Summary This research adapts the ground reaction curve (GRC) method, traditionally used in tunnel engineering, to analyze wellbore stability and determine the optimal drilling fluid weight in oil and gas operations. The objectives are to assess wellbore stability under varying conditions and establish a safe drilling fluid pressure window. The methodology employs analytical solutions based on the Mohr-Coulomb failure criterion and numerical modeling using FLAC software. Results demonstrate that parameters such as pore pressure, in-situ stress ratios, and wellbore radius influence wellbore convergence, with the numerical GRC method providing a larger safe drilling fluid pressure window compared to the analytical approach, potentially enhancing drilling efficiency and reducing operational risks. Introduction Wellbore stability is increasingly critical in the oil and gas industry as drilling operations target complex geological formations to meet rising energy demands. Conventional analytical methods for determining safe drilling fluid weights often rely on simplifying assumptions that may not fully address the challenges posed by these environments. This study introduces a novel approach by adapting the ground reaction curve (GRC), a concept from tunnel engineering, to wellbore stability analysis. The GRC relates internal pressure to radial displacement, offering a framework to evaluate rock mass behavior under varying conditions. Pertinent literature highlights diverse approaches to wellbore stability, including elastoplastic and poroelastic models, and failure criteria such as Mohr-Coulomb, Mogi-Coulomb, and Hoek-Brown [1-2]. Building on these foundations, this research employs two methods: an analytical approach using the Mohr-Coulomb criterion with Kirsch equations to calculate stress distributions and critical pressures, and a numerical approach using FLAC software to simulate wellbore excavation and generate the GRC. The study investigates the effects of pore pressure, stress anisotropy, and wellbore radius on stability. The main findings indicate that the numerical method yields a broader safe drilling fluid pressure window, offering potential operational advantages over the analytical method. Methodology and Approaches The methodology integrates analytical and numerical techniques to assess wellbore stability. Analytically, stress distributions around the wellbore are computed using the Kirsch equations, which describe radial and tangential stresses as functions of drilling fluid pressure, in-situ stresses, and Poisson’s ratio. The Mohr-Coulomb failure criterion is then applied to determine the minimum pressure preventing shear failure (collapse) and the maximum pressure avoiding tensile failure (fracturing), establishing the safe pressure window. Numerically, the FLAC software (version 8) simulates wellbore excavation in a two-dimensional model under hydrostatic and anisotropic stress fields. The GRC is generated by monitoring radial displacement as internal pressure varies. The lower limit of the safe pressure window is identified when the wellbore stabilizes (e.g., at 75% of in-situ stress in the hydrostatic case), while the upper limit is determined by minimizing the plastic zone around the wellbore (e.g., at 42 MPa). The study also examines the sensitivity of the GRC to pore pressure, stress ratios, and wellbore radius, with parameters detailed in the original paper’s Table 1. This dual approach provides a comprehensive stability analysis, with sufficient detail to replicate the methods or refer to cited works [3-4]. Results and Conclusions The GRC analysis shows that increased pore pressure, stress anisotropy, and wellbore radius amplify convergence. Table 1 compares the safe drilling fluid pressure windows from both methods in a hydrostatic field (σH = σh = 30 MPa). The numerical GRC method consistently provides a larger window across conditions, enhancing drilling flexibility. Fig. 1 visually contrasts these windows, confirming that the numerical GRC method generally provides a larger safe range across conditions, enhancing drilling flexibility. This principle suggests that integrating displacement-based numerical analysis with failure-based analytical methods improves stability assessment. An exception occurs in specific hydrostatic cases where the numerical window narrows slightly, possibly due to differing criteria emphasis. Theoretically, this approach refines wellbore mechanics understanding; practically, it suggests cost and risk reductions. Validation with field data remains necessary. The study concludes that the GRC method is a promising tool for optimizing drilling fluid design, recommending further testing across diverse formations.

Setback structures are highly vulnerable during earthquakes due to its vertical geometrical and mass irregularity, but the vulnerability becomes higher if the structures also have stiffness irregularity in elevation. The risk factor of such structure may increase, if the structure rests on sloping ground. In this paper, an attempt has been made to evaluate the seismic performance of setback structures resting on plain ground as well as in the slope of a hill, with soft storey configuration. The analysis has been performed in three individual methods, equivalent static force method, response spectrum method and time history method and extreme responses have been recorded for open ground storeyed setback building. To mitigate this soft storey effect and the extreme responses, three individual mitigation techniques have been adopted and the best solution among these three techniques is presented.

The aim of this study is to create a Mercalli intensity map and evaluate the ground failure probability caused by liquefaction in the Bogura district. To generate a Mercalli intensity seismic microzonation map, first the shear wave velocity (Vs) was determined by analyzing data from 345 soil test reports. The conversion of Vs to site amplification factor (AF) and Peak Ground Acceleration (PGA) was carried out using the widely used empirical equations, considering earthquake magnitudes 1850–2023. Finally, the susceptibility of liquefaction was evaluated for the study area using 345 borehole data, considering a probable earthquake magnitude and site-specific PGA. Some of the frequently used empirical methods are utilized for the evaluation, and the results are presented in the form of hazard maps indicating factors of safety, liquefaction potential, and ground failure probability. The results demonstrate that the least and maximum PGA are both 0.06 g and 0.16 g, while the AF ranges from 1.903 to 3.98 between the minimum and maximum. Moreover, the surface acceleration (SA) varies between 0.143 g and 0.51 g. Based on the Mercalli Intensity seismic microzonation map, 22.45% of the areas have intensity VII, 72.9% of the regions have intensity VIII, and 4.65% of the areas have intensity IX. The hazard map reveals that 2% of the study region is judged to be at extremely high risk for ground failure due to liquefaction during the scenario earthquake. Additionally, it was determined that 13% and 44% of the study region's regions were at high or moderate risk of ground failure under the aforementioned earthquake scenario. The intensity and hazard maps created for Bogura district are crucial to achieving sustainable development goals.

Wheat ground beetle Zabrus tenebrioides (Goeze) (Coleoptera: Carabidae) is an important wheat pest in Iran and some regions of the world. This pest causes damage to wheat by feeding on the root, stalk, and leaves. Farmers try to control this pest by the foliar application of different insecticides, but this method causes damage to the environment. To find an effective method to control this pest, the thiamethoxam insecticide (Cruiser®) efficiency was evaluated using seed treatment in this study. An experiment based on a randomized complete block design with four treatments and four replications was conducted in a field in Ramhormoz city, Khuzestan province (Iran). The treatments were 150 and 200 ml of thiamethoxam plus 2350 ml of water for seed treatment, 2,000 ppm of diazinon by field spraying at the wheat tillering stage, and a control. The results indicated that the average plant density in 150 and 200 ml of thiamethoxam (333.58 and 333.28 plant/m2, respectively) was more than those of diazinon (258.28 plant/m2) and the control (182.12 plant/m2). The average ear density in 150 and 200 ml of thiamethoxam (513.78 and 506.12 plant/m2, respectively) was more than those of diazinon (321.22 plant/m2) and the control (260.86 plant/m2). According to the present results, farmers can use 150 ml of thiamethoxam plus 2350 ml of water for 100 kg of seeds to control this pest by seed treatment.