IntroductionThe "novel weapon hypothesis" posits that invasive plants suppress native species by releasing allelochemicals, which is a crucial factor for their successful invasion. While most studies focus on interspecific allelopathy, with insufficient attention paid to intraspecific allelopathy.MethodsThis study employed an in pot experiment with different litter concentrations (0, 5, 10, 20 g/kg) to cultivate Solanum rostratum Dunal seedlings in both sterilized and unsterilized soils. The plant growth parameters, soil physicochemical properties, soil metabolites, and soil microbial communities were measured, and their interrelationships were also analyzed.ResultsThe results indicated that the litter from Solanum rostratum Dunal significantly inhibited the growth of its seedlings, and the inhibitory effect is even stronger in sterile soil. Additionally, the addition of litter decreased the soil pH value, while increasing the soil electrical conductivity, total carbon, total nitrogen and total phosphorus contents. Metabolomic analysis identified the phenolic compound 4-Ethyl-2-methylphenol and the ester compound Carvyl propionate as main secondary metabolites in soil, whose concentrations showed significant negative correlations with seedling growth. In unsterilized soil, the abundance of Sphingomonas and Dongia—bacteria with degradation potential—increased, exhibiting negative correlations with allelopathic metabolite levels and positive correlations with seedling growth indicators.DiscussionIn summary, the self toxic effect of Solanum rostratum Dunal litter on seedling growth increased with the increasing of litter content, and soil microorganisms mitigate the allelopathic effects by degrading or transforming allelopathic compounds in litter, thereby playing a crucial role in regulating its invasion process.
Abstract Deepwater drilling in offshore Indonesia, is fraught with technical hurdles especially in the soft sandstone formations, where Wellbore instability, compromised formation integrity, and inefficient solids transport routinely threaten project success. These risks are further amplified in high-angle Wells. Under such conditions, effective hole cleaning and the removal of mud cake and cuttings become critical concerns. In previous sidetrack attempts (well AA-ST01 and well AA ST-02), these challenges resulted in substantial Non-Productive Time (NPT) due to borehole instability, lost circulation, and stuck pipe incidents. To mitigate these challenges, a continuous circulation system (CCS) was implemented in Sidetrack 3 (well AA ST-03), targeting 4,550m MD/2,721m TVD, and 75° inclination. This paper evaluates the effectiveness of a continuous circulation system in addressing Extended Reach Drilling (ERD)-related challenges and improving overall drilling efficiency and reliability. By equipping every stand of drill pipe with continuous circulation system subs, the operation achieved uninterrupted bottomhole pressure (BHP) and constant fluid circulation during pipe connections and static events. This approach minimized the additional circulating time required for hole cleaning after drilling sequence. The integration of continuous circulation system was specifically intended to enhance hole cleaning efficiency and solids transport and mitigating formation integrity risks, such as pack-off leading to stuck pipe incidents that had been major contributors to non-productive time in previous operations. The results shown successful drilling of well AA ST-03 with full application of continuous circulation system that effectively addressed the major challenges encountered in previous sidetracks. A total of 1,665 m was drilled across two sections (8-1/2″ × 10-1/4″ and 8-1/2″), marking the deepest ERD Well in Indonesia, accomplished with the deployment of 30 continuous circulation system subs. Continuous circulation was successfully maintained throughout drill pipe connections for 7 days without interruption. The technology significantly reduced NPT maintained Wellbore stability, and improved cuttings transport performance. This success highlights the transformative potential of continuous circulation system in revolutionizing the longest and complex ERD deepwater Well in Indonesia. This case provides new insight into the practical application of continuous circulation system in one of the most technically challenging deepwater ERD Wells in Indonesia. The study demonstrates reduced NPT, maintains wellbore stability as evidenced by no pipe stuck events in this drilling section, and improved the hole cleaning. These outcomes recommend continuous circulation system as a best-practice solution for enhancing efficiency and reliability in extended-reach and high-angle drilling projects in Indonesia's offshore reservoirs and other similarly challenging environments worldwide.
Abstract A mature tight gas-condensate field, producing since 2023, features two hydraulically fractured sandstone reservoirs commingled through a legacy limited-entry completion designed for water avoidance and fracture-height control. While effective in early field life, this completion geometry has constrained pressure communication, leading to elevated near-wellbore velocities, accelerated decline rates, and instability in certain wells. Under a Wells, Reservoir, and Facility Management (WRFM) initiative integrated with Completion & Well Intervention (CWI) practices, a comprehensive re-evaluation of perforation strategy was undertaken to alleviate near-wellbore restrictions, improve drawdown balance between commingled stacks, and safely access depleted tight zones where conventional slim-gun deployment was not viable. The approach introduced an integrated WRFM–CWI workflow that combines reservoir diagnostics, simulation, and perforation redesign to identify optimal target intervals overlooked during the initial limited-entry completion. Key innovations include pre-job equilibrium and drawdown modeling, strategically placed relief perforations to moderate inflow, modified gun selection and tension-management techniques, and real-time surface monitoring to mitigate operational risks. This methodology was applied across multiple wells. Observed outcomes include initial gas-condensate production increase by 10% - 15%, reduced solids production issues from some wells, successful deployment of standard guns in depleted zones, and enhanced operational understanding for sequencing and zonal selection. Post-intervention logging and production data confirmed contributions from previously underutilized intervals, while operational learnings enabled workflow optimization for subsequent wells. This study demonstrates a practical, replicable workflow for tight gas-condensate reservoirs, expanding the safe operating envelope for re-perforating depleted intervals and providing a tested pathway to optimize recovery beyond legacy limited-entry completions. The WRFM–CWI integration highlights the value of combining reservoir management with well intervention practices to unlock measurable production improvements in mature fractured reservoirs, offering broader applicability for similar fields worldwide.
Abstract Recently, there has been a growing focus on understanding material behaviors to improve product designs in the oil and gas (O&G) industry. This paper aims to apply fracture mechanics principles to predict the stress and strain state of rubber when feeding lines through splice-less swellable packers. Specifically, various rubber elastomer shapes are examined through Finite Element Analysis (FEA) in ABAQUS/Explicit, guided by experimental data. The fracture damage mechanism of rubber is more complex compared to metallic parts, and it is crucial for ensuring product reliability. In cased or open-hole environments, swellable systems with cable feedthroughs are utilized to achieve zonal isolation of producing zones during downhole operations. A dedicated tool has been developed to facilitate cable installation during the feedthrough process. To have a better understanding of hyper-elastic behavior in rubbers at large deformations and identify optimal geometrical designs, FEA is conducted in ABAQUS/Explicit, coupled with a user subroutine (VUSDFLD). Test results are used to calibrate the material properties, enabling a comprehensive representation of the material behavior under damage conditions. The experimental model is replicated by a finite element model based on the comparison of measured and calculated forces acting onto the rubbers. Similar deformation patterns are observed. In the numerical model, the initial development is based on maximum principal strain-based crack initiation, with element removal utilized to approximate the damage initiation and evolution. With such a calibrated numerical model, four different geometries are examined: circular, square, trapezoidal, and winged shapes. The optimal design is determined based on achieving the lowest load to stroke the same displacement while minimizing the volume of rubber with higher strain state. It's found that the optimal shape is the winged shape, significantly reducing peak principal strain around the hole boundary compared to typical circular profiles. In summary, fracture mechanics principles are studied and applied in the numerical analysis to predict the stress and strain states of rubbers and provide guidelines in the tool designs in cable feedthrough installations. This approach ensures enhanced reliability of cable systems, crucial for risk reduction during completion system installations.
