Log Response Research Articles

A Method for Correction of Shoulder-Bed Effect on Resistivity Logs Based on a Convolutional Neural Network

Abstract —Shoulder beds may have a significant effect on the resistivity log responses. This problem is especially acute in studies of complex strata composed of thin beds with contrasting properties. Different approaches to taking account of the shoulder-bed effect on logging signals are known, such as correction charts, deconvolution operations, and using advanced algorithms of numerical data inversion, which allow one to consider the vertical inhomogeneity of the section. The best result is achieved using the inversion toolkit, but the high labor- and resource-intensiveness of the approach limits its widespread use. The deconvolution approach does not have these disadvantages, but it does not take into account the influence of radial changes in the medium properties on the shapes of measured signals.The possibility of using artificial neural networks (ANN) to increase the vertical resolution of the measured logging data is explored. We assume the existence of a deconvolution-like transformation in which change in the medium properties in the radial direction is also considered. In this case, we can find its approximation using a neural network. The approach is demonstrated by creating a transformation algorithm for the high-frequency electromagnetic logging (VIKIZ) sounding tool, which is widely used in the CIS countries for petroleum exploration. The developed algorithm has been tested on the VIKIZ logs from the Fedorovskoe oilfield (Latitudinal Ob’ region).

Petrophysical Properties and Reservoir Assessment of Mishrif Formation in Eridu oil field, Southern Iraq

This study is achieved in the local area of the Eridu oil field, where the Mishrif Formation is considered the main productive reservoir. The Mishrif Formation was deposited during the Cretaceous period in the secondary sedimentary cycle (Cenomanian-Early Turonian as a part of the Wasia Group, a carbonate succession widespread throughout the Arabian Plate. The Mishrif Formation already have been evaluated in terms of depositional environments and their diagenetic processes. Here, it will test the previous conclusions with petrophysical properties delineated by using well logging. The results show there is a fully matching with two reservoir units (MA and MB). Dissolution and primary porosity are responsible for forming a variety of large porosity types. These porosity types have preserved the hydrocarbons in commercial quantities. MA and MB reservoir units show low gamma ray and high to moderate total and effective porosities values. The water saturation Sw in the upper unit (MA) is very high in generally to become water-bearing zone. This appears in all studied wells except in the E-NE part, characterized by patches area of moderate water saturation. In contrast, the lower unit (MB) is characterized by high values of hydrocarbon saturation (Sh) except for some areas in the middle of the studied field. Cap rocks (CR1 and CR2) represents rock unit with low porosity and permeability due to the main components of these units. It contains lime mudstone with log response of this cap rocks indicates high gamma-ray peak value. Compaction and dolomitization are responsible for low porosity and permeability in this type of rock unit.

Prediction of lamina structure and reservoir quality in shale using well logs: The Cretaceous Qingshankou Formation, Gulong Sag, Songliao Basin, China

Lamina structure is determined by composition, thickness, continuity, and mineral assemblage. Reservoir quality in oil shale reservoirs is determined by lamina structure, which controls hydrocarbon accumulation and migration. The prediction and evaluation of multi-scale lamina structures using geophysical well logs is challenging. Recent studies demonstrate that the lamina structure classification may be based on core observation and core analysis. However, there are no corresponding high-resolution geophysical logging methods to identify and categorize lamina structure continuously in a single well. Here, an experimental approach, involving an integrated analysis of cores, thin sections, well logs such as slabs and button conductivity curves of image logs (up to 5 mm vertical resolution), is used to characterize lamina structure. T1-T2 (T1, longitudinal relaxation time, and T2, transverse relaxation time) maps of nuclear magnetic resonance (NMR) logs are applied to clarify the relationships between the lamina structure, reservoir quality, and oil-bearing properties. Results demonstrate how lamina structure in shale can be divided into three types: laminated rocks, layered rocks, and massive rocks, according to observation of core at the lamina scale. The thickness of individual lamina is less than 0.01 m in the laminated rocks, and the layered rocks have bundles of genetically related laminae thickness ranging between 0.01 m and 0.1 m. In massive rocks there is no visible layering. The well log response patterns of the three types of lamina structure are established so that the distribution of lamina structure can be predicted in a single well via well logs. Results show that the oil-bearing shale intervals are dominated by laminated rocks and layered rocks, accounting for 90% of the studied Qingshankou Formation. In addition, the layered rocks play an important role in improving reservoir quality and the laminated rocks present moderate reservoir quality. The massive rocks show poor reservoir quality. Moreover, an increased proportion of felsic mineral content favors increased oil potential in oil shale reservoirs. The method is generally applicable and is of value in developing predictive indicators of subsurface reservoir sweet spots in shale oil and gas exploration and development.

