Improving the performance of oil based mud and water based mud in a high temperature hole using nanosilica nanoparticles

An experimental investigation into the rheological behavior and filtration loss properties of water-based drilling fluid enhanced with a polyethyleneimine-grafted graphene oxide nanocomposite

The modern oil and gas industry, driven by a surging global energy demand, faces the challenge of exploring deeper geological formations. Ensuring the robust performance of drilling fluids under harsh wellbore conditions is paramount, with elevated temperatures and salt contamination recognized as detrimental factors affecting the rheological and filtration loss properties of drilling fluids. We successfully synthesized a polyethyleneimine-grafted graphene oxide nanocomposite (PEI-GO), and its functional groups formation and thermal stability were verified through Fourier Transform Infrared Spectroscopy (FTIR) and Thermogravimetric Analysis (TGA). Our findings demonstrated a significant improvement in the plastic viscosity and yield point of the base drilling fluid with the addition of PEI-GO. The inclusion of 0.3 wt% PEI-GO outperformed the base drilling fluid at 160 °C, improving the yield point/plastic viscosity (YP/PV) value and reducing filtration loss volume by 42% and 67%, respectively. The Herschel-Bulkley model emerged as the superior choice for characterizing rheological behavior. PEI-GO exhibited compatibility with high-salt formations, maintaining satisfactory filtration volumes even when subjected to sodium chloride (NaCl) and calcium chloride (CaCl2) contamination concentrations of up to 20 and 10 wt%, respectively. The remarkable rheological and filtration properties of PEI-GO are attributed to its electrostatic interactions with clay particles through hydrogen and ionic bonding. These interactions lead to pore plugging in the filter cake, effectively preventing water infiltration and reducing filtration loss volume. This study emphasizes the potential of PEI-GO in water-based drilling fluids, particularly in high-temperature and salt-contaminated environments.

Analyzing the performance of synthesized nano-catalysts for transesterification of waste cooking oil as environment friendly drilling fluid

Ester-based drilling fluids (EBDF) are preferred over oil-based drilling fluids (OBDF) and water-based drilling fluids (WBDF) because of their great biodegradability, low toxicity, and improved performance. In this work, waste cooking oil methyl ester (WCOME) was used to prepare an environmentally friendly EBDF. Through a transesterification process utilizing a modified calcium oxide based heterogenous catalyst, the waste cooking oil is transformed into waste cooking oil methyl ester. Response surface approach was used to strengthen the transesterification. The optimize conditions for CaO/Al2O3 resulted in the highest yield of 96.56% at a molar ratio of 11.9:1, 3.19 wt % of CaO/Al2O3, 53.79 °C, and 76.86 min. In contrast, CaO/TiO2 yielded 98.15% at a molar ratio of 11.99:1, with a CaO/TiO2 of 2.53 wt % at 59.79 in 68.14 min. Additionally, two separate densities of 9 ppg and 12 ppg EBDF are formulated with two distinct oil-to-water ratios (70:30 and 80:20) using synthesized WCOME. To assess the effectiveness of formulated EBDF thorough rheological investigation is conducted at 150°. Additionally, the filtration loss at HPHT conditions, emulsion stability, and Barite sag analysis of the drilling fluid are all analyzed at before ageing and after dynamic ageing. With better rheological features, less fluid loss, good emulsion stability, and minimal barite sagging, the designed EBDF performs efficiently. The drilling fluid met the API requirement and demonstrated stability even after ageing at 250 °F for 72 h, suggesting that it may be used for extended periods of time in drilling.

Experimental Investigation of Using Manganese Monoxide as a Hydrogen Sulfide Scavenger for Aqueous Drilling Fluids

