Field Case Research Articles

Multichannel seismic attenuation compensation and interpolation with curvelet sparse constraint of frequency-wavenumber spectrum

Abstract High-resolution exploration is hampered by seismic attenuation, caused by the viscosity and heterogeneity of underground media. Conventional single-channel attenuation compensation methods can increase the corresponding vertical resolution partially. While the lateral continuity of compensated seismic data is always ignored and the noise resistance can be improved. Therefore, multichannel attenuation compensation methods were proposed, including the algorithm with sparse curvelet coefficient constraint of the time-space (t-x) data. However, nonstationary seismic data may be affected by irregular missing traces in field cases, which severely degrades its lateral continuity and negatively affects the performance of multichannel attenuation compensation. Therefore, we concentrate on simultaneous multichannel attenuation compensation and missing trace interpolation in a unified framework. Based on the inversion framework of sparsity promotion, we propose an approach for simultaneous multichannel compensation and interpolation, utilizing sparse curvelet coefficient constraint of the recovered principal frequency-wavenumber (f-k) spectrum. The size of the principal f-k spectrum is reduced by at least half compared with that of the corresponding t-x band-limited data. It significantly reduces the computational expense of curvelet transform-based processing. Synthetic and field data experiments validate the effectiveness of the proposed method in efficiency improvement with consistent performance when compared to the multichannel method with sparse curvelet coefficient constraint of the t-x data in improving the vertical resolution and lateral continuity. Furthermore, we have discussed a potential acceleration strategy based on random sampling in the normal compensation issue.

A Coupling Model of Gas–Water Two-Phase Productivity for Multilateral Horizontal Wells in a Multilayer Gas Reservoir

A series of complex horizontal wells have been implemented in challenging gas reservoirs. Multilateral horizontal well technology can be used in multilayer gas reservoirs, facilitating the expansion of the gas drainage area and enhancing productivity. Accurate productivity calculations for multilateral wells in multilayer reservoirs are essential for effective reservoir development. However, there have been few studies in this area. This paper introduces a coupling model for calculating the gas–water two-phase productivity of multilateral wells in multilayer reservoirs, based on the principles of conformal transformation and superposition of potential functions. The accuracy of the model is validated by obtaining the distribution of flow along the horizontal wellbore through numerical simulation cases. The results from the field case and sensitivity analysis indicate that the pressure difference increases nonlinearly from the toe to the heel, and the productivity of multilateral wells decreases as the gas–water ratio increases. The method proposed in this paper is applicable for calculating the productivity of multilateral wells in multilayer reservoirs.

The Evaluation of Written Tests at Nurussyifa Islamic Kindergarten to Support Merdeka Curriculum

Early childhood is the nation's next generation whose development and growth we must maximize. During this golden age, children receive stimulation from the environment at home, at school and in the community. At school, teachers provide stimulation to children through learning activities according to the kurikulum merdeka. In the pre-school period, children are also introduced to basic writing activities. Indicators of beginning writing are, the child can hold a writing instrument well and correctly, is able to move his hand well, the child can imitate letter shapes, the child can recognize letter shapes. Writing test activities in kindergarten are implemented with very simple activities such as bolding letters, making dashes, making shapes and many more. This research was conducted to evaluate written test activities at TKIT Nurussyifa Krebet Jambon Ponorogo. The data sources in this research are the principal, group A teachers, and group A1 students at TKIT Nurussyifa. The method used in this research is a qualitative research method, using a field case study approach. The techniques used in collecting data are observation, interviews and documentation. From the research results, the written test activities carried out at TKIT Nurussyifa have gone well, and are not burdensome for therapy children, showing positive results and are effective in training children's motor skills in beginning writing.