Expanding Measuring Range of LWD Resistivity Instrument in High Permittivity Layers

The effective measuring range of an electromagnetic wave resistivity instrument used in logging while drilling (LWD) is small, and the resistivity measurement is greatly influenced by the dielectric constant, especially in high-dielectric-constant formations. In this paper, the response characteristics of the instrument under a high dielectric constant are investigated by a numerical simulation algorithm, and the resistivity conversion method is determined. The results show that the higher the working frequency of the electromagnetic wave resistivity instrument while drilling, and the greater the formation of background resistivity, the greater the influence of the dielectric constant on the logging response. The existence of the dielectric constant will cause the phase shift and amplitude attenuation of the measured signal to migrate, and this migration is proportional to the formation resistivity and the dielectric constant. According to this rule, the resistivity–permittivity response library is established, and the formation permittivity is calculated by the inversion of the library. On the basis of obtaining the formation permittivity, the migration of the logging signal permittivity is corrected, the influence of the dielectric constant is eliminated, and the measuring precision and measuring range of the instrument in the high-dielectric-constant formation are enlarged.

Classification and well-log identification of lithofacies of continental shale oil reservoirs in Chang 7-3 submember of the Triassic Yanchang Formation in the Longdong area of the Ordos Basin, China

The division and identification of lithology and lithofacies are very important in exploration and development of oil and gas reservoirs. Information on lithofacies determines the development modes and provides the favorable “sweet spot” intervals of shales. The Chang 7-3 submember of the Triassic Yanchang Formation in the Longdong area of the Ordos Basin is an important shale formation in China. Core photos, cast thin sections, and log response characteristics were used to clarify the development and distribution characteristics of the various lithofacies in this formation. The lithofacies of target intervals are classified into fine-grained sandy debrite, silty to fine-grained sandy turbidite, fine-grained sandy slump, semideep to deep lacustrine mudstone, and deep lacustrine shale. Furthermore, the conventional and microresistivity imaging log response characteristics of different lithofacies are analyzed. Compared with other lithofacies, deep lacustrine shale facies are characterized by high gamma ray (GR), high compensated neutron log (CNL), high acoustic log (AC), and low-density (DEN) log values. Crossplots of GR-AC, DEN-CNL, and DEN-AC are proposed to identify most of the lithofacies, and a criterion was established for use of well logs to characterize the lithofacies. Finally, a method joining conventional logs and microresistivity imaging log data was applied to field wells, achieving the very high accuracy rate of 88%. The distribution maps of different lithofacies thickness in the study area are obtained. Deep lacustrine shale facies have the widest development area and many thickness centers. Accurate and effective identification of lithofacies indicates that within the Ordos Basin, there is an area of approximately 20,000 km2 with shale thickness of greater than 6 m, providing an important basis for shale oil exploration in the study area.

Well logging evaluation of fine-grained hydrate-bearing sediment reservoirs: Considering the effect of clay content

Hydrate reservoirs are different from the host reservoirs of all other fossil energy sources because the characteristics of hydrate reservoirs are generally controlled by deep-sea fine-grained sedimentation. In such reservoirs, the reliability of the classical logging evaluation models established for diagenetic reservoirs is questionable. This study used well W8 in the Qiongdongnan Basin to explore the clay content, porosity, saturation, and hydrate-enriched layer identification of a logging-based hydrate reservoir, and it was found that considering the effect of the clay content on the log response is necessary in the logging evaluation of hydrate reservoirs. In the evaluation of clay content, a method based on the optimization inversion method can obtain a more reliable clay content than other methods. Fine-grained sediment reservoirs have a high clay content, and the effect of clay on log responses must be considered when calculating porosity. In addition, combining density logging and neutron porosity logging data can obtain the best porosity calculation results, and the porosity calculation method based on sonic logging predicted that the porosity of the studied reservoir was low. It was very effective to identify hydrate layers based on resistivity, but the clay distribution and pore structure will also affect the relationship between resistivity, porosity and saturation, and it was suggested that the factors effecting the resistivity of different layers should be considered in the saturation evaluation and that a suitable model should be selected. This study also considered the lack of clarity of the relationships among the lithology, physical properties, hydrate-bearing occurrence properties, and log response properties of hydrate reservoirs and the lack of specialized petrophysical models. This research can directly help to improve hydrate logging evaluation.

