Smart Nano Clay to Reduce Water-Based Mud Filter Cake

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 drilling-fluid ingredients plays a significant role in generating proper mud cake quality to stabilize wellbore, and avoid formation damage and filtration loss by preventing drilling fluid invasion into the formation. In this study, smart-water drilling mud containing different concentrations of magnetite nanoparticles (MNPs) was used to assess the filtration loss properties and formation impairment. Conventional static filter press, non-destructive X-ray computed tomography (CT) scan images and high-resolution quantitative measurement of CT number method were used to estimate the filtrate volume and characterize the filter cake layers, hence evaluating the reservoir damage through hundreds of merged images. The CT scan data were combined with the HIPAX and Radiant viewer digital image processing. The variation in CT number of mud cake samples under different concentrations of MNPs and without MNPs concentration were analyzed, and hundreds of 3D images as a cross-sectional profile were used. This paper highlights the importance of MNPs property in terms of minimizing filtration volume and improving mud cake quality and thickness, and hence improving the wellbore stability. From the results, a notable reduction of filtrate drilling mud volume and mud cake thickness to 40.9% and 46.6%, respectively, were recorded for drilling fluids incorporated with 0.92 wt.% of MNPs. However, this study asserts that optimal MNPs should be implemented to guarantee the best filtration property. As confirmed from the results, increasing the MNPs concentration beyond the optimal value (up to 2 wt.%) increased the filtrate volume and mud cake thickness by 3.23 and 33.3%, respectively. CT scan profile images show two layers of mud cake produced from water-based drilling fluids possessing 0.92 wt.% MNPs. The latter concentration was found to be the optimal additive of MNPs as it caused a decrease in filtration volume, mud cake thickness, and pore spaces within the structure of the mud cake. Using the optimum MNPs, the CT number (CTN) shows a high CTN and density material, and uniform compacted thin mud cake structure (0.75 mm). The produced thin mud cake layer reveals the precipitation or exchange of elemental/mineral composition during fluid-solid interaction. These results confirm that MNPs could help in avoiding or reducing the formation damage, driving away drilling fluid from the formation, and improving borehole stability.

Lignite, a low-carbon coal variety, is prevalent in numerous global locations. Its application in the oil and gas drilling industry, particularly for controlling pH and fluid loss in aqueous mud systems, has garnered significant attention. Through causticization, lignite can be modified to enhance its performance in these systems. The present study undertakes an assessment of the efficacy of Nigerian lignite in mitigating fluid loss within water-based mud systems. Laboratory analyses were executed in accordance with American Petroleum Institute standards to ascertain the rheological attributes and filtration properties of the developed drilling muds, which contained varying levels of lignite. Furthermore, the performance of the lignite was juxtaposed with that of carboxymethylcellulose (CMC), a traditional fluid loss reduction agent, to elucidate its potential advantages. It was noted that as the lignite concentration escalated from 0.5g to 5g, there was a corresponding reduction in fluid loss, ranging from 0.3ml to 7ml, in contrast to the conventional additive (CMC). Nigerian lignite emerges as an exceptional fluid loss control agent, effectively diminishing the thickness of the mud cake. The integration of Nigerian lignite into water-based drilling fluids led to a significant reduction in both filtrate loss volume and mud cake thickness during drilling activities. The mud cake generated within the water-based mud system incorporating the Nigerian lignite sample was characterized by its thinness and smoothness. Progressive gelation was observed in the mud formulations. Additionally, it is inferred that causticized lignite functions as mud thinner. With increasing lignite concentration, mud viscosities exhibited a decline. Lignite also contributed to the stabilization of the drilling muds’ pH across various concentrations. The mud's pH remained constant at 13. Therefore, it is affirmed that Nigerian lignite possesses the potential to serve as a pH modifier for water-based mud. This research underscores the viability of utilizing locally sourced lignite, fostering sustainable methodologies within the oil and gas sector and potentially diminishing operational expenditures.

Improper drilling fluid parameters may induce a variety of issues, including insufficient cuttings transport, limited solids suspension, poor hole cleaning, and excessive filtrate invasion to the formation. Controlled and optimized drilling fluids rheology is considered the key parameter to solve severe drilling problems encountered during drilling operations. Oil-based muds have numerous applications, but owing to some economic, environmental, and operational challenges, drilling companies are looking for new additives to enhance the characteristics of water-based muds for improved performance. However, the longer exposure of some WBM additives degrades them, which leads to insignificant mud characteristics. In this study, micro-sized naturally occurring agro-material namely cupressus cones powder (CCP) has been assessed as a potential additive in WBM for the first time to enhance the mud performance by improving its rheological and filtration properties. The objective of this study is to prepare a drilling fluid using abundantly available cupressus cones powder and investigate its effects on mud properties. The rheological and filtration characteristics of the drilling muds were determined based on API standards. A series of experiments have been performed to evaluate the impact of CCP loading on the rheology and fluid loss characteristics of drilling mud. The concentration of CCP was varied from 1 to 7 ppb. The findings of rheological characteristics demonstrated that altering the CCP loading enhanced the plastic viscosity, yield point, and gel strength of water-based drilling mud. The optimal concentration for PV was recorded in the range of 2–4 ppb, while the optimum value of YP was obtained at 6 ppb. Moreover, the temperature affected the viscosity and filtration of the mud, whereas the CCP containing muds were found salt resistant. The percent decrease in filtrate volume at 25, 121, and 150 °C was noted as 50, 59.6, and 62%, respectively. The effectiveness of the CCP was also observed from the SEM analysis. This study described the use of a locally available agro-waste material as a potential mud additive.

