The values of dynamic parameters (DP) for 110 earthquakes with magnitudes MW = 4.7–7.7 that
occurred on Sakhalin in 1978–2024 were obtained. A scalar seismic moment was previously determined for these
earthquakes. To estimate the other DP: the radii of the foci, the shear stress drop, and the reduced seismic energy
a phenomenological approach was used based on the presence of regression, which links the source radius and
the values of the scalar seismic moment for earthquakes within the Sakhalin-Kuril region. The results of the study
were summarized in a data table. Distribution maps of the averaged values of these DP across the studied region
were constructed. Thus, the amount of data on the stress drop and reduced seismic energy for Sakhalin
earthquakes has been significantly increased.
Amirreza Rouhipour, Shahin Kord, Aboozar Soleymanzadeh
Abstract The accurate prediction of the brittleness index (BI) of the rocks is crucial for various geoenergy applications. Mineral-based brittleness index (MBI) is one of the simple methods to calculate the BI of the rocks, but it is associated with errors in various lithologies and mineralogies. The objective of this paper is to develop a new model that improves BI prediction. This new model addresses the limitation of unidimensional analysis of the commonly used MBI in diverse lithologies and mineralogies. To achieve this, MBI was combined with geomechanical information. A dataset of 87 data points, encompassing sedimentary, magmatic, and metamorphic rocks from the GEMex project (Acoculco and Los Humeros region), was utilized. The methodology involved: (1) selecting shear modulus (G), bulk density ( $${\rho }_{b}$$ ), S-wave ( $${V}_{s}$$ ) and P-wave ( $${V}_{p}$$ ) as key geomechanical parameters; (2) conducting data processing, including cleaning, transformation, integration, visualization, and interpretation, to ensure data quality; and (3) employing linear regression to develop the improved BI model. The model demonstrated strong performance, achieving an average of $${\text{R}}^{2}=$$ 95%, MAE of 0.018, and RMSE of 0.05. Notably, the testing data group exhibited the best results: $${\text{R}}^{2}$$ = 97%, MAE = 0.015, and RMSE = 0.02. Furthermore, G was identified as the most influential parameter. This integration of geomechanical data with MBI provides a more robust and accurate approach to BI prediction. This method considers both the mineralogical composition and the mechanical behavior of the rock, leading to a more precise investigation of the rock and representing its key advantage and novelty.
Abstract Integrating petrophysical and geomechanical parameters is an efficient approach to evaluating shale gas reservoir potential. The high cost of corings and their limited number, coupled with time-intensive investigation, led researchers to use this alternative combination approach. In the Jiaoshiba area, from single-pilot well core data and log measurements, petrophysical and geomechanical parameters such as shale volume, total organic carbon, gas content, as well as pore pressure, stress components, and mineral brittleness were first estimated using established methods. In the second phase, based on logging curves, the reservoir electro-facies (EF) classification was performed using the unsupervised multi-resolution graph-based clustering method on a series of twenty wells, identifying five EF with different intrinsic characteristics. Unsupervised analyses were developed using the multilayer artificial neural network while incorporating the K-nearest neighbors and graphical classification algorithms. The results from the first and second phases indicate reservoir richness in organic matter, with the best reservoir exhibited by EF2 and EF3. In addition, effective stress components (S V, S H, and S h) evaluation shows a normal stress regime with hydraulic fracture systems perpendicular to the minimum horizontal stress at each measured depth of the reservoir (S v > S H > S h). This research workflow can efficiently evaluate shale reservoirs with a realistic approach for identifying favorable fracturing positions while reducing errors due to human interference.
Abstract Near miscibility widely exists in carbon dioxide (CO2) injection development projects. However, there is no existing approach to quantify the effect of near miscibility on oil recovery. In this paper, slim tube experiments were conducted to study near miscible region. The oil displacement efficiency curve is divided into immiscibility, near miscibility and miscibility. And three linear function is obtained, respectively. Then, the space between production well and CO2 injection well is discrete to characterize the effect of near miscibility on oil recovery. Then, a new approach is proposed to calculate oil recovery of CO2 displacement in tight oil reservoirs. This approach can calculate oil recovery considering near miscibility. It is found that minimum miscibility pressure (MMP) without considering near miscibility is 4 MPa lower than considering near miscibility. The near miscible pressure range is from 0.77 times to 1 time MMP considering near miscibility. Oil displacement efficiency difference reaches to be the maximum when the pressure is the minimum miscibility pressure without considering near miscibility. The maximum of the oil displacement efficiency difference is 3.4%. The optimal formation pressure considering near miscibility is 5 MPa larger than that without considering near miscibility. The oil recovery considering near miscibility is from 0.9 to 1.3% lower than that not considering near miscibility. It reaches to be the maximum when the pressure is the optimal formation pressure level without considering near miscibility. The maximum of the oil recovery difference is 1.3%.
