Study and Comparison of Swelling and Compressibility Characteristics of Crumb Marl, Flaky Marl with Attapulgite and Sandy Clay from the Diamniadio Urban Pole at the Oedometer

In Senegal, the Diamniadio, Sebikhotane and Bargny sector contains clay soils that are problematic for construction. In order to have more information on the behavior of the clay soils of Diamniadio, free swelling tests followed by load-discharge cycles were carried out according to standard NF P 94-090-1. These tests were carried out using an Oedometric device on the three samples from the study site (sandy clays with calcareous concretion, marls with crumbs and laminated marls with attapulgite) to apprehend their swelling aspects in saturated conditions. For the free swelling test, a determination of the different swelling phases will be carried out followed by a comparison of the rate of evolution of the phases for the three samples from the site. In the same vein, the compressibility characteristics of the samples will also be provided from load-unload Oedometric tests. Thereafter, we proceed to a comparison of the void index at the initial state of the samples after two charge-discharge cycles and the influence of the cycles on the reorganization of the internal structure of the samples. These studies will provide more information on the swelling behavior of Diamniadio soils in the presence of water.

A laboratory study of a novel bio-based nonionic surfactant to mitigate clay swelling

This study reports the applicability of quillaja saponin(QS)as a vigorous and environmentally friendly shale swelling inhibitor.QS is a natural surfactant,which is extracted from herbal sources.The inhibition strength of this surfactant was assessed through various experiments,such as sedimentation,inhibition,filtration,particle size,Scanning Electron Microscope(SEM)images,and cutting recovery.Data obtained from these tests illustrated that QS greatly inhibits clays from swelling.The optimal concentration for QS in this intend was 10 g/L.Compatibility of this surfactant with other common additives was also investigated,which showed that it is totally compatible.Finally,the potential inhibition mechanism was assessed through thermal gravimetric analysis(TGA),zeta potential,and contact angle measurement experiments.Surface coating,and wettability alteration of clay particles to the oil-wet state was recognized as the most probable mechanism.

Synthetic polymers:A review of applications in drilling fluids

With the growth of deep drilling and the complexity of the well profile,the requirements for a more complete and efficient exploitation of productive formations increase,which increases the risk of various complications.Currently,reagents based on modified natural polymers(which are naturally occurring compounds)and synthetic polymers(SPs)which are polymeric compounds created industrially,are widely used to prevent emerging complications in the drilling process.However,compared to modified natural polymers,SPs form a family of high-molecular-weight compounds that are fully synthesized by undergoing chemical polymerization reactions.SPs provide substantial flexibility in their design.Moreover,their size and chemical composition can be adjusted to provide properties for nearly all the functional objectives of drilling fluids.They can be classified based on chemical ingredients,type of reaction,and their responses to heating.However,some of SPs,due to their structural characteristics,have a high cost,a poor temperature and salt resistance in drilling fluids,and degradation begins when the temperature reaches 130℃.These drawbacks prevent SP use in some medium and deep wells.Thus,this review addresses the historical development,the characteristics,manufacturing methods,classification,and the applications of SPs in drilling fluids.The contributions of SPs as additives to drilling fluids to enhance rheology,filtrate generation,carrying of cuttings,fluid lubricity,and clay/shale stability are explained in detail.The mechanisms,impacts,and advances achieved when SPs are added to drilling fluids are also described.The typical challenges encountered by SPs when deployed in drilling fluids and their advantages and drawbacks are also discussed.Economic issues also impact the applications of SPs in drilling fluids.Consequently,the cost of the most relevant SPs,and the monomers used in their synthesis,are assessed.Environmental impacts of SPs when deployed in drilling fluids,and their manufacturing processes are identified,together with advances in SP-treatment methods aimed at reducing those impacts.Recommendations for required future research addressing SP property and performance gaps are provided.