Detection of a low-frequency ion instability in a magnetic nozzle

Abstract A low-frequency ion instability, with frequency f I between the ion gyrofrequency and the lower hybrid frequency f c , i < f I ≪ f LH , is detected in an argon plasma expanding in a magnetic nozzle for magnetic fields between 240 < B z , max < 700 G. The frequency of the instability exhibits a linear dependence with magnetic field strength, and the wave amplitude has a radial maximum that would match the location of a conical density structure, i.e. high-density cones. For all of the magnetic field cases analysed, the high-frequency spectra showed upper and lower sidebands centred around the driving frequency and at a separation equal to the instability frequency, 27.12 MHz ± f I kHz. Measurements of the perpendicular wavenumber would satisfy, for certain magnetic field strengths, the dispersion relation of both an electrostatic ion cyclotron wave (ICW) and of an ion acoustic wave. It is hypothesised that the observed low-frequency wave could be an acoustic-like instability propagating perpendicular to the magnetic field, which develops as an ICW at some magnetic field strengths. From the data collected, it is suggested that the high-frequency sidebands may be caused by modulation of the low-frequency wave.

Feature extraction and pattern recognition in time-lapse pressure transient responses

Monitoring of modern wells equipped with permanent downhole gauges and flowmeters provides large datasets of pressure, temperature and flowrate measurements. On a limited scale, selected events from these datasets are traditionally used in well performance analysis and monitoring, reservoir simulation, and many other tasks employing physics-based models. New methods that combine model- and data-driven approaches for full-scale analysis of these large datasets have recently attracted interest, suggesting new metrics for knowledge extraction. Most recent studies have used a combination of Pressure Transient Analysis (PTA), which is a key reservoir engineering tool, with hybrid methods, such as PTA-metrics and AI-powered models. The emergence of hybrid methodologies combining model- and data-driven approaches has opened new perspectives for comprehensive analysis and knowledge extraction from big well monitoring data sets, accumulated in the industry. Despite their potential, these methodologies often face challenges in reliability, effective data processing, interpretation and feature engineering.This paper introduces a novel PTA-feature extraction and pattern recognition methods for analysis of time-lapse pressure transient responses and their Bourdet derivatives. The pattern recognition method builds on an unsupervised classification method to extract PTA-features, associated with different flow regimes commonly used in PTA. Each pressure transient in a time-lapse series is first processed by an autonomously fine-tuned algorithm that measures the signal's distance to an ensemble of physically meaningful responses defined by PTA-feature library, thus breaking the transient into a series of likely PTA-features. A set of hyperparameters is used in the unsupervised classification, where an optimization procedure is employed for automated tuning of the hyperparameters to a particular transient. Subsequently, recognition of underlying patterns governed by sequences of these PTA-features in the time-lapse transient responses is performed. Testing of the combination of these new methods through synthetic and field cases is further carried out with verification via comparison with expert’ interpretation results. Added value to the previously introduced PTA metrics, which provide on-the-fly well and reservoir performance analysis, is finally demonstrated. The proposed pattern recognition method improves reliability and automates the calculation of the PTA metrics.The developed methodology serves as a new tool for knowledge extraction from big well monitoring datasets, available in the companies operating in the oil and gas industry, as well as the emerging industries such as carbon capture and storage and geothermal energy production. The article concludes with a discussion of the main advantages and limitations of the suggested feature extraction and pattern recognition methods. Besides the combined use of the methods described in this article, these methods may also be integrated with conventional physics-based approaches widely used in the industry for well data interpretation and reservoir simulations, improving their performance and efficiency for big data sets.

Modeling Ion Transport in the Upper Ionosphere of Mars: Exploring the Effect of Crustal Magnetic Fields