In this study, the rheological properties and performances of mud prepared with geothermal spring water to be used by geothermal drilling operators were examined at ambient and elevated temperatures. In this context, mud samples were prepared in the compositions detailed in the API specification by using five different geothermal spring water types and a distilled water type. Afterwards, density, apparent viscosity, plastic viscosity, yield point, gel strength, fluid loss, pH, and filter cake thickness of these samples were measured. The drilling muds were analyzed by means of rheological tests in accordance with the standards of the American Petroleum Institute (API). The experimental results have revealed that the mud prepared with geothermal water have lower viscosity and yield point compared to those prepared with freshwater at elevated temperatures. The stability of the muds decreases, especially at temperatures higher than 250°F, and they start to become flocculated. It was concluded that geothermal water-based muds have higher API fluid loss and cake thickness than the freshwater-based one. Therefore, it could be interpreted that the muds prepared with geothermal spring water will exhibit lower flow performance and lower ability of hole cleaning and rate of penetration compared to the freshwater muds. Hence, it is recommended that this kind of water should not be used to prepare drilling mud.

During drilling operations, mud is typically circulated at pressures above the reservoir pressure, and this causes solid particles to deposit along the wellbore creating a mud cake, while the mud filtrate can invade into the formation creating a damaged zone. Near wellbore damage can result in reduced permeability, increased skin and thereby lower productivity of the reservoir, while thick mud cakes can cause issues during drilling including stuck pipe, high torque as well as excessive swab and surge pressures during tripping. These can be prevented by designing the drilling fluid to reduce the quantity of mud filtrate that enters the formation. To facilitate the drilling process, the filter cake that forms should also be thin, uniformly distributed, and stabilized. New techniques such as the use of nanoparticles in the drilling mud, as well as ultrasonication of drilling mud before circulation has demonstrated potential in reducing the filtrate loss into the productive zones, while also optimizing the mud cake formed. This current work studies the effect of adding silicon dioxide (SiO2) particles with spherical morphology and multi-walled carbon nanotubes (MW-CNT) with cylindrical morphology into a water-based drilling fluid sample to improve its filtration characteristics. Systematic ultrasonication of the drilling mud was also conducted to optimize filter cake properties, with the aim to reduce their thickness, while also reducing filtrate loss into the formation. To assess the fluid loss, measurements are made of the filtrate volume, the dry and wet weights, and the filter cake thickness. Based on the experimental results, the amount of filtrate/fluid loss can be decreased with the use of nanoparticles. The weight of the filtrate cake is found to have increased with an increase in nanoparticle loading. Based on filter cake thickness, stability, and porosity estimates of the filter cake, low-concentration SiO2-nanomud (at 1wt%) is observed to be a better candidate than MW-CNT-nanomud to control fluid loss and to maintain wellbore stability. Fluid loss is also observed to be reduced by the ultrasonication process, while the filter cake formed by ultrasonicated drilling mud is thinner and less permeable when compared to an unsonicated sample. Reducing fluid loss is a priority in drilling operations to prevent formation damage and novel techniques such as nanoparticles and ultrasonication can provide optimal results for this issue. The addition of nanoparticles is observed to increase the filtrate cake thickness and reduce the filter cake's porosity, thereby reducing fluid loss. Ultrasonication of drilling mud also produced better filter cake with reduced permeability which in turn reduced fluid loss into the formation.

This study introduces and evaluates an environmentally benign water-based mud (WBM) system using a synergistic combination of polyethyleneimine (PEI) and potassium citrate (PC) as a novel shale swelling inhibitor. The primary objective was to develop a high-performance, greener alternative to conventional potassium chloride (KCl) inhibitor. An extensive experiment was conducted, where WBMs were formulated with varying ratios of PEI and PC, and performance was quantified via fluid loss and mud cake thickness measurements under both low-pressure/low-temperature (LPLT) and high-pressure/high-temperature (HPHT) conditions, alongside linear swell meter analysis over 24 h. The morphological and chemical interactions were investigated using scanning electron microscopy (SEM) and cation exchange capacity (CEC) tests. Results demonstrated a clear synergistic effect, with a formulation of 0.6 v/v% PEI and 0.4 v/v% PC yielding optimal performance. This formulation achieved the lowest fluid loss (8.8 ml/30 min) and the highest mud cake (1.40 mm) under HPHT conditions. Crucially, it suppressed shale swelling by 40.27%, a significant improvement over both the base mud and the traditional KCl inhibitor. The novelty of this PEI-PC system lies in its dual-function mechanism, polymeric encapsulation from PEI combined with the chelating and charge-modifying effects of PC, which provides superior wellbore stability and operational efficiency.