Mismatches in thermal performance between ectothermic predators and prey alter interaction strength and top-down control

Climate change can alter predator-prey interactions when predators and prey have different thermal preferences as temperature change can exacerbate thermal mismatches (also called thermal asymmetry) with population-level consequences. We tested this using micro-arthropod predators (Stratiolaelaps scimitus) and prey (Folsomia candida) that differ in their temperature optima to examine predator-prey interactions across two temperature ranges, a cool (12 and 20°C) and warm (20 and 26°C) range. We predict that the lower thermal preference and optimum in F. candida will alter top-down control (i.e., interaction strength) by predators with interaction strength being strongest at intermediate temperatures, coinciding with F. candida thermal optimum. Predators and prey were placed in mesocosms, whereafter we measured population (predator and prey abundance), trait-based (average predator and prey body mass, and prey body length distribution), and predator-prey indices (predator-prey mass ratio (PPMR), Dynamic Index, and Log Response Ratio) to determine how temperature affected their interactions. Prey populations were the highest at intermediate temperatures (average temperature exposure: 16-23°C) but declined at warmer temperatures (average temperature exposure: 24.5-26°C). Predators consistently lowered prey abundances and average prey mass increased when predators were added. Top-down control was the greatest at intermediate temperatures (indicated by Log Response Ratio) when temperatures were near or below the thermal optimum for both species. Temperature-related prey declines negated top-down control under the warmest conditions suggesting that mismatches in thermal performance between predators and their prey will alter the strength and dominance of top-down or bottom-up forces of predator-prey interactions in a warmer world.

Machine-Learning-Based Convolution Method for Fast Forward Modeling of Induction Log

We built a convolution model using machine learning (ML) to calculate induction log responses for one-dimensional (1D) earth models. Compared to analytical forward modeling, the convolution model is extremely fast. ML-based convolution finds accurate induction tool responses from an earth model with layer resistivity and layer boundaries. For a unit induction tool 2C40, the 101-point, 50-ft window convolution model works satisfactorily for a well deviation angle of 60.

Seismic prediction of shale reservoir quality parameters: A case study of the Longmaxi–Wufeng formation in the WY area

Shale is a crucial natural gas resource, attracting global exploration and development interest. China has abundant shale gas resources that will drive future oil and gas exploration advances by increasing reserves and production. The WY shale gas field is the most productive and has the greatest potential for exploration and development. This study analyzed high-quality shale logging response characteristics and drilling logging, seismic, and analytical test data in the WY area to establish a rock physical model of seismic attribute parameters and shale reservoir quality parameters. Seismic elastic parameters were converted into indicators that directly reflect shale reservoir quality, such as total organic carbon (TOC), high-quality reservoir thickness, porosity, brittleness index, and crack development strength. Corresponding regression equations were established to predict quality parameters.The results showed that shale reservoir quality parameters have a good correlation with seismic parameters. The TOC distribution ranged from 2% to 5% in the study area and was generally high in the north but low in the south. The high-quality shale reserve had a thickness of over 40 meters, and except for the northwest region, the porosity was nearly over 4%. The overall brittleness of the study area was favorable, and the brittleness index was over 35%, which is suitable for network fractures formation in subsequent fracturing operations. The anisotropy of shale in S1l1I was small, and the overall fractures were underdeveloped in the study area. Drilling verifications showed that the prediction results of the quality parameters of high-quality shale reservoirs were consistent with actual drilling test results with high reliability. This study provides guidance for comprehensive prediction of sweet spots and subsequent fracturing and well location deployment.In summary, this study provides valuable insights into shale gas exploration and development in the WY area by establishing a rock physical model, predicting quality parameters, and offering guidance for fracturing and well location deployment.

