirs were discussed. The results show that the reservoir is dominated by lithic sandstone (or lithic sandstone conglomerate). The lithic fragments primarily comprise tuffaceous volcanic rocks, supported by grains and cemented by clay, carbonate, authigenic quartz, and laumontite. The reservoir properties are characterized by extra-low porosity and permeability, and the pore type is dominated by inter- and intragrain dissolved pores of lithic fragments, feldspar, and quartz. The pore connectivity is poor due to poorly sorted extra-fine throat channels. The tightness of the reservoir.is due to the strong cementation of calcite, chlorite, montmorillonite, illite-montmorillonite mixed layer, authigenic quartz, and laumontite. Furthermore, the large amount of Ca2+ released by the hydration of tuff rock debris and intermediate–basic volcanic rock debris and the CO2-rich thermal fluid from the deep layers cause the development of several calcites. The formation of several montmorillonites is mainly related to the alteration of filled volcanic ash, and the hydration of volcanic tuff material primarily causes the development of laumontite cementation. The dissolution of feldspar and various volcanic lithic fragments by acidic fluids triggers the physical improvement of the reservoir in the local section.

Particle size distribution analysis of mudstone based on digital image processing

Mudstone is becoming increasingly important for unconventional oil and gas development. The morphological characteristics of clastic are not only contributions to the 3D framework of mudstone, but they can clearly affect the physical properties of a mudstone reservoir, including surface area, pore-size distribution, and porosity. However, it is very difficult and time-consuming to measure the particle size distribution (PSD) of mudstone because of its small particle size and strong cementation. However, because of the importance of oil and gas extraction, it is urgent to develop a fast, accurate, and objective analysis method to measure the PSD of mudstone. Based on a comparison of various PSD measurement methods commonly used in the energy industry and geology, the best PSD measurement method for mudstone should be digital image processing. Two imaging methods, trainable Weka segmentation (TWS) and black mudstone particle size measurement, were used to analyze sections of the early Silurian Longmaxi mudstone of China’s Sichuan Basin. The PSD data obtained by manual measurement, TWS, and the contribution method are compared. Image analysis finds that the particle sizes of all samples fall in the range of coarse silt to clay, and the average sizes fall in the range of coarse silt to fine silt. The skewness, kurtosis, standard deviation, and other distribution characteristics parameters find minor errors, and the relative error is less than 15%. The Pearson correlation coefficient of the 10th quantile of TWS, black mudstone particle size measure, and manual measurement were calculated, which found R2 values typically ranging between 0.64 and 0.87. Kolmogorov-Smirnov test results find that the data obtained by the three measurement methods are from the same distribution at the level of 0.05. Analytic results find that the method presented is effective, cost-efficient, and could avoid artificial errors.

Mechanical Properties and Binary-Medium-Based Constitutive Model for Coral-Reef Limestone Samples Subjected to Uniaxial Loading

The mechanical and deformation mechanism of coral-reef limestone is vital for the stability and safety of infrastructures built on the ground composed of those materials. Upon loading, strain softening behavior of the coral-reef limestone occurs, usually due to the nonuniform cementation distribution, and the cementation within the samples may break up gradually and reduce the bearing capacity. In order to study their mechanical features, uniaxial compression tests were carried out in this study, and, based on the test results, a binary-medium-based constitutive model was formulated, in which, the sample was idealized, respectively, as the bonded and frictional elements. The bonded elements are composed of strong cementation and may gradually break up to transform into the frictional elements, both of which bear the external loading conjointly. In the new model, the parameters determination method was adopted based on uniaxial compression testing, and comparisons were made between the tested and computed results, which demonstrate that the model can reflect the salient features of coral-reef limestone samples, such as the strain softening and bonding breakage during the loading process. The study can provide a basis for the basic design of coral-reef limestone.

Porosity of municipal solid waste incinerator bottom ash effects on asphalt mixture performance

Dispose and utilization of municipal solid waste incinerator bottom ash (MWSIBA) is one of the imperative issues in environmental protection. The applicability of substitution for natural aggregate with MWSIBA in asphalt mixture was investigated by the performance and micro structure of asphalt mixtures with diverse porosity levels of MWSIBA (varying the replacement percentage). The effects of porosity of MWSIBA on asphalt mixture performance were captured by determination of Marshall stability, tensile strength, dynamic stability and the maximum flexural-tensile strain. The horizontal vibration extraction procedure test was implemented for the heavy metal leaching concentration to evaluate the environmental safety of MWSIBA asphalt mixture. Chemical and micro-morphologic characterization for MSWIBA were conducted to explore the mechanism of moisture damage resistance of asphalt mixture. Results indicated that porosity and replacement rate of MWSIBA exerted impacts on properties of asphalt mixture. The rutting resistance of asphalt mixture decreased due to the addition of MWSIBA, resulting in a reduction in high temperature performance. MWSIBA with porosity no less than 19% was beneficial to the improvement of moisture susceptibility and low temperature performance of asphalt mixture, while high mixing amount of MWSIBA was unfavorable to the properties of asphalt mixture. The water immersion stimulated the hydration reaction in MWSIBA, leading to the formation of C-(A)-S-H gel with strong cementation property, which enhanced the adhesion between MWSIBA and asphalt binder. MWSIBA asphalt mixture presented lower heavy metal concentration and better environmental safety than MSWIBA.