Search Results (8)

Polymers derived from renewable polysaccharides offer promising avenues for the development of high-temperature, environmentally friendly drilling fluids. However, their industrial application remains limited by inadequate thermal stability and poor colloidal compatibility in complex mud systems. In this study, we report the rational design and synthesis of epichlorohydrin-crosslinked carboxymethyl xylan (ECX), developed through a synergistic strategy combining covalent crosslinking with hydrophilic functionalization. When incorporated into water-based drilling fluid base slurries, ECX facilitates the formation of a robust gel suspension. Comprehensive structural analyses (FT-IR, XRD, TGA/DSC) reveal that dual carboxymethylation and ether crosslinking impart a 10 °C increase in glass transition temperature and a 15% boost in crystallinity, forming a rigid–flexible three-dimensional network. ECX-modified drilling fluids demonstrate excellent colloidal stability, as evidenced by an enhancement in zeta potential from −25 mV to −52 mV, which significantly improves dispersion and interparticle electrostatic repulsion. In practical formulation (1.0 wt%), ECX achieves a 620% rise in yield point and a 71.6% reduction in fluid loss at room temperature, maintaining 70% of rheological performance and 57.5% of filtration control following dynamic aging at 150 °C. Tribological tests show friction reduction up to 68.2%, efficiently retained after thermal treatment. SEM analysis further confirms the formation of dense and uniform polymer–clay composite filter cakes, elucidating the mechanism behind its high-temperature resilience and effective sealing performance. Furthermore, ECX demonstrates high biodegradability (BOD₅/COD = 21.3%) and low aquatic toxicity (EC₅₀ = 14 mg/L), aligning with sustainable development goals. This work elucidates the correlation between molecular engineering, gel microstructure, and macroscopic function, underscoring the great potential of eco-friendly polysaccharide-based crosslinked polymers for industrial gel-based fluid design in harsh environments. Full article

Sodium-based bentonite is used for drilling operations because of its high swelling capacity. This type of bentonite clay is not sourced locally in many oil- and gas-producing nations. However, low-swelling clays (calcium- and potassium-based) are in abundant quantities in most of these countries. Hence, there is a need to convert low-swelling bentonite clays to sodium-based bentonite. The method used to convert low-swelling clays is more applicable to calcium-based bentonite. This research investigated a thermochemical treatment method that converted potassium-based bentonite to sodium-based bentonite. The raw clay materials were sourced from Pindinga (P) and Ubakala (U) clay deposits in Nigeria. An X-ray diffractometer (XRD), an energy dispersive X-ray (EDX), and a scanning electron microscope (SEM) were used to characterize the raw clay samples. Mud slurry was prepared by mixing 22 g of the local raw clays, 3 wt.% soda ash, and MgO at concentrations between 1 and 3 wt.% and heating at 90 °C. The result showed that the viscosities of samples P and U increased from 6 to 26 and 8 to 35.5 cP before and after thermochemical treatment, respectively. Also, due to the thermochemical treatment, the samples’ yield point, consistency factor, consistency index, and thixotropy behavior were all significantly improved. Full article

The flocculation–solidification–filter-press combined method is a new type of method for treating waste slurry that combines flocculation and chemical curing with a mechanical filter press. Among these processes, the mechanical filter-press process is key to the efficient disposal of waste engineering slurries by the flocculation–solidification–filter-press combined method. In the mechanical filter-press process, parameters including the initial thickness of filtration mud, the magnitude of filtration pressure, and the duration of press filtration have important impacts on the dewatering and strength after subsequent curing. In this work, a series of laboratory tests were conducted to study the influence of filter-press parameters on flocculated–solidified mud by measuring the properties of treated and cured mud. The test results showed that the initial mud bag thickness is an important factor in the mud treatment effect. As the initial mud bag thickness increases, the greater the water content of the mud at the end of the filter-press process after applying the same amount of time and the same amount of pressure, the lower the post-conservation strength will be. The increase in filtration pressure and filtration time within a certain range can reduce the water content of the mud brick after filtration and significantly improve its shear strength. In the actual process of filtering in the project, the thickness of the initial mud bag should be no more than 140 mm, the filtration pressure is about 0.35 MPa, and the filtration time is suitable for 2 min. Full article

A pressure filtration–flocculation–solidification combined treatment possesses great potential for the reutilization of the waste mud slurry generated from diverse construction projects as filling material due to its versatility and high efficiency. However, very limited existing studies have focused on the factors affecting pressure filtration’s efficiency. In this paper, a calculation model for compression filtration is established based on laboratory pressure filtration model tests and one-dimensional large-strain consolidation theory. The influence of various parameters on pressure filtration’s efficiency is analyzed, and favorable values for these parameters are recommended. The results show that an increased initial mud cake thickness significantly increases the dewatering time and reduces the treatment’s efficiency. A lower dewatering time and higher efficiency can be achieved by increasing the filtration pressure, but the efficiency improvements become limited after reaching the critical pressure threshold. For the mud slurry used in this study, the optimal values for the initial mud slurry bag thickness, filtration pressure, and dewatering time are 240 mm, 1.0 MPa, and 30 min, respectively, yielding a final mud cake water content of 58.7% after filtration. Full article