The findings of environmental history are in the service of ecology and represent an important contribution to the understanding of the sustainable management of land. The aim of this article is to shed light on the relations between the local population and the authorities regarding the afforestation of common land in Komen in the second half of the 19th century and the beginning of the 20th century, placing them in a broader Mediterranean context. The local population was not opposed to afforestation per se, but to the prohibition of usufruct on afforested land, which had major economic consequences for the local population. Authorities did not always take into consideration the annual agricultural processes, local customs, and natural resource needs in their afforestation decisions. The prohibition of usufruct was followed by a shortage of fodder and firewood, which led to forest violations to satisfy demands. Thus, afforestation has undermined the basis of agriculture. In addition, already afforested land remained under common ownership for a relatively long time.
Numeric regional models are necessary to reconstruct the nature and conditions of formation of i geological structures, to obtain ideas about the evolution of different zones of the crust and upper mantle, the evolution of fold and fault dislocations and predicting expression of manifestation of deep structures on earth’s surface. Numeric reconstructions are based on computational dynamics methods, in which rock is represented as highly viscous liquid. «Markers-in-cell» method is one of the implementations of that approach. We propose to accelerate model ported into Python, as compared to Matlab, without rejecting sequential enumeration of markers. It is shown that the solutions can be either code vectorization (refactoring with binary indices instead of enumeration loops and numpy functions) or acceleration of loops by their pre-compilation or parallel computations. The results obtained can be used in the implementation of numeric geological modeling in Python.
Ludmila Maria Fonseca Teixeira, Juliana Troch, Julien Allaz
et al.
Fluid exsolution in magmas is a process that, in many silicic upper crustal reservoirs, starts at relatively low crystallinities (near liquidus), and precedes the precipitation of many ore bodies, including pegmatites. As any magmatic system approaches its solidus, the amount of the exsolved fluid phase increases and becomes progressively dominant over melt, allowing local over pressurization and the generation of pegmatitic pods/dykes. Such pegmatitic bodies show several features that point to both magmatic and hydrothermal environments, linking those realms and providing a unique opportunity to document and understand the magmatic-hydrothermal transition within silicic magmatic systems. We studied the 1.1 Ga classic A-type Pikes Peak granite (Colorado, United States) and one of its many internally-hosted pegmatites, the Wellington Lake pegmatite, to investigate the changes that occur within a granitic system as it crosses its theoretical water-saturated solidus and continues crystallizing beyond it. Textural and geochemical analyses of quartz, plagioclase, and K-feldspar minerals, as well as fluid inclusion studies, demonstrate this magmatic to hydrothermal transition in the granite and the pegmatite. Different thermometers (Ti-in-quartz, 2-feldspars, fluid inclusions) document the temperature evolution of the granitic system, from >850°C for the hottest magmatic minerals to <400°C for the pegmatite core. The magmatic-hydrothermal transition is recorded by plagioclase and quartz rims that yield temperatures well below the traditionally inferred haplogranite solidus. In the pegmatite, the magmatic-hydrothermal transition is observed between the graphic granite wall zone, which shows homogeneous quartz geochemical signatures at near-solidus conditions (700–670°C), and the intermediate zone, which crystallized at much colder temperatures (470–420°C). Although a significant process, our calculations suggest that subsolidus precipitation from exsolved, solute-rich magmatic fluids represent less than 20% of the total volume of the granite.