AbstractStatistically ion and electron densities are enhanced above strong crustal magnetic field regions according to measurements made by the Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft. Plasma created by ionization of neutrals in the lower ionosphere (where chemistry dominates) flows upward and becomes trapped on closed magnetic field loops. Enhanced ion density in the ionosphere (particularly O2+) is associated with enhanced photochemical escape of atomic oxygen. This paper presents a quasi‐1D multi‐fluid time‐dependent model of the Martian ionosphere for nine ion species. Ionospheric temperatures are adopted but ion densities and velocities (along the field lines) are determined using a numerical solution of the continuity and momentum equations. Diurnal effects are explored by varying photoionization rates. Three crustal field cases are considered: a low altitude closed, a high altitude closed, and a high altitude open field line. Additionally, a case with no crustal field is modeled to provide a comparison between regions with and without crustal fields in the upper Martian ionosphere. Model results show higher ion and electron densities in the crustal field cases than in the purely induced field case. Additionally, we find that densities are generally higher on the closed field lines than on the open field lines, and ion velocities are generally up the field lines, away from the Martian surface. We also find that velocities are larger on the open field line case. We compare modeled density results to MAVEN data and find general agreement. Implications for atmospheric escape, particularly photochemical escape of O, are also discussed.

Effects of fines migration and reservoir heterogeneity on well productivity: analytical model and field cases

Effects of fines migration and reservoir heterogeneity on well productivity: analytical model and field cases

An automatic new approach to gravity anomaly’s profile separation, inversion and interpretation, using an infinite horizontal slab model

ABSTRACT The goal of this research is to develop a new, fast-applying, non-conventional 2D semi-inversion technique that uses data from a previously known control point (e.g. a borehole). The method successfully separated a digitised profile over the Bouguer gravity anomaly map into its components, each of which corresponded to a rock formation being prior chosen from a borehole or control point. The importance of this technique stems from its capacity to automatically analyse the shape of the Bouguer gravity anomaly, as well as its propriety, approximation and given accepted equivalent geological cross-section, utilising an infinite slab model. A preliminary synthetic guidance model (SGM) in this proposed new method is being created from borehole data to simulate the homogeneous density distribution of the rock formations that fill a hypothetical sedimentary basin so that it represents to far extent the history of the region’s sedimentation process. The theoretical gravitational effect for each rock formation is estimated using the infinite horizontal slab model for all rock formations of such a hypothetical basin model. The total of these gravitational effects is utilised to invert any gravity profile that crosses the Bouguer gravity anomaly map. The gravity anomalies of the Bouguer profile are then separated and inverted into the comparable rock formation thicknesses or/and depths tracked along the gravity’s profile using a simple method. The technique was tested on a synthetic model, a synthetic noisy contaminated model, and real data from two different field cases with different geological and lithological characteristics. The first was in the Tucson Basin in Southeast Arizona, USA, and the second on the Mors Salt Dome in North Jutland, Denmark. The method has demonstrated results comparable with prior known information of the borehole existing in the study areas.

Towards modelling AR Sco: generalized particle dynamics and strong radiation-reaction regimes

ABSTRACT Numerical simulations of relativistic plasmas have become more feasible, popular, and crucial for various astrophysical sources with the availability of computational resources. The necessity for high-accuracy particle dynamics is especially highlighted in pulsar modelling due to the extreme associated electromagnetic fields and particle Lorentz factors. Including the radiation-reaction force in the particle dynamics adds even more complexity to the problem, but is crucial for such extreme astrophysical sources. We have also realized the need for such modelling concerning magnetic mirroring and particle injection models proposed for AR Sco, the first white dwarf pulsar. This paper demonstrates the benefits of using higher-order explicit numerical integrators with adaptive time-step methods to solve the full particle dynamics with radiation-reaction forces included. We show that for standard test scenarios, namely various combinations of uniform E- and B-fields and a static dipole B-field, the schemes we use are equivalent to and in extreme field cases outperform standard symplectic integrators in accuracy. We show that the higher-order schemes have massive computational time improvements due to the adaptive time-steps we implement, especially in non-uniform field scenarios and included radiation reaction where the particle gyro-radius rapidly changes. When balancing accuracy and computational time, we identified the adaptive Dormand–Prince eighth-order scheme to be ideal for our use cases. The schemes we use maintain accuracy and stability in describing the particle dynamics and we indicate how a charged particle enters radiation-reaction equilibrium and conforms to the analytical Aristotelian Electrodynamics expectations.