The accumulation of residue soil (generally composed of soil, residue, or mud consolidation) is one of the important causes of damage to the environment limiting urban development. At present, the recycling rate of residue soil in developed countries is as high as 90%, while in China it is less than 5%. In marine construction, reinforced concrete often suffers from corrosion, which leads to a decrease in the service life and durability of the structure. Reactive powder concrete (RPC) with high strength and good corrosion resistance can solve these problems. In order to efficiently dispose of residue soil, protect the environment, and promote urbanization development, this study uses residue soil as a raw material to replace some cement in RPC, and studies the corrosion resistance of it (under dry–wet alternations and freeze–thaw cycles). In this study, five types of reinforced RPC with different residue soil contents (0%, 2.5%, 5%, 7.5%, and 10%) are prepared. Firstly, the working performance of blank freshly mixed residue soil RPC slurry is analyzed. Then, the corrosion resistance of residue-soil-reinforced RPC under the dry–wet alternations with 3% NaCl and freeze–thaw cycles is analyzed through parameters such as mass loss rate, electrical resistivity, ultrasonic velocity, AC impedance spectroscopy, and Tafel. The results show that under the dry–wet alternations, when the residue soil content is 10%, the corrosion rate and corrosion depth of the residue-soil-reinforced RPC are the minimum, at 43,744.84 g/m²h and 640.22 mm/year, respectively. Under the freeze–thaw cycles, the corrosion rate and corrosion depth of the 10% residue soil content group are higher than that of the 5%, being 52,592.87 g/m²h and 769.71 mm/year, respectivley. Compared to the other groups, the reinforced RPC with 10% residue soil content shows good corrosion resistance in both dry–wet alternations and freeze–thaw cycles. Replacing some of the cement in RPC with residual soil to control the amount of residual soil at 10% of the total mass of RPC can effectively improve the corrosion resistance of residue-soil-reinforced RPC and maximize the consumption of residue soil. This plan provides a feasible method for residue soil treatment in the construction industry, while also providing inspiration for research on the corrosion resistance of concrete in marine buildings. Full article

When large-diameter slurry shields are tunneling in a composite stratum with a high clay content, the cutter head may form a mud cake. After the mud cake is formed, it will cover the cutter and reduce the opening rate of the cutter head, thus reducing the penetration of the cutter and the driving speed. Based on a road upgrading project, this paper studies the prevention and treatment of a mud cake and forms a set of comprehensive treatment methods. For a large mud cake, through theoretical analysis, two calculation methods of the cutter head sealing coefficient are obtained, and the cutter head sealing coefficient relationship model is established. Comparing the calculated cutter head’s actual opening coefficient with the required cutter head opening coefficient can provide a judgment basis for the time of manual warehousing. For medium and small mud cakes, the numerical simulation is carried out based on the cutter head and the scouring system, the distribution characteristics of the flow field near the cutter head are analyzed, and the angle of the central scouring hole is optimized. For a small mud cake, hydrogen peroxide is selected as an additive through microscopic mechanism analysis. The effect of the hydrogen peroxide solution concentration on dissolving a mud cake is obtained through laboratory tests, and its effectiveness is verified through field tests. The research results can provide a reference for the mud cake prevention of slurry shields in similar strata. Full article

Traditionally, the drilling waste generated in oil and gas exploration operations, including spent drilling fluid, is disposed of or treated by several methods, including burial pits, landfill sites and various thermal treatments. This study investigates drilling waste valorisation and its use as filler in polymer composites. The effect of the poor particle/polymer interfacial adhesion bonding of the suspended clay in oil-based mud (OBM) slurry and the LDPE matrix is believed to be the main reason behind the poor thermo-mechanical and mechanical properties of low-density polyethylene (LDPE)/OBM slurry nanocomposites. The thermo-mechanical and mechanical performances of LDPE)/OBM slurry nanocomposites without the clay surface treatment and without using compatibilizer are evaluated and discussed. In our previous studies, it has been observed that adding thermally treated reclaimed clay from OBM waste in powder form improves both the thermal and mechanical properties of LDPE nanocomposites. However, incorporating OBM clay in slurry form in the LDPE matrix can decrease the thermal stability remarkably, which was reported recently, and thereby has increased the interest to identify the mechanical response of the composite material after adding this filler. The results show the severe deterioration of the tensile and flexural properties of the LDPE/OBM slurry composites compared to those properties of the LDPE/MMT nanocomposites in this study. It is hypothesised, based on the observation of the different test results in this study, that this deterioration in the mechanical properties of the materials was associated with the poor Van der Waals force between the polymer molecules/clay platelets and the applied force. The decohesion between the matrix and OBM slurry nanoparticles under stress conditions generated stress concentration through the void area between the matrix and nanoparticles, resulting in sample failure. Interfacial adhesion bonding appears to be a key factor influencing the mechanical properties of the manufactured nanocomposite materials. Full article

The loss of circulation is a big problem in drilling operations. This problem is costly, time-consuming and may lead to a well control situation. Much research has investigated the effectiveness of using different chemicals as lost circulation material (LCM) to stop mud and cement slurry losses. However, there remain many limitations for using such LCM types, especially when it comes to field applications. This paper presents a new high strength lost circulation material (HSLCM) that could effectively be used for managing severe lost circulation cases. The HSLCM could easily be pumped into the thief zone where it forms a gel that solidifies after a setting time to provide sealing between the wellbore and the thief zone. With this technique, the material stops the circulation losses, and hence enhances the well bore stability by reducing the well bore stresses. The HSLCM has a high compressive strength and it has a high acid solubility of around 96%. Because the HSLCM has high tolerance towards contamination, it can be utilized with water-based mud or invert emulsion-drilling fluids, hence providing a wide window of applications with the drilling fluids. In this study, laboratory experiments were conducted to evaluate the rheology, thickening time, compressive strength, and acid solubility of the HSLCM. The results showed good performance for the HSLCM as LCM. In addition, a case field study is presented which shows a successful field treatment for severe losses. Full article