Abstract Hydraulic fracturing is the key technology in the development of shale gas reservoirs, and it mainly adopts volume fracturing technology to communicate hydraulic fractures with natural fractures to increase the drainage area. In view of the difficulty in characterizing the complex fractures created by multistaged fracturing in horizontal shale gas wells and the immaturity of fracturing optimization design methods, this study first evaluated the stimulation effect of fracturing technology based on treatment data and microseismic data. Then, the fracture characteristics after frac were considered, and a post-frac simulation was studied based on the discrete fracture network (DFN) model and the microseismic monitoring data as constraints. Finally, from the simulation results, an optimal design method of volume fracturing for shale gas was proposed based on the evaluation of the frac effects. The National Shale Gas Demonstration Zone in Zhaotong, Sichuan Basin was used as an example to study the optimal frac design of shale gas wells. The results show that (1) after optimizing the design, the optimal interval range is 50–70 m, the liquid volume of a single stage is 1800–2200 m3, the amount of sand is 80 m~120 t, and the slurry rate is 10–12 m3/min. (2) Two different frac design schemes were implemented in two wells on the same platform, and the production of the optimized design scheme was 14.7% greater than the original scheme. Therefore, the frac optimization design based on evaluating the fracturing effect can better guide the development of subsequent shale gas wells in this area.
meisam Gholipoor, Mehrdad Barati, Ebrahim Tale Fazel
The Lakeh-Siah region is situated in the Central Iran Zone (CIZ), 40 km northeast of Bafq city in the Yazd province. The rocks of the study area belonging to the lower Cambrian; including rhyolite, andesite and pyroclastic surge with porphyry to glomeroporphyric textures. The intrusive igneous rocks occur as stock and dyke and have monzonitic and dioritic composition with intergranular and granular textures. Based on geochemical studies, the rocks under study are calc-alkaline, metaluminous to peraluminous nature. The study apatite shows LREE- enrichment relative to HREE, this is a remarkable feature of the Kiruna- type iron deposits. Also, the enrichment of LILE (such as Rb, Ba, La, U, K and Th) and depletion of HFSE (such as Nb, Ta, Zr and Y) in the host rock, is known as a characteristic of the magmatism in the subduction zones. Based on the concentration of rare and trace elements, the volcanic and to the magmatic arc setting. The overall evidences demonstrate that the primary intrusive rocks belong magma of the rocks have been generated from partial melting of oceanic crust, during the closure of the Proto-Tethys Ocean. Iron oxide- phosphorus magma derived from magmatic differentiation of primary mafic magmas and ascended to higher levels through faults and fractures. Oxygen and hydrogen isotopic study of quartz along with magnetite ore in this deposit and calculation the fluid equilibrium with it shows that the ore- bearing fluid has a magmatic origin.
Kinetic fractionation of 18O and clumped isotopes 13C18O in calcite precipitated to speleothems in cave environments renders the paleo-climatic interpretation of these proxies difficult. Therefore a better understanding of the processes generating the isotope imprint is needed. A heuristic approach is taken to interpret recent data of the fractionations in a cave analogue experiment of calcite precipitation (Hansen et al. 2019) that shows a dependence on experimental precipitation rates, F. An expression, , is derived that is based on uni-directional irreversible precipitation and is valid for large F when the forward rate of precipitation dominates the backward rate of dissolution. In that derivation it is assumed that the kinetic constants of precipitation rates are different for the different isotopologues and that this is also true for their equilibrium concentrations ceq with respect to calcite. The constant, ε, is expressed by the kinetic fractionation where α denote the rate constants of precipitation for the rare and abundant isotopologues. The second constant, λ, is determined by the differing equilibrium concentrations of HCO3- isotopologues with respect to calcite and the pCO2 in the surrounding atmosphere. Fitting this expression to the experimental data one obtains the parameters ε and λ for different temperatures. Regarding these results the temporal evolution of 18δCaCO3 (t) and Δ47(t) is discussed for the experimental conditions and for cave environments. This has implications to the application of 1000lnα18 CaCO3-H2O as a paleo-thermometer. It shows the reason why so many differing calibrations have been reported. These results analogously can be applied also to clumped isotopes 13C18O and the calibration of the Δ47-thermometer with regard to speleothem calcite. In summary, a better understanding of the problems arising in the search for generally valid calibrations of 18O and Δ47 paleothermometers is presented.
Key words: Calcium carbonate, 13C and 18O isotopes, clumped isotopes, kinetic fractionation between HCO3- and calcite, Δ47 paleothermometer.