A novel field applicable mud formula with enhanced fluid loss properties in High Pressure-High Temperature well condition containing pistachio shell powder

Reported are the results of an experimental programme to investigate the influence of mud composition, pressure and temperature on the properties of filter cakes formed during static filtration. Three water-based muds were tested at pressures up to 4.2 MPa and temperatures up to 93°C. The spurt loss, cumulative fluid loss, cake thickness and porosity were measured and, using a modified static filtration equation, the cake resistance and compressibility were calculated. The results clearly illustrate the highly compressible nature of filter cakes formed from drilling muds. Also shown is the profound influence of barite and temperature on the cake properties and fluid loss. Using expressions developed in the general field of solid-liquid separation for the variation in porosity within the filter cake, the behaviour of highly compressible cakes under pressure has been illustrated.

The drilling process relies on drilling fluids to create a safe, usable and cost-effective wellbore. Many additives used to maintain drilling fluid properties are non-biodegradable and pose environmental and human health risks. This concern has increased interest in exploring eco-friendly materials as additives in water-based mud. This study investigated the impact of Dry Mango Leaves Powder (DMLP), obtained from the Kent Mango Tree, as an additive in water-based mud. DMLP was prepared by crushing and sieving it to a 75-micron size. Five drilling fluid samples were created: four with different DMLP concentrations (1.75 g to 7.0 g) and one control without DMLP. The samples were aged for 16 hours at room temperature before assessing the mud weight, pH, and filtration characteristics at room temperature and rheological properties at 77 °F (25 °C), 120 °F (48.8 °C) and 150 °F (65.5 °C). The properties were determined by following the standards of the American Petroleum Institute. The results demonstrated that DMLP effectively reduced alkalinity by 25.2% at a concentration of 7.0g. Rheological values and plastic viscosity decreased with increasing DMLP concentration at 77 °F, 120 °F and 150 °F, though there were no significant changes in the yield point. The addition of DMLP improved gel strengths with the difference in the final and initial gel strength staying below lb/100ft² at all concentrations and temperatures, except for a concentration of 1.75 g at 77 °F. The addition of 7.0 g of DMLP reduced the fluid loss by 22.4%. Although DMLP showed potential in improving gel strength and fluid loss, its effectiveness as a weighting agent remains limited. This study demonstrates the potential of DMLP as an eco-friendly additive to enhance certain properties of water-based mud, making it a promising alternative for sustainable drilling operations.

A novel approach to enhance rheological and filtration properties of water–based mud using polypropylene–silica nanocomposite

In drilling operations, polymers such as carboxymethyl cellulose and polyanionic cellulose (PAC) are frequently employed as additives to decrease filtrate loss in water-based drilling fluids. In some countries these additives are imported requiring the use of the Nation’s scare foreign exchange and increase in the Capital expenditure of the drilling operation. Consequently, cheap, and easily accessible local materials that can perform a similar role are being considered. In lieu of this reality, a composite mix of sawdust and coconut fiber, was assessed as a potential additive for fluid loss control in water-based drilling mud, and the outcomes were compared with carboxymethyl cellulose (CMC), sawdust only additive, and coconut fiber only additive. Furthermore, in order to ascertain the best combination ratio for the sawdust and coconut fiber for optimum fluid loss control, the study experimented on three combinations of 50% and 50%; 75% and 25% and 25% and 75% in a 5g concentration of 350ml water-based mud. The result shows the composite combination of 75% sawdust and 25% coconut fiber produce the best data for fluid loss control among the composite samples. A comparison of the result with a 2.5g of CMC showed that while CMC sample had a better fluid loss of 12.3ml, the best composite sample had a fluid loss of 14.5ml; a slight difference of 2.2ml. In addition, the effect of the composite mix of sawdust and coconut fiber on the pH, density, and mud cake thickness of the water-based mud was evaluated in the laboratory and the result were presented and it showed that the composite samples had an incremental effect on the pH, and density of the water-based mud.