Stabilization of Clay Soil for the Durability of Structures: Case Study of the Soils of the Locality of Zalimé, Commune of Zogbodomey in the Republic of Benin

Structures erected on swelling clay soils are subjected to several stresses which are at the origin of the premature deterioration of the infrastructures. The soils being supports for the works, the improvement of their weak characteristics with cotton fibers will not only increase the bearing capacities of these soils and the resolution of the environmental problem, by eliminating the CO2 produced by the burning of the stems after harvest. The objective of this study is to contribute to the improvement of the characteristics by cotton stalk powder of the swelling clay soils used as the foundation of the infrastructures in order to guarantee their durability. Identification and mechanical parameterization tests were carried out on raw soil samples taken at 1.5 meters deep and on samples improved with cotton stalk powder at different levels (3%, 6% and 10%). The results from the physical tests reveal that the soil studied is very plastic silt. As for the mechanical tests, it appears that by adding 3% cotton stalk powder to dry density which goes from 1.435 t/m3 compared to the control sample with a dry density of 1.50 t/m3;which reflects an improvement in the compaction characteristics of the soil studied. The dry densities are 1.445 t/m3 and 1.29 t/m3 for the samples improved with 6% and 10% cotton stalk powder.

Clays in radioactive waste disposal

Clays and argillites are considered in some countries as possible host rocks for nuclear waste disposal at great depth.The use of compacted swelling clays as engineered barriers is also considered within the framework of the multi-barrier concept.In relation to these concepts,various research programs have been conducted to assess the thermo-hydro-mechanical properties of radioactive waste disposal at great depth.After introducing the concepts of waste isolation developed in Belgium,France and Switzerland,the paper describes the retention and transfer properties of engineered barriers made up of compacted swelling clays in relation to microstructure features.Some features of the thermo-mechanical behaviors of three possible geological barriers,namely Boom clay（Belgium）,Callovo-Oxfordian clay（France） and Opalinus clay（Switzerland）,are then described,including the retention and transfer properties,volume change behavior,shear strength and thermal aspects.

Empirical study of magnetohydrodynamic effect on fluid flow in clayey porous media

Enhancing oil recovery from clayey reservoirs is a significant challenge in petroleum industry due to complex interactions between fluids and rock surfaces,particularly clay swelling.This study presents the first empirical analysis of magnetic fields'impact on fluid flow in clayey porous media.Our core findings indicate that magnetic treatment of water increases oil recovery by an average of 15–30%in clayey media,with limited effectiveness in pure quartz media.Detailed experiments unraveled that improved recovery factor by magnetic treatment stem from both mitigated swelling and altered magnetic properties at clay surface;introducing 30%clay to porous medium decreased the recovery by 32%compared to pure quartz sand.Heating the clay to around 1000°C to reduce its swelling property improved the recovery by only 16%,suggesting magnetic treatment is not solely attributed to clay swelling mitigation.Treating ferromagnetic films at clay surface with HCl to produce non-magnetic FeCl_(3) resulted in a high recovery factor,similar to the clay-free medium.Moreover,it was determined that a magnetic field intensity of 43760–51740 A/m is optimal for fluid displacement in clayey media.Notably,the intensity of 47760 A/m increased recovery to 84.5%in a 30%clay medium,compared to 49.7%without treatment.Interestingly,it was observed that the maximum flow rate was associated with zero potential difference across the medium,providing a faster method to determine the optimum magnetic field intensity.Lastly,the concept of‘Magnetic memory’was investigated,referring to the persistence of magnetic field's influence after its removal.Our findings indicated that pressure build-up time stability lasted 10 days post-treatment,after which water behavior reverts,and clay swelling resumes.This insight into the temporal dynamics of magnetic field application provides a deeper understanding of its long-term impacts on fluid flow in clayey reservoirs.