Hodge-to-singular correspondence for reduced curves

We study the summands of the decomposition theorem for the Hitchin system for \operatorname{GL}_{n} , in arbitrary degree, over the locus of reduced spectral curves. A key ingredient is a new correspondence between these summands and the topology of hypertoric quiver varieties. In contrast to the case of meromorphic Higgs fields, the intersection cohomology groups of moduli spaces of regular Higgs bundles depend on the degree. We describe this dependence.

Harnessing Biomimicry for Controlled Adhesion on Material Surfaces.

Nature serves as an abundant wellspring of inspiration for crafting innovative adhesive materials. Extensive research is conducted on various complex forms of biological attachment, such as geckos, tree frogs, octopuses, and mussels. However, significant obstacles still exist in developing adhesive materials that truly replicate the behaviors and functionalities observed in living organisms. Here, an overview of biological organs, structures, and adhesive secretions endowed with adhesion capabilities, delving into the intricate relationship between their morphology and function, and potential for biomimicry are provided. First, the design principles and mechanisms of adhesion behavior and individual organ morphology in nature are summarized from the perspective of structural and size constraints. Subsequently, the value of engineered and bioinspired adhesive materials through selective application cases in practical fields is emphasized. Then, a forward-looking gaze on the conceivable challenges and associated opportunities in harnessing biomimetic strategies and biological materials for advancing adhesive material innovation is highlighted and cast.

Productivity Model Study of Water-Bearing Tight Gas Reservoirs Considering Micro- to Nano-Scale Effects

Tight sandstone is rich in micron- and nano-scale pores, making the two-phase flow of gas and water complex. Establishing reliable relative permeability and productivity models is an urgent issue. In this study, we first used a slip model to correct the gas phase’s no-slip Hagen–Poiseuille equation for nano- and micropores. Then, combined with the fractal theory of porous media and the tortuous capillary bundle model, we established two-phase relative permeability models for nanopores and micropores. These relative permeability models comprehensively consider the gas slippage effect, the initiation pressure gradient, the pores’ fractal characteristics, and water film mechanisms. Based on these models, we developed a three-region coupling productivity model for water-bearing tight gas reservoirs with multi-stage fractured horizontal wells. This productivity model considered the micro- and nano-scale effects and the heterogeneity of fracture networks. Then, the model was solved and validated with a field case. The results indicated that the three-region composite unsteady productivity model for water-bearing tight gas reservoirs, which incorporated micro- and nano-scale effects (with consideration of micro-scale and nano-scale phenomena in the fluid flow), could accurately predict a gas well’s productivity. An analysis of the factors influencing productivity showed that ignoring the micro- and nano-scale effects in water-bearing tight gas reservoirs will underestimate the reservoir’s productivity. The initial water saturation, the two-phase flow’s initiation pressure gradient, and capillary force are all negatively correlated with the productivity of gas wells, while the conductivity of the fractures is positively correlated with gas well productivity.

Analisis Peran Pemerintah dalam Mengupayakan Pencegahan Stunting Untuk Mewujudkan Sumber Daya Manusia yang Berkualitas di Kecamatan Ampek Angkek

Study "Analysis of the Government's Role in Efforts to Prevent Stunting to Create Quality Human Resources in Ampek Angkek District". Theoretically, this study is driven by the quality of human resources, which is quite crucial in determining economic development. Since economic development follows the rise in human resources. By examining the government's involvement in trying to avoid stunting to produce excellent human resources in the Ampek Angkek sub-district which transpires in the past, data from the research field indicates the other direction. This kind of research is field case study research using a descriptive qualitative methodology which analyzes data using interview techniques, documentation and other sources carried out at the sub-district government and numerous cross-sectors in the Ampek Angkek sub-distinct. Based on the findings of the research and data analysis that has been conducted, it can be concluded that there are several shortcomings, mainly: 1. The role of government and cross-sectors has been carried out in accordance with their roles and duties, but there may be shortcomings that have not been optimal, such as uniting cross-sectors that have not been implemented or generating convergence. 2. Insufficient facilities and TPK not proportionate for the size of the region to overcome stunting cases 3. Insufficient information, understanding, or community involvement in helping to avoid stunting.