Kinetična frakcionacija izotopov 18O, 13C in izotopskega skupka 18O13C v sigah in zanesljivost paleotermometrov 18O in Δ47
Kinetična frakcionacija 18O in skupka 13C18O v kalcitu, ki se kot siga odlaga v jamskih okoljih, dela težave pri interpretaciji paleoklime na osnovi teh proksijev. Zato potrebujemo boljše razumevanje procesov, od katerih je odvisen izotopski zapis v sigah. V tem delu s hevrističnim pristopom interpretiramo nedavno pridobljene podatke frakcionacij . Podatki, pridobljeni ob izločanju kalcita v pogojih, podobnih jamskim, kažejo, da na frakcionacijo bistveno vpliva hitrost izločanja kalcita (Hansen et al. 2019). V pogojih, ko je izločanje bistveno hitrejše od raztapljanja, velja zveza . Pri izpeljavi te enačbe upoštevamo, da so kinetične konstante izločanja in ravnotežna konstanta kalcita različne za različne izotopologe. Konstanto ε lahko izrazimo s kinetično frakcionacijo , kjer je α konstanta izločanja za redke oziroma večinske izotopologe. Drugo konstanto λ dobimo iz razlik ravnotežnih koncentracij izotopologov HCO3- glede na kalcit in na atmosferski pCO2 . S prilagajanjem izraza eksperimentalnim podatkom dobimo ε in λ pri različnih temperaturah. To omogoča obravnavo časovne odvisnosti 18δCaCO3 (t) in Δ47(t) pri eksperimentalnih pogojih in v jamskem okolju. Rezultati so pomembni za razumevanje uporabnosti paleotermometra 1000lnα18CaCO3-H2O in hkrati pokažejo na vzrok različnih kalibracij, kot jih zasledimo v literaturi. Rezultate lahko uporabimo tudi za izotopske skupke 13C18O in kalibracijo Δ47- za kalcitno sigo. Članek predstavi nov pogled na iskanje splošno veljavne kalibracije paleotermometrov 18O in Δ47.
Ključne besede: kalcit, izotopa 13C in 18O, izotopski skupki, kinetična frakcionacij a med HCO3- in kalcitom, paleotermometer Δ47.
Abstract Hydraulic fracturing treatment is one of the most efficient conventional matrix stimulation techniques currently utilized in the petroleum industry. However, due to the spatiotemporal complex nature of fracture propagation in a naturally- and often times systematically fractured media, the influence of natural fractures (NF) and in situ stresses on hydraulic fracture (HF) initiation and propagation within a reservoir during the hydrofracturing process remains an important issue. Over the past 50 years of advances in the understanding of HF–NF interactions, no comprehensive revision of the state of the knowledge exists. Here, we reviewed over 140 scientific articles on investigations of HF–NF interactions, published over the past 50 years. We highlight the most commonly observed HF–NF interactions and their implications for unconventional oil and gas production. Using observational and quantitative analyses, we find that numerical modeling and simulation is the most prominent method of approach, whereas there are less publications on the experimental approach, and analytical method is the least utilized approach. Further, we suggest how HF–NF interactions can be monitored in real time on the field during a pre-frac test. Lastly, based on the results of our literature review, we recommend promising areas of investigation that may provide more profound insights into HF–NF interactions in such a way that can be directly applied to the optimization of fracture-stimulation field operations.
Abstract Supported ionic liquid (IL) catalysts [C n mim]3PMo12O40/Am TiO2 (amorphous TiO2) were synthesized through a one-step method for extraction coupled catalytic oxidative desulfurization (ECODS) system. Characterizations such as FTIR, DRS, wide-angle XRD, N2 adsorption–desorption and XPS were applied to analyze the morphology and Keggin structure of the catalysts. In ECODS with hydrogen peroxide as the oxidant, it was found that ILs with longer alkyl chains in the cationic moiety had a better effect on the removal of dibenzothiophene. The desulfurization could reach 100% under optimal conditions, and GC–MS analysis was employed to detect the oxidized product after the reaction. Factors affecting the desulfurization efficiencies were discussed, and a possible mechanism was proposed. In addition, cyclic experiments were also conducted to investigate the recyclability of the supported catalyst. The catalytic activity of [C16mim]3PMo12O40/Am TiO2 only dropped from 100% to 92.9% after ten cycles, demonstrating the good recycling performance of the catalyst and its potential industrial application.