Drilling mud’s rheological characteristics, such as plastic viscosity and yield point, are adversely affected with an inappropriate mud formulation. Native starch is one of the most important components in water-based mud because it improves the rheological and filtration characteristics of the mud. The native starch stability under various temperature and exposure time regimes is an important concern for utilizing starch in oil and gas drilling operations. In this work, tapioca starch was modified using carboxymethylation for the first time in order to improve its performance in non-damaging water-based muds. The modified starch was characterized by Fourier-transform infrared spectroscopy and X-ray diffraction. The thermal stability was tested using thermal gravimetric analysis. Various mud blends were formulated based on the experimental design using response surface methodology (RSM) to investigate their performance at various temperature conditions. Thirty experimental runs were carried out based on the selected factors and responses considering the optimal (custom) design, and the results were analyzed through ANOVA. The Fourier-transform infrared spectroscopy and X-ray diffraction results confirmed the carboxymethylation of starch. The TGA analysis revealed strong thermal stability after modification. Additionally, the Power law model (PLM) described the obtained rheological data for the selected formulations, resulting in determination coefficients of more than 0.95. Furthermore, the examined samples showed a reduction in the flow behavior index from 0.30 to 0.21 and an increase in the consistency index from 5.6 to 15.1. Optimization and confirmation results revealed the adequacy of the generated empirical models for both plastic viscosity and yield point. The obtained consistency index values provided a direct relationship with the modified starch concentration, indicating an improvement in the cutting carrying capacity of mud. Based on the current literature survey, the studied formulation has not been reported in the literature.

Developing high-performance environmentally friendly drilling fluids is always a requirement by oil and gas operators to reduce the waste management associated cost with the drilling fluid treatment and disposal. Conventional water-based drilling fluid is formulated with the brine-based polymer which consists of sodium and potassium chloride salts to improve the performance of the polymer and also providing clay inhibition in reactive clay and shale. This paper describes the development of nanotechnology-based drilling fluid to replace salt from the conventional application. Nano Based Low Saline Water Based Mud (NBLS-WBM) was formulated and developed based on laboratory experiments. Different nano additives with different concentrations were evaluated and the optimum concentration was selected to reduce the sodium and potassium chloride salts concentration to almost zero. The rheological properties and fluid loss were measured according to the API standard before and after hot rolling. Also, HPHT fluid loss, lubricity, and shale inhibition were evaluated. All the results were compared with sodium salt-saturated and potassium-based polymer muds. Laboratory evaluation of NBLS-WBM indicated that sodium salt concentration can be reduced considerably up to 5% W/V and potassium chloride can be eliminated by adding 1% W/W of nano additive. The rheological properties including plastic viscosity and yield point were constant and stable after hot rolling 16 hours at 250 °F. Also, Clay inhibition improved significantly up to 95% recovery comparing with conventional water-based polymer mud. Although the application of nanotechnology to improve the performance of conventional water-based drilling fluid was studied by many researchers, it is the novelty of this research to reduce the salt concentration and remove it to develop the new generation of salt-free water-based drilling fluid with economical consideration and lower environmental impact.

This paper presents results from novel tests investigating screen plugging and the factors that influence it. The study focuses on sand retention and flow convergence into screens, assuming formation collapse. Controlled experiments were conducted to evaluate the performance of different screens and the role of sand in plugging. The tests also explore how drilling and completion processes affect screen performance and plugging behavior. A novel test procedure was developed to simulate sand retention on screens. Screens with retained sand were placed in a flow apparatus to study multiphase flow behavior. A mix of sand and fines slurry was used to evaluate screen and near-screen plugging. The effect of mud and filter cake was assessed by allowing cake formation on the sand face before flowing. Additionally, the influence of temperature—up to 200°C—was examined to understand thermal impacts on screen plugging mechanisms under realistic downhole conditions. This study utilized three Particle Size Distribution (PSD) classes from the McMurray Formation to represent common variations in thermal project sands. A common polymeric mud, representative of the mud system used in thermal drilling, was employed. The thickness of the mud cake varied significantly among the three sands and was directly related to their permeability, with finer sands forming denser cakes that reduced retained permeability by over 55% in the lowest permeability class. Experiments during the drawdown phase revealed that wire-wrapped screens outperformed punch screens in permeability recovery due to enhanced channeling, with coarser PSDs showing better restoration (up to 72% retention). Thermal exposure at 200°C, intended to break down polymers, instead densified the cake with residue deposition, reducing post-steaming permeability by 5-30% depending on PSD, though wire-wrapped screens with 100-150 μm slots mitigated losses. Plugging occurred primarily at the sand-cake interface, emphasizing the need for near-screen management. These findings support preventive measures to minimize plugging and optimize thermal performance. This study aims to help engineers understand the key factors influencing screen plugging and the resulting high differential pressure drop between injectors and producers. The insights gained support the implementation of preventive measures to avoid or minimize screen plugging, improving overall system performance and reliability.

Experimental evaluation of nanomaterials to improve drilling fluid properties of water-based muds HP/HT applications