A New Method for Estimating Oil Well Production Rates Based on Enthalpy Balance Utilizing Temperature Data

Abstract The fundamental objective of this study is to utilize a temperature dataset to achieve accurate rate estimation. This study introduces a graphical method, incorporating suitable assumptions, for predicting flow rates in single-phase vertical oil flow. The method takes into consideration the fouling factor and addresses the steady-state flow of heat in the wellbore, while also accounting for the transient heat conduction in the formation. To evaluate and validate the proposed model, two field cases are examined, and associated uncertainties are discussed. The model's predictions are compared with those obtained from Hassan and Kabir's approach, as well as actual separator flow rate data. The comparisons reveal that the model exhibits a high level of accuracy within its specified range of application. Statistical analyses indicate that most of the models perform comparably, although the suggested graphical model stands out for its higher accuracy and user-friendly nature. The performance of uncertainty is found to be more reliant on the accuracy of data measurement rather than the features of the model itself.

Physical, mechanical, and microstructural characteristics of fly ash replaced cement deep mixing columns

The novel approach of the study is implementing the installation procedure of fly ash (FA) replaced cement deep mixing (DM) columns to field cases aiming at managing FA waste and reducing cement utilization. FA replaced cement DM columns (diameter of 30 cm and length of 80 cm) were installed on clayey soils using a laboratory type DM machine. The effect of installation parameters such as the binder dosage, FA replacement ratio, superplasticizer content, water/binder ratio, and the liquidity index (LI) of the soil on column performance was investigated. The design of experiments and optimization process were conducted using the Taguchi method, S/N and ANOVA analyses, and the desirability function method. Observations have shown that the mixing time required for a homogeneously mixed column depends on the LI of the soil and the volume ratio (VR) of the slurry. A key parameter (LI∙VR) is defined to decide the minimum number of the mixing process. The blade rotation number should be minimum of 252 rev/m to obtain a homogeneous soil-slurry mixture. The highest strength of the column was obtained when LI of fresh soilcrete (LImix) is 1.25∙LI. Optimum installation parameters were determined as binder dosage of 425 kg/m3, FA replacement ratio is 40%, superplasticizer content is 3%, water/binder ratio is 0.8, and LI of the untreated soil is 1. In the optimum design, the mixing efficiency of the soil-slurry mixture increased and the best column performance was obtained. In addition, cement utilization and binder cost decrease 40% and 33%, respectively, in FA-replaced cement DM columns. SEM images prove the increase in column performance due to the cementation products (CSH and CAH gels) formed in the microstructure of the column.

Sanding in Sliding Sleeve Completed Wells Without Sand Control in Moderately Competent Sand-Prone Reservoir Formations: A Field Case

Sanding in Sliding Sleeve Completed Wells Without Sand Control in Moderately Competent Sand-Prone Reservoir Formations: A Field Case

Anisotropy in shale and its impact on AVO modelling and prospect de-risk: a case study of a Central North Sea field