Swelling of clay minerals in ammonium leaching of weathered crust elution-deposited rare earth ores

The effect of hydrated radius, cation valence, pH and solution concentration on the zeta potential of clay minerals was investigated, and the relation between zeta potential of clay minerals and swelling was discussed in different leaching agents as well. The results show that the zeta potential of clay minerals decreases with the hydrated ionic radius increasing. It could be seen that the zeta potential of the clay minerals in AICl3 solution is positive,whereas that in NH4C1, KCl and MgCl2 solution is negative. And the zeta potential of clay minerals increases with the cation valence increasing. Moreover, the zeta potential of clay minerals decreases with the solution pH increasing,whereas that increases with the solution concentration increasing in different ammonium solutions. In addition,the swelling of clay minerals decreases while the zeta potential of clay minerals increasing in different ammonium solutions. The ability of compound ammonium to inhibit the swelling of clay minerals is lower than that of single ammonium solution.

Behavior and characteristics of compacted expansive unsaturated bentonite-sand mixture

Limited studies dealt with the expansive unsaturated soils in the case of large-scale model close to the field conditions and therefore, there is much more room for improvement. In this study, expansive （bentonite–sand （B–S） mixture） and non-expansive （kaolin） soils were tested in different water contents and dry unit weights chosen from the compaction curve to examine the effect of water content change on soil properties （swelling pressure, expansion indices, shear strength （soil cohesion） and soil suction） for the small soil samples. Large-scale model was also used to show the effect of water content change on different relations （swelling and suction with elapsed time）. The study reveals that the initial soil conditions （water content and dry unit weight） affect the soil cohesion, suction and swelling, where all these parameters slightly decrease with the increase in soil water content especially on the wet side of optimum water content. The settlement of each soil at failure increases with the increase in soil degrees of saturation since the matric suction reduces the soil ability to deform. The settlement observed in B–S mixture is higher than that in kaolin due to the effect of higher swelling observed in B–S mixture and the huge amount of water absorbed which transformed the soil to highly compressible soil. The matric suction seems to decrease with elapsed time from top to bottom of tensiometers due to the effect of water flowing from top of the specimen. The tensiometer reading at first of the saturation process is lower than that at later period of saturation （for soil sample B–S3, the tensiometer #1 took 3 d to drop from 93 kPa to 80 kPa at early stage, while the same tensiometer took 2 d to drop from 60 kPa to 20 kPa）.

Relationship between Landslides, Geologic Structures, and Hydrothermal Alteration Zones in the Ohekisawa-Shikerebembetsugawa Landslide Area, Hokkaido, Japan

This paper elucidates the relationship between landslides, geologic structures, and hydrothermal alteration zones based primarily on X-ray powder diffraction and uniaxial compressive strength tests on weakly weathered and hydrothermally altered rocks from the Ohekisawa-Shikerebembetsugawa landslide area in Teshikaga Town, Hokkaido, Japan. The OHS （Ohekisawa slide） occurred on a dip slope of sedimentary rocks from the Upper Miocene Shikerepe Formation within a homocline, and also on weathered and hydrothermally altered rocks within the boundary area between the hydrothermal smectite zone and smectite-bearing mordenite zone. The SHS （Shikerebembetsugawa slide） occurred on a dip slope of sedimentary rocks from the Upper Miocene Hanakushibe Formation within wavy folds and was also controlled by a cap rock of Teshikaga Volcano Somma Lava. The SHS occurred also on weathered and hydrothermally altered rocks within the boundary area between the hydrothermal smectite zone and smectite-bearing laumontite zone. The mechanical properties of smectite, smectite-bearing mordenite, and smectite-bearing laumontite zone weakly weathered rocks indicate that they are very weak, soft rocks. These landslides are regarded as HAZLs （hydrothermal alteration zone landslides）. The hydrothermal alteration yielding smectite is thus closely related to these two ancient landslides, suggesting that the potential for HAZLs within a hydrothermal area can be assessed based on the swelling clay mineral-beating hydrothermal alteration types, dip slope, and cap rock.