One of the most serious safety and health concerns during drilling oil and gas wells is the potential release of hydrogen sulfide (H2S) to the surface, exposing workers to high risks. Serious corrosion-related damage to handling equipment is also inevitable in the presence of H2S. Various H2S scavengers have been utilized, but each has its pros and cons; hence, research is continuing to develop an optimum and feasible scavenger. Since manganese monoxide (MnO) is a reactive metal oxide with high oxidation and absorption capabilities, it may have the potential to effectively scavenge H2S during drilling operations when included in drilling mud formulations. Consequently, the key aim of this work is to investigate the H2S scavenging performance of the aqueous drilling fluid containing MnO. This work studied the impact of MnO addition on the drilling mud's alkalinity, rheological behavior, filtration performance, and corrosion tendency. The experiments were also conducted for mud without a scavenger and a fluid containing the SourScav commercial scavenger, which serves as a benchmarking reference. The findings demonstrated that MnO performed exceptionally well for H2S scavenging where it boosted the aqueous mud's scavenging capacity from 84.3 to 426.2 mg of H2S/L of mud, showing more than 400% improvement relative to the base mud. Additionally, this scavenging performance is about 2.1 times higher than that of the commercial scavenger. As opposed to SourScav, MnO maintained the mud's pH at a safe level above 10. The addition of either MnO or SourScav did not weaken the mud rheology and provided practically satisfactory rheological parameters. Both SourScav and MnO marginally increased the formed filter-cake thickness from 2.9 to 3.9 mm with a slight increment in the filtrated volume but still within the acceptable limits. The corrosion test indicated the noncorrosive characteristics (i.e., the corrosion rate was nearly zero) of MnO and the commercial scavenger. This study illustrates the promising utilization of MnO as a cost-effective H2S scavenger, enhancing the efficiency and safety of drilling operations.

Primary Investigation of Barite-Weighted Water-Based Drilling Fluid Properties

Drilling fluid is a critical component in drilling operation due to its various functions. It consists of many elements, and one of the main components is the weighting material which controls the mud density. The weighting material type and concentration have a significant impact on the drilling fluid properties. A common weighting material used in the oil and gas industry is barite. In this work, the impact of barite concentration on water-based drilling fluid was evaluated. The investigated drilling fluid properties are density, pH value, filtration behavior, and rheological parameters. An intense investigation was carried out to evaluate the impact of barite concentration on the filtration and filter cake sealing properties. The density and pH values were measured at room temperature, filtration test was performed at room temperature, and differential pressure was equal to 100 psi. The rheological parameters were determined after hot rolling for 16 h at a temperature of 250 °F. The results showed that both the density and pH value increased linearly with barite dosage. The filtration volume, filter cake thickness, and permeability increased with the incremental increase in barite dosage, and the exponential relationship was the best in describing the relation with barite concentration. However, the filter cake porosity had an inverse proportional relation with barite dosage. In the case of rheological properties, all the investigated properties including the plastic viscosity, yield point, ratio of yield point to plastic viscosity, and gel strength at two different times (i.e., 10 s and 10 min) increased in general as the barite concentration increased.

Improving the filtration properties for manganese tetroxide mud utilizing perlite particles to drill wide-range permeability sandstone formation

A required feature of any drilling formulation is to mitigate the formation damage by having an excellent filtration and filter cake properties. The key factor for preventing and limiting formation damage is to improve the sealing qualities of the planned drilling fluid. In this study, a new novel filtration agent called "perlite" was introduced for improving the manganese tetroxide mud cake ability for better sealing features. The perlite particles were loaded to formulation containing the manganese tetroxide as weighting agent. The water-based drilling mud was designed at high densities (14.25 and 17.2 ppg). Perlite was added in varied concentrations to reach the optimum performance. The filtration test conducted at reservoir temperature of 250 °F and a differential pressure of 300 psi to form the filter cake. The tests were performed using sandstone cores with two different permeability categories (low and high permeabilities) as the filtration media. This gave the full picture of perlite performance as implemented for different formation properties and considering the drilling fluid properties. The formed filter cake structure and chemical composition was evaluated using scanning electron energy-dispersive X-ray (SEM-EDS). The presented results illustrated how the perlite was compatible to be added to the manganese tetroxide weighting agents in the same formulation. In addition, it has the capacity to improve the filter cake's sealing qualities, lowering the filtration volume by 41% and the filter cake internal and external layers permeability by 58% and 25%, respectively. Moreover, the EDS analysis showed that the perlite particles are concentrated generally in the internal layer of the filter cake.

Role of Rock Saturation Condition on Rock-Mud Interaction: Sandstone Geomechanics Study