The inherent anisotropy in shale is an attribute associated with its clay minerals platelets alignment and layering and very common with transversely isotropic (TI) medium. This implies that velocity is fastest along the horizontal axis and slowest along the vertical axis, which could affect velocity signature from sonic tools measurements in deviated wells. This may lead to wrong amplitude variation with offset (AVO) signature, inaccurate depth conversions, seismic-to-well tie difficulty etc. Nineteen (19) wells in Forties field andthirteen (13) in Huntington field were investigated and interpreted for the presence of anisotropy effect within the caprock over the reservoir Forties sands of the Sele (shales) Formation. In order to analyse the Thomsen weak anisotropy parameters (ϵ, γ and δ) per field, wells with closer Sele depth range were considered. The well inclinations ( θ ), average compressional (α) and shear (β) velocities per well were utilised for forward and inverse modelling of Thomsen anisotropy equations. The estimated anisotropy (VTI) parameters and the P-wave ( α o ) and S-wave velocities (βo ) at zero inclinations in Sele Formation for the studied wells are: α o = 2448 ± 15.9 m/s, β o = 1003 ± 34.8 m/s, ϵ = 0.15 ± 0.02, γ = 0.33 ± 0.10, δ = 0.030 ± 0.015 in the Forties field Sele, while α o = 2775 ± 23.6 m/s, β o = 1306 ± 47.9 m/s, ϵ = 0.22 ± 0.02, γ = 0.43 ± 0.14, δ = 0.022 ± 0.018 in the Huntington field. AVO responses were compared, assuming both isotropic and anisotropic P–P reflectivity models. Result shows an increase in AVO gradient for all anisotropic case in both fields. AVO signatures were either completely or averagely masked in both fields using the isotropic assumptions. There is also an increase in AVO gradient for all anisotropic cases in both fields. Velocity decreases of about 1.2% and 3.5% were observed in the Sele Formation for the Forties and Huntington fields respectively for anisotropy. The corrected two-way traveltime (TWT) should in principle allow for a better seismic-to-well tie estimation. Similarly, using the faster deviated velocity (i.e. uncorrected velocity) in any depth conversion would result in under estimation of the actual depth across the field.

Integrated Simulation for Microseismic Fracture Networks with Automatic History Matching in Tight Oil Development: A Field Case from Block Y2 in Ordos Basin, China

Integrated Simulation for Microseismic Fracture Networks with Automatic History Matching in Tight Oil Development: A Field Case from Block Y2 in Ordos Basin, China

A semi-analytical fracture high-conductivity location diagnostic method for vertically fractured wells in multilayered reservoirs: field case study

Deep multilayered reservoirs are usually developed using multilayered fracturing techniques; however, the non-uniform placement of proppant causes uneven distribution of fracture conductivity. This study introduces a semi-analytical well test model for hydraulically fractured wells in multilayered reservoirs, accounting for varying fracture conductivity within the hydraulic fracture. The model is built upon the point source function, boundary element method, Duhamel theorem, and pressure superposition principle. Verification tests are conducted to ensure calculation accuracy. Sensitivity analysis is performed on key parameters, encompassing the transmissibility factor, storativity factor, fracture extension, and fracture conductivity. The findings indicate that 1) Increased heterogeneity among layers correlates with a more pronounced pressure drop; 2) Poorly-propped fracture conductivity influences the duration of bilinear flow, becoming negligible after linear flow; 3) The model’s applicability extends to other multilayered reservoirs (e.g., carbonate reservoirs) with minor adjustments. Lastly, a case study from Xinjiang oilfield is presented to demonstrate that the proposed method can derive reservoir and fracture properties for each layer individually. This study contributes to a deeper understanding of the potential of pressure data in characterizing multilayered reservoirs.

Time‐frequency domain correlation method based on the synchrosqueezed wavelet transform for tunnel vibroseis and its application

AbstractTo meet the demand for long‐distance and highly accurate detection in tunnel construction, a vibroseis source has been introduced into tunnel forward prospecting. However, serious noise in tunnels reduces the resolution of vibroseis signals, and small‐scale structure recognition in tunnels requires higher signal resolution. Thus, we develop a time‐frequency domain correlation method based on the synchrosqueezed wavelet transform for tunnel vibroseis data. Time‐frequency domain correlation may capture more information than a single time or frequency domain correlation method, and its effectiveness depends on the time‐frequency transformation method. The synchrosqueezed wavelet transform allows us to obtain high‐resolution time‐frequency spectra and thus helps to extract high‐resolution effective signals. The advantages and disadvantages of different correlation methods are highlighted using numerical examples, in which the high resolution and strong robustness of the time‐frequency domain correlation method based on the synchrosqueezed wavelet transform are demonstrated. A detailed field case study in an iron mine tunnel further demonstrates the reliability of the time‐frequency domain correlation method based on the synchrosqueezed wavelet transform for practical data.