During the oil shale drilling in Group Q of Block GL, the shale is prone to hydration, deterioration, sidewall exfoliation and frequent collapse, which affects the efficient exploration and development of shale oil. In order to reveal the mechanism o...
To overcome wellbore instability problems in deep coalbed gas reservoirs in the Ordos Basin, drilling fluid additives were evaluated and a drilling fluid system was designed. According to the SEM and CT analysis results, there were not only face and...
The article presents the recipe for ultra-lightweight cement slurry for wellbore sealing. In ordinary lightweight cement slurries, the addition of microspheres and a large amount of water are used to maintain rheological parameters. This is a problem...
The study of wellbore stability in offshore gas hydrate reservoirs is an important basis for the large-scale exploitation of natural gas hydrate resources. The wellbore stability analysis model in this study considers the evolution of the reservoir m...
Most studies related to aspects of wellbore stability, such as wellbore breakage, block dropping, and wellbore expansion, revolve around the physicochemical interaction between drilling fluid and surrounding rock, but relevant studies show that drill...
With the development of coal resource extraction and wellbore construction proceeding towards deeper depths, the stability of drilling wellbore structures has become increasingly severe, even posing a barrier to the use of drilling method technology...
Gas hydrates have great potential as future energy resources. Several productivity and stability analyses have been conducted for the Ulleung Basin, and the depressurization method is being considered for production. Under depressurization, ground se...
The stability of hydrate-bearing near-wellbore reservoirs is one of the key issues in gas hydrate exploitation. In most previous investigations, the damage evolution process of the sediment structure and its effect on near-wellbore reservoir stabilit...
The use of multilateral wells is an important method to effectively develop complex oil reservoirs, and wellbore stability research of multilateral wells is of great importance. In the present study, the effects of formation fluids and rock damage we...
Wellbores drilled in igneous formation with weak interlayers face significant risk of instabilities. This study aims to investigate the underlying mechanisms of these instabilities by employing a combination of rock mechanics tests and numerical simu...
The stability of the oil well wellbore is a prerequisite for selecting the optimal completion method. In this paper, based on experimental testing and theoretical models of rock mechanics parameters in deep oil reservoirs, the in situ stress paramete...
The issue of wellbore instability poses a significant challenge in the current exploration of shale gas reservoirs. Exploring more efficient shale stabilizers has always been a common goal pursued by researchers. In this paper, a novel shale stabiliz...
Wellbore instability remains a critical challenge over the entire service life of oil and gas wells, especially in deep carbonate reservoirs. This study integrates triaxial rock mechanics experiments and acoustic emission (AE) Kaiser effect tests to...
The South China Sea has abundant reserves of natural gas hydrates, and if developed effectively, it can greatly alleviate the pressure on the energy supply in China. But the hydrate reservoirs in the sea area are loose, shallow, porous, and have poor...
The borehole wall stability of depleted reservoirs is a key problem that restricts the deeper potential exploitation of old oilfields. Based on these, according to the seepage and elastic mechanics theory of porous media, combined with laboratory roc...
The past decade has seen increased focus on nanoparticle (NP) based drilling fluid to promote wellbore stability in shales. With the plugging of NP into shale pores, the fluid pressure transmission can be retarded and wellbore stability can be improv...
Marine gas hydrate formations are characterized by considerable water depth, shallow subsea burial, loose strata, and low formation temperatures. Drilling in such formations is highly susceptible to hydrate dissociation, leading to gas invasion, well...
In order to prevent and control the problem of wellbore instability during the drilling process in shale formations, this study, based on the unique rheological properties, water solubility, and thermal stability of sodium alginate (SA), systematical...
The development of cracks and solution cavities in carbonate reservoirs can notably reduce the rock’s mechanical properties, leading to a severe wellbore collapse problem during drilling operations. To clarify the influence of the characteristi...
Deep drilling can lead to the encounter of complex geological conditions, with significant overburden pressure leading to a narrow safety window for mud density. In this study, we deviated wellbore instability conditions using the Mohr–Coulomb...
During drilling operations, drilling fluids undergo heat exchange with hydrate-bearing formations. The intrusion of drilling fluids affects hydrate stability, leading to variations in stress fields around a wellbore and complex scenarios such as bore...
This research explores the geomechanical challenges associated with gas hydrate extraction in submarine slope zones, a setting posing a high risk of significant geological calamities. We investigate slope and wellbore deformations driven by hydrate d...
Wellbore stability is one of the major challenges during drilling operations in shale gas formations. Drilling fluid seepage can significantly alter the pore pressure around the wellbore, thereby inducing wellbore instability. In this study, the Darc...
Wellbore instability is a major constraint in large-scale shale oil extraction. This study focuses on the shale–sandstone interbedded shale oil reservoirs in the Chang 7 area, delving into the evolutionary principles governing wellbore stabilit...
Wellbore stability is a crucial factor affecting the safe exploitation of offshore natural gas hydrates. As a sustainable energy source, natural gas hydrate has significant reserves, high energy density, and low environmental impact, making it an imp...