Quantitative characterization of fracture spatial arrangement and intensity in a reservoir anticline using horizontal wellbore image logs and an outcrop analogue

Using image logs from horizontal wells in the asymmetric East Painter Reservoir anticline in Wyoming, scanlines and petrographic observations from nearby outcrops, and methods that allow statistical quantification of fracture spatial arrangement patterns (including clustering), we show that in early Jurassic Nugget Formation sandstone degree of clustering and intensity of fractures varies with structural position. In the backlimb, fractures are markedly more clustered than random, and hierarchical and regularly spaced clusters are present, but intensity is low. In the forelimb, arrangements are mostly indistinguishable from random, but intensity is high. Based on image log response, the backlimb contains a higher proportion of open fractures, although the forelimb has greater numbers of open fractures. Spatial arrangement and intensity patterns are similar in a forelimb outcrop. Petrography reveals that quartz seals fractures less than 0.15 mm wide. Wider fractures are open with quartz rinds or are quartz lined and sealed with calcite or filled by quartzose cataclasite. The proportion of open fractures depends on quartz and calcite deposits and closure by reactivation (shearing) of pre-existing quartz-lined fractures. Based on increased abundance and greater strike dispersion, results suggest that in forelimbs, high fracture intensities reflect shear on preexisting fractures, possibly resulting in more numerous but less spatially correlated open fractures. The most prolific gas and water production wells are in the backlimb, suggesting that clustered but sparse quartz-lined open fractures are more effective fluid conduits than closely spaced partly damaged/sheared arrays.

Effects of photovoltaic power station construction on terrestrial ecosystems: A meta-analysis

The rapid increase in construction of solar photovoltaic power stations (SPPs) has motivated ecologists to understand how these stations affect terrestrial ecosystems. Comparing study sites, effects are often not consistent, and a more systematic assessment of this topic remains lacking. Here, we evaluated the effects of SPP construction on carbon emissions, edaphic variables, microclimatic factors and vegetation characteristics in a meta-analysis. We employed log response ratios (as effect sizes) to assess how control plots differed from those beneath solar photovoltaic panels. We found that SPP construction decreased the local air temperature and photosynthetically active radiation, while increasing air humidity, especially in grasslands. Furthermore, plant aboveground biomass and vegetation cover were also enhanced by SPP construction in grassland ecosystems. In farmland ecosystems, photovoltaic panel installation increased plant aboveground biomass, soil available phosphorus and soil pH, while reducing CO2 flux, plant species richness and vegetation cover in woodlands. Thus, while SPP construction had profound ecological impacts in terrestrial ecosystems, the direction and strength of these effects were largely dependent on ecosystem type. Most studies of SPP construction to date have focused on local microclimatic and plant diversity effects, but few studies have examined effects on ecosystem functions and services. Future assessments are needed of both the benefits and disbenefits of SPP construction across different ecosystems, to improve SPP site selection and adaptive management.

Fracture characterization of Asmari Formation carbonate reservoirs in G Oilfield, Zagros Basin, Middle East

The Asmari Formation in the G oilfield on the Iran-Iraq border is a fractured-porous multi-lithology mixed reservoir, for which fracture is an important factor affecting oil productivity and water cut. The characterization and modeling of fractures in the carbonate reservoir of G oilfield are challenging due to weak conventional well log responses of fractures and a lack of specific logs, such as image logs. This study proposes an integrated approach for characterizing and modeling fractures in the carbonate reservoir. The features, formation mechanism, influencing factors, and prediction methods of fractures in the Asmari Formation carbonate reservoirs of G oilfield were studied using core observation, thin section, image log, cross-dipole acoustic log (CDAL), geomechanics numerical simulation (GNS), and production data. According to CDAL-based fracture density interpretation, GNS-based fracture intensity prediction between wells, and DFN-based rock fracture properties modeling, the quantitative fracture characterization for G oilfield was realized. This research shows that the fractures in the Asamri Formation are mainly medium-to high-angle shear fractures. The substantial compression stress during the Miocene played a major role in the formation of the prominent fractures and determined their trend in the region, with primary trends of NNW-SSE and NNE-SSW. The fracture distribution has regularity, and the fractures in zone A dolomites are more highly developed than that in zone B limestones vertically. Horizontally, fractures intensity is mainly controlled by faults and structural location. The results of this study may benefit the optimization of well design during field development. From 2019 to 2021, three horizontal wells pilot tests were deployed in the fractures belt in zone A, and these fractures prominently increased the permeability of tight dolomite reservoirs. The initial production of the wells is four to five times the average production of other wells in the area, showing a good development effect. Meanwhile, the updated numerical simulation validates that the history match accuracy of water cut based on the dual-porosity model is significantly improved, proving the fracture evaluation and prediction results to be relatively reliable and applicable.