The rock saturation condition affects the rock elastic and strength characteristics due to the role of fluid-rock interaction. However, the role of this parameter has not been studied well for mud-rock exposure during drilling operations. Hence, this study targets to assess the role of different rock saturation conditions on the rock geomechanics changes during the rock exposure for the drilling fluids. During the drilling operation, the mud filtrate invades the drilled formation pore system and replaces the saturating fluid and consequent alterations occur for the rock elastic moduli and failure properties. The current study employed Berea Buff sandstone rock type with different saturation conditions (brine-saturated, dry, and oil-saturated) to interact with drilling mud (water-based) through the filtration test to mimic the downhole rock-mud exposure under pressure, temperature, and time conditions. Extensive laboratory analysis was accomplished that covered the scratching test to get the strength of rock samples, acoustic data determination, elastic moduli evaluation, and scanning electron microscopy to assess the internal alterations of the rock pore system. The obtained results showed that the oil-saturated sample showed the least filtration characteristics for the rock-mud exposure and the best condition to maintain the rock strength from deterioration compared to the dry and brine-saturated samples. The rock strength showed a weakening behavior for the brine-saturated and dry samples by 5 and 18% respectively, while the oil-saturated sample showed only a 2% strength reduction after the mud exposure. Poisson's ratio showed a 21% increase for the brine-saturated sample and the dry sample showed a small increase from 0.2 to 0.22, while the oil-saturated sample maintains a stable Poisson's ratio at 0.24. Young's modulus showed an increase for the dry and brine-saturated rock samples by 10 and 7%, respectively, while a 25% reduction for the oil-saturated. The spectrometry analysis results showed the internal changes in the rock samples' pore system for the brine-saturated and dry samples, while the oil-saturated sample showed no internal changes that maintain the rock structure and strength after the mud exposure.

The role of overbalance pressure on mud induced alteration of sandstone rock pore system

Overbalance pressure is a very critical parameter in drilling operations. It has a great impact on formation damage, depending on other downhole parameters such as temperature, time, type and composition of mud, and rock mineralogical content. The objective of this study is to determine the degree of the impact of overbalance pressure on mud-rock interaction and the resultant effects on the rock pore system. This research presents an experimental study for the interaction of a Berea Buff sandstone and barite water-based under different overbalance pressure (300, 700, and 1000 psi) under the same temperature and interaction time. The experiments involved the use of the scanning electron microscope and nuclear magnetic resonance relaxation measurements to monitor changes in the pore system of the rock samples. A modified filtration cell was used to accommodate the rock samples and mud at different overbalance pressures. The obtained results showed that the filtration properties, rock flow characteristics (rock permeability, pore throat radius, and pore system scale type) are all affected by increasing the overbalance pressure. The filtration properties increased in terms of mud cake thickness and filtrate volume by 111% and 36% respectively when the overbalance pressure was increased from 300 to 1000 psi. The total rock porosity showed a decrease from 21.6% (pre-mud interaction) to 17.6, 15.2, and 14.2% under 300, 700, and 1000 psi, respectively. The rock permeability decreased by 75% under 1000 psi overbalance pressure while pore throat radius decreased by 45%. However, the rock pore type remains on the same scale (Macro) after interaction with the mud. Statistical analysis showed that the rock porosity and permeability decreased with the overbalance pressure increase through a polynomial relationship with a high determination coefficient of 0.99. Analysis of the internal pore system by the scanning electron microscope showed that the formation damage is mainly attributed to the precipitations of mud solids as overbalance pressure is increased.

Effect of core-shell nanocomposites on the mechanical properties and rheological behaviors of cement pastes

SiO₂ nanoparticles (50 nm in diameter) coated with poly(ethylene glycol) methyl ether methacrylate (PEGMA) were synthesized by radical polymerization. The SiO₂/PEGMA nanocomposites were characterised using FITR, ¹HNMR and TGA methods. The load of PEGMA in SiO₂/PEGMA nanocomposites was 72.9 wt%. The hydration products, microstructure, pore structure, density, compressive strengths and rheological properties of cement were investigated. The SiO₂/PEGMA nanocomposite could not only significantly improve the cement hydration and densify the microstructure by reducing the content of calcium hydroxide and promoting the production of calcium silicate hydrate, but also efficiently enhance the fluidity of the cement slurry. The compressive strength of cement with 2 wt% SiO₂/PEGMA nanocomposites was increased by 40.1% curing for 28 days, which was much better than cement with the physical blending of SiO₂ nanoparticles and superplasticizers. The SiO₂/PEGMA nanocomposites with core-shell structure novelly combine the advantages of SiO₂ nanoparticles and superplasticizers to significantly improve the performance of cement pastes. The results obtained provide a new understanding of the effect of the core-shell nanocomposites on cement pastes and demonstrate the potential of the nanocomposites for well cementing applications.