Serious borehole instability problems are often related to the presence of weakness planes in rock formations. In this study, we investigated the stability of wellbores drilled along a principal direction and parallel to the weakness planes. We used...
The main objective of this research work was the wellbore stability evaluation of oil and gas wells based on a 3D geomechanical model, which as constructed using seismic inversion in a southeastern Algerian petroleum field. The seismic inversion mode...
Wellbore instability, particularly in shale formations, presents a great challenge to modern drilling operations. Although conventional chemical inhibitors are frequently employed in water-based drilling fluids, they may not always function in highly...
Currently, coal borehole collapses frequently occur during drilling. Considering that the coal near to the wellbore is cut into blocks, and the cleat filler of the coal influences the stress distribution near the wellbore, a new theoretical solution...
Most old oil and gas fields worldwide are depleted, making drilling in these sedimentary zones extremely difficult, especially in complex pore pressure regimes when they are accompanied by over-pressure zones. Considering that typical wellbore stabil...
Shale hydration dispersion and swelling are primary causes of wellbore instability in oil and gas reservoir exploration. In this study, inulin, a fructo-oligosaccharide extracted from Jerusalem artichoke roots, was modified by acylation with three ac...
The problem of wellbore stability has a marked impact on oil and gas exploration and development in the process of drilling. Marine mussel proteins can adhere and encapsulate firmly on deep-water rocks, providing inspiration for solving borehole stab...
This study presents a new interface for wellbore stability analysis, which visualizes and quantifies the stress condition around a wellbore at shear and tensile failure. In the first part of this study, the Mohr–Coulomb, Mogi–Coulomb, mod...
This study employs a finite element approach to investigate wellbore stability in interbedded weak formations, such as unconsolidated layers, with a focus on the failure-tendency method, which is derived according to the principle of Mohr–Coulo...
The safe exploitation of marine natural gas hydrates, a promising cleaner energy resource, is hindered by reservoir instability during drilling. The inherent temperature–pressure sensitivity and cementation of hydrate-bearing sediments leads to...
The abnormal pore pressures in ultra-deep wells in the Junggar Basin, China are constantly causing drilling incidents for both the drilling engineers and geologists. Formation pore-pressure is an important parameter in wellbore stability analysis, an...
This study investigates wellbore stability in ultra-deep extended-reach wells (ERWs) in the East China Sea, where perforated pipes (a type of screen completion) are commonly used to support wellbore walls and prevent collapse. Cost constraints someti...
The economic viability of geothermal energy depends on wells that can be constructed and operated reliably. Wellbore instability can delay drilling, require remediation, and interrupt operation. Stability modelling supports risk reduction when its me...
Wellbore instability in clay-rich intervals remains a major drilling challenge, even when the selected fluid density satisfies the conventional pressure window. This study evaluates delayed instability during exposure to a low-salinity water-based dr...
The X-ray computed tomography method has provided unrivalled data about the characterization and evolution of the internal/external structure of materials by analyzing CTN and non-destructive imaging approach. Applying this method on the appropriate...
Co-exploitation of coal measure gases (coalbed gas, shale gas, and tight sandstone gas) puts a higher requirement on drilling fluids. Conventional drilling fluids have disadvantages, such as causing problems of borehole collapse, formation damage, an...
Coal is inherently soft, characterized by well-developed cleat systems, low strength, and significant anisotropy. Existing models that treat coal as a continuous medium or consider only a single plane of weakness fail to capture the synergistic effec...
Accurate characterization of heat transfer in a wellbore during drilling, which includes fluid circulation, is important for wellbore stability analysis. In this work, a pseudo-3D model is developed to simultaneously calculate the heat exchange betwe...
Gas hydrate-bearing formations are characterized by low temperature and high pressure, weak cementation, strong phase sensitivity, and pronounced heterogeneity. During drilling in such formations, the drilling fluid is required to maintain wellbore s...
Based on the whole life cycle process of the economic exploitation of natural gas hydrate, this paper proposes the basic problem of stabilizing the wellbore for the basic conditions that must be met to ensure the integrity of the wellbore for exploit...
Given the great burial depth, ancient depositional age, and multi-phase tectonic evolution of deep formations, drilling operations are highly susceptible to wellbore instability. The design and deployment of directional wells further exacerbate this...
The instability of wellbore in hard and brittle shale formations is a key bottleneck constraining the safety and efficiency of drilling engineering. Traditional studies focused on drilling fluid density, particle plugging, and chemical inhibition; ho...
Significant stress changes caused by sorption-induced swelling raise the coal wellbore failure potential, which directly impacts the safety and sustainability of CO2 enhanced coalbed methane (CO2-ECBM). Additionally, a mixture gas (CO2/N2) injection...
Due to the uncertainty of formation properties and improper wellbore stability analysis methods, the input parameters are often uncertain and the required mud weight to prevent wellbore collapse is too large, which might cause an incorrect result. Ho...
Multilateral wells can effectively develop complex reservoirs at a lower cost, which, in turn, enhances the overall efficiency of oilfield exploitation. However, drilling branch wells from the main wellbore can disrupt the surrounding formation stres...
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