Evaluation Techniques for Shale Oil Lithology and Mineral Composition Based on Principal Component Analysis Optimized Clustering Algorithm

Shale oil reservoirs are characterized by complex lithology, complex mineral composition and strong heterogeneity. This causes great difficulty in lithologic evaluation. In this paper, a method of lithology identification is proposed by means of intersection plot method and machine learning method, and lithology evaluation is carried out by combining the calculation of mineral content with a multi-mineral optimization model. The logging response characteristics of five lithologies are analyzed by using the logging curves selected by principal component analysis (PCA) discriminant analysis. In lithology identification, the system clustering algorithm is selected to identify shale oil reservoir lithology through layer-by-layer subdivision of sample lithology classification. Logging data has high vertical resolution and good continuity, and mineral prediction using logging data can ensure high accuracy. In this paper, the method of calculating mineral content by using multi-mineral optimization model has achieved good results in practice.

Overpressure Generation and Evolution in Deep Longmaxi Formation Shale Reservoir in Southern Sichuan Basin: Influences on Pore Development

Strong overpressure conditions are widely distributed in the deep Longmaxi Formation (Fm) shale reservoirs in the Southern Sichuan Basin, with pressure coefficients ranging from 1.75 to 2.45. Overpressure plays a positive role in the high yield of shale gas, but a detailed study of its generation mechanism, evolution history, and potential impact on pore development is still lacking. This study’s evidence from theoretical analysis and the logging response method indicates that hydrocarbon generation expansion is the main generation mechanism for strong overpressure. Through the combined analysis of basin modeling, inclusions analysis, and numerical simulation, pressure evolution at different stages is quantitatively characterized. The results show that, during the shale’s long-term subsidence process, the shale reservoir’s pressure coefficient increased to 1.40 because of oil generated by kerogen pyrolysis. Then it increased to 1.92 due to gas generated by residual oil cracking. During the late strong uplift process of the shale, temperature decrease, gas escape, and stratum denudation caused the pressure coefficient to first decrease to 1.84 and then increased to 2.04. Comparing pore characteristics under different pressure coefficients indicates that higher pressure coefficients within shale reservoirs contribute to the maintenance of total porosity and the development of organic macropores, but the influence on the morphology of organic pores is negligible. These results will provide the scientific basis for optimizing sweet spots and guiding shale gas exploration in the study area.

Regenerative fertilization strategies for climate-smart agriculture: Consequences for greenhouse gas emissions from global drylands

Cultivated drylands are significant sources of greenhouse gases (GHGs), with declining yields. Regenerative practices are vital to achieve joint goals of boosting yields and mitigating GHGs emissions. Nevertheless, studies usually consider crop yields and soil properties, often lacking quantitative analysis of GHGs. This meta-analysis used log response ratio (lnRR) to perform effect size statistics; assessing impacts of major regenerative (manure, biochar, and two integrated applications) and inorganic fertilizers on GHGs emissions. The results reveal that GHGs emissions were increased by fertilizer or manure addition, but biochar decreased GHGs emissions, with greatest benefit at 50 t ha−1. Combining biochar or manure application with fertilizer emitted CO2 and/or N2O. Applying biochar alone led to 144% reduction in global warming potential (GWP). Paddy-rice with fertilizer emitted N2O and CH4, whereas these were mitigated by wheat with biochar. Fine-textured soils with manure emitted all three GHGs, whereas biochar with coarse-textured soils reduced emissions. Medium-textured soils had reduced N2O (18%) and CH4 (25%) emissions with integrated biochar and fertilizer. CO2 and N2O emissions were highest for neutral and acidic soils with fertilizer but lowest for alkaline soils after biochar application. Soil C:N ratios affected the best strategy to minimize GHGs: for high C:N ratio, fertilizer or manure should be avoided, in favour of biochar. Yet integrated biochar and fertilizer should be avoided for soils with low C:N ratio. We conclude that regenerative strategies using manure risk converting global drylands into major GHGs emitters. However, strategies incorporating biochar could mitigate dryland GHGs emissions and minimize GWP.