The Role of Drilled Formation in Filter Cake Properties Utilizing Different Weighting Materials

The filter cake formed during a filtration process plays a vital role in the success of a drilling operation. There are several factors affecting the filter cake build-up such as drilled formation, drilling fluid properties, and well pressure and temperature. The collective impact of these two factors (i.e., formation and the drilling fluid) on the filter cake build-up needs to be fully investigated. In this study, two types of formations represented as limestone and sandstone were used with different weighting materials to assess and compare their impact on the filter cake properties, filtration behavior, and solid invasion. The used weighting materials are manganese tetroxide, ilmenite, barite, and hematite. The filter cake was formed under a temperature of 200 °F and differential pressure of 300 psi. Nuclear magnetic resonance spectroscopy was employed to explore the pore structure of the used core samples. The results showed that the properties (i.e., shape and dimensions) of the different weighting materials are the dominant factors compared to the formation characteristics in most of the investigated filter cake properties. Nevertheless, the formation properties, namely, the permeability and pore structure, have a somehow higher contribution when it comes to the filter cake porosity and thickness. For solid invasion, there were no clear results about the main factor contributing to this issue.

Experimental Investigation of the Rheological Behavior of an Oil-Based Drilling Fluid with Rheology Modifier and Oil Wetter Additives

Drilling issues such as shale hydration, high-temperature tolerance, torque and drag are often resolved by applying an appropriate drilling fluid formulation. Oil-based drilling fluid (OBDF) formulations are usually composed of emulsifiers, lime, brine, viscosifier, fluid loss controller and weighting agent. These additives sometimes outperform in extended exposure to high pressure high temperature (HPHT) conditions encountered in deep wells, resulting in weighting material segregation, high fluid loss, poor rheology and poor emulsion stability. In this study, two additives, oil wetter and rheology modifier were incorporated into the OBDF and their performance was investigated by conducting rheology, fluid loss, zeta potential and emulsion stability tests before and after hot rolling at 16 h and 32 h. Extending the hot rolling period beyond what is commonly used in this type of experiment is necessary to ensure the fluid's stability. It was found that HPHT hot rolling affected the properties of drilling fluids by decreasing the rheology parameters and emulsion stability with the increase in the hot rolling time to 32 h. Also, the fluid loss additive's performance degraded as rolling temperature and time increased. Adding oil wetter and rheology modifier additives resulted in a slight loss of rheological profile after 32 h and maintained flat rheology profile. The emulsion stability was slightly decreased and stayed close to the recommended value (400 V). The fluid loss was controlled by optimizing the concentration of fluid loss additive and oil wetter. The presence of oil wetter improved the carrying capacity of drilling fluids and prevented the barite sag problem. The zeta potential test confirmed that the oil wetter converted the surface of barite from water to oil and improved its dispersion in the oil.

Preparation of Ammonium Oleic Acid Salts and Their Evaluation as Shale Swelling Inhibitors in Water-Based Drilling Fluid

In this paper, ammonium oleic acid salts (AOS) were prepared from oleic acid and amines and investigated as low molecular weight shale swelling inhibitors. First, the inhibitory effect of AOS was investigated using the linear expansion test of bentonite. The results show that the inhibitor prepared from oleic acid and tetraethylene pentamine with a molar ratio of 1:2 (AOS-8) has an excellent inhibitory effect on the hydration expansion of bentonite. The inhibitory effect of AOS-8 on bentonite was further investigated in subsequent work steps using various methods, including the linear swelling test of clay and particle distribution measurement. The results show that AOS-8 has superior performance in inhibiting hydration swelling and dispersion of bentonite. With 0.5% AOS-8, the swelling rate was reduced to 37.7%, and the particle size of bentonite in water could be controlled with AOS-8. Finally, the inhibition mechanism of AOS-8 was determined in detail by scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). In water-based drilling fluid, AOS-8 is compatible with conventional additives. It can also significantly improve the lubricating capacity of the mud cake after ageing at 120°C.

Utilization of Eco-Friendly Waste Generated Nanomaterials in Water-Based Drilling Fluids; State of the Art Review

An important aspect of hydrocarbon drilling is the usage of drilling fluids, which remove drill cuttings and stabilize the wellbore to provide better filtration. To stabilize these properties, several additives are used in drilling fluids that provide satisfactory rheological and filtration properties. However, commonly used additives are environmentally hazardous; when drilling fluids are disposed after drilling operations, they are discarded with the drill cuttings and additives into water sources and causes unwanted pollution. Therefore, these additives should be substituted with additives that are environmental friendly and provide superior performance. In this regard