Abstract The production from oil and gas reservoirs is greatly affected by rock and fluid properties of the porous rock. Capillary pressure (P c) and relative permeability (k r) are two important properties employed in the mathematical simulation reservoirs for predicting oil recovery from underground hydrocarbon resources. In this study, various core-flood experiments were performed using different tight carbonate rock samples for oil–water and oil–gas systems. The objective of this research is to investigate the multi-phase flow functions (k r and P c) in tight formations. The k r curves of each sample were obtained by two different mathematical methods: the history-matching (ant colony optimization) technique and analytical method (JBN). The comparison between the relative permeability of the history-matching technique with that of the JBN method revealed a significant discrepancy between them. The modeling of an experiment using k r of JBN revealed a significant difference between experimental and simulation oil production, whereas the relative permeability of history matching accurately reproduced the experimental oil recovery. This observation highlights the inadequacy of the JBN technique for determination of relative permeability in particular in the tight rock where capillary forces are important. In addition to the relative permeability, the capillary pressure values as a function of saturation were estimated from core-flood tests using a history-matching technique. The comparison between oil–water capillary pressures obtained from centrifuge tests with those of core-flood experiments depicted good agreement, whereas the capillary pressure of oil–gas system measured from core-flood tests was considerably different from centrifuge experiment results. This outcome demonstrated that the capillary pressure obtained from centrifuge experiments in some cases may not be representative of dynamic capillary pressure governing the multi-phase flow in porous media.
Abstract. Chemical equilibration between two different assemblages (peridotite-type and gabbro/eclogite-type) of variable initial size assuming few different initial compositions has been determined using certain mass and reactions constraints and thermodynamic principles. The pattern that emerges suggests that mass transfer between the two sub-systems defines two petrological assemblages that separately are maintained in local thermodynamic equilibrium. In addition, when two assemblages previously equilibrated together in a certain mass ratio are rearranged assuming a different initial ratio, no mass transfer occurs and the two sub-systems remain unmodified. By modeling the chemical equilibration results of several systems it is possible to provide a quantitative framework to determine the chemical and petrological evolution of two assemblages from an initial state, in which the two are separately in chemical equilibrium, to a state of equilibration of the whole system (sum of the two sub-systems). Assuming that the local Gibbs energy variation follows a simple diffusion couple model, a complete petrological description of the two systems can be determined over time and space. Since there are no data to constrain the kinetic of the processes involved, the temporal and spatial scale is arbitrary. Nevertheless a 1-D static model shows how chemical equilibration is controlled by the size of the two sub-systems. As the initial size of the first assemblage (peridotite-like) increases, the differences between the initial and the final equilibrated stage becomes smaller, while on the opposite side the difference increases. A simplified 2-D dynamic model in which either one of the two sub-systems is allowed to move with a prescribed velocity, shows that after an initial transient state, the moving sub-system tends to preserve its original composition defined at the entry side. The other sub-system instead evolves towards a large compositional difference from the starting assemblage. The results appear to be the same varying the initial proportion of the two assemblages, which simplify somehow the development of potential tools for predicting the chemical equilibration process from real data and geodynamic applications. Four animations and data sets of three 1-D and two 2-D numerical models are available following the instructions in the supplementary material.
Abstract In deep-rod pumping wells, polished rod load tends to be very high and even exceeds the operating range of the pumping unit. To tackle the problem, mainly four rod load reduction techniques have been designed till now. They are side-flow pump, rod load reducer, fiberglass sucker rod and deep pumping with small-diameter pump. However, some of them still cause certain problems when put into use. That indicates the fundamental mechanisms of these techniques have not yet been fully studied. In this paper, on the basis of conventional polished rod load calculation models, the new calculation models for these techniques are respectively established. The rod load reduction effects are comparatively analyzed by calculation. The results indicate that the differences in mechanisms lead to different reduction effects. Side-flow pump and deep pumping with small-diameter pump can largely reduce the liquid pressure load, but its reduction effect for the polished rod load is very limited. On the contrary, fiberglass sucker rod can greatly reduce the polished rod load by decreasing the weight of the sucker rod. Rod load reducer does not change the previous load; instead, it can create an additional reduction force. The potential disadvantages are also discussed. When using a side-flow pump, the resistance on the plunger caused by the liquid pressure would increase. This resistance may cause the sucker rod to bend when it is moving downwards. Deep pumping with small-diameter pump needs to use very small pump in order to get a relatively good reduction effect, so its application is limited. These disadvantages should be considered in practical application.