A new semianalytical algorithm for rapid simulation of triaxial electromagnetic logging responses in multilayered biaxial anisotropic formations

A set of compact and stable formulas are developed for the computation of triaxial electromagnetic (EM) logging responses in multilayered formations with biaxial anisotropy. These formulas are based on a new global amplitude propagator matrix (GAPM) algorithm, which derives the amplitudes of upgoing/downgoing waves at the boundaries rather than the reflection/transmission coefficients of each layer. The kernel of the GAPM algorithm is assembling the local continuity equations into a global linear system, which has addressed the notorious overflow problems commonly encountered by the traditional coefficient propagator matrix approach. To fast and accurately convert the EM fields from the spectral domain into the spatial domain, an efficient twofold inverse Fourier transform (IFT) technique is established for the computation of triaxial EM logging responses. Two main techniques are developed to significantly improve the computation accuracy and speed of IFT. On the one hand, the spectral fields at the first integral quadrant can be used to express the fields at the other three quadrants. Consequently, the original twofold infinite integral is analytically simplified to a semiinfinite one and the computation cost can be reduced by three-fourths. On the other hand, a two-level subtraction scheme is developed to reduce the integral singularity. The first-level subtraction is achieved by separating the primary fields from the total fields. The second-level process includes subtracting the spectral scattered fields of an equivalent transverse isotropic (TI) layered medium, integrating the residual fields, and computing the spatial fields of the TI model. The subtractions on the primary and scattered fields can make the integral convergence increase by more than 10 orders of magnitude in favorable conditions. Numerical experiments demonstrate that the new semianalytical formulas are well suited for any dipping angle and an arbitrary number of layers, as well as for thin and thick formations. The modeling method is efficient and robust, which can provide a fast simulator for the interpretation of triaxial EM logging data.

Electric field and potential distribution in layered homogeneous borehole fluids and its logging responses of resistivity logging through casing

The resistivity logging through casing is an important logging instrument to carry out formation evaluation in the production wells. The transmission line equation (TLE) is a useful tool to solve the huge resistivity differences between metal casing and formation. Except for the casing, borehole fluids (e.g., mud, water, oil and gas) still could affect the logging responses of the resistivity logging through casing, which has not been studied well. Furthermore, the conventional TLE cannot be applied to investigate the current and potential distributions in borehole fluids. A suitable algorithm needs to be studied to calculate the influences of borehole fluids on logging responses. In this paper, we propose a modified TLE, which includes the formation information outside the casing and borehole fluids. Then, the analytical solution of the potential distribution on casing wall is derived using the modified TLE. For the infinite casing case, the current and potential distributions in borehole fluids are further derived based on the calculated potential distributions on casing wall and characteristic of the axial symmetry. In addition, the logging responses of resistivity logging through casing are calculated and compared. Through the numerical modeling, a new phenomenon is discovered that the voltage is low at the regions where casing contact with electrode and different borehole fluids. A microscopic qualitative explanation is given using the ion damping oscillation model of a reflective cavity to explain the existence of these low voltage regions. Furthermore, the contacts of borehole fluids are observed on the logging responses of resistivity through casing.

Comparing Interventions With Speech-Generating Devices and Other Augmentative and Alternative Communication Modes: A Meta-Analysis.

Optimal augmentative and alternative communication (AAC) systems for children with complex communication needs depend in part on child characteristics, child preferences, and features of the systems themselves. The purpose of this meta-analysis was to describe and synthesize single case design studies comparing young children's acquisition of communication skills with speech-generating devices (SGDs) and other AAC modes. A systematic search of published and gray literature was conducted. Data related to study details, rigor, participant characteristics, design information, and outcomes were coded for each study. A random effects multilevel meta-analysis was performed using log response ratios as effect sizes. Nineteen single case experimental design studies with 66 participants (M age = 4.9 years) met inclusion criteria. All but one study featured requesting as the primary dependent variable. Visual analysis and meta-analysis indicated no differences between use of SGDs and picture exchange for children learning to request. Children demonstrated preferences for and learned to request more successfully with SGDs than with manual sign. Children who preferred picture exchange also learned to request more easily with picture exchange than with SGDs. Young children with disabilities may be able to request equally well with SGDs and picture exchange systems in structured contexts. More research is needed comparing AAC modes with diverse participants, communication functions, linguistic complexity, and learning contexts. https://doi.org/10.23641/asha.22111181.

Meta-analytic evidence that allelopathy may increase the success and impact of invasive grasses.

In the grass family, a disproportionate number of species have been designated as being invasive. Various growth traits have been proposed to explain the invasiveness of grasses; however, the possibility that allelopathy gives invasive grasses a competitive advantage has attracted relatively little attention. Recent research has isolated plant allelochemicals that are mostly specific to the grass family that can breakdown into relatively stable, toxic byproducts. We conducted a meta-analysis of studies on grass allelopathy to test three prominent hypotheses from invasion biology and competition theory: (1) on native recipients, non-native grasses will have a significantly more negative effect compared to native grasses (Novel Weapons Hypothesis); (2) among native grasses, their effect on non-native recipients will be significantly more negative compared to their effect on native recipients (Biotic Resistance Hypothesis); and (3) allelopathic impacts will increase with phylogenetic distance (Phylogenetic Distance Hypothesis). From 23 studies, we gathered a dataset of 524 observed effect sizes (delta log response ratios) measuring the allelopathic impact of grasses on growth and germination of recipient species, and we used non-linear mixed-effects Bayesian modeling to test the hypotheses. We found support for the Novel Weapons Hypothesis: on native recipients, non-native grasses were twice as suppressive as native grasses (22% vs 11%, respectively). The Phylogenetic Distance Hypothesis was supported by our finding of a significant correlation between phylogenetic distance and allelopathic impact. The Biotic Resistance Hypothesis was not supported. Overall, this meta-analysis adds to the evidence that allelochemicals may commonly contribute to successful or high impact invasions in the grass family. Increased awareness of the role of allelopathy in soil legacy effects associated with grass invasions may improve restoration outcomes through implementation of allelopathy-informed restoration practices. Examples of allelopathy-informed practices, and the knowledge needed to utilize them effectively, are discussed, including the use of activated carbon to neutralize allelochemicals and modify the soil microbial community.

Research and application of high-resolution micro-cylindrically focused logging tool

The unknown nature and complexity of non-uniform formations cause new difficulties and challenges to the accurate detection of electrical instruments in shallow formations. The micro-cylindrically focused logging tool (MCFL) can provide three original measurement curves, RB0, RB1, and RB2, with different detection depths, which reflect the flushing zone resistivity, mudcake resistivity, and mudcake thickness. In this study, the finite element method was used to model and analyze the micro-cylindrically focused logging tool tool in a three-dimensional non-uniform medium model. By converting the partial differential equation into a generalized polar problem, the logging response characteristics of the micro-cylindrically focused logging tool tool at different detection depths and ranges, mudcake thicknesses, flush zones, and mudcake resistivity contrasts were investigated. Inverse processing of the micro-cylindrically focused logging tool data using the least-squares method was used to obtain the flush zone resistivity, mudcake resistivity, and mudcake thickness, based on which the micropotential and microgradient curves were synthesized. In addition, a digital focusing method was proposed to improve the focusing accuracy and flexibility of the instrument, enhancing the performance of the micro-cylindrically focused logging tool. The optimized design of the focusing method significantly improved the detection performance of the pole plate. This plays an important role in the evaluation of thin layers and oil-water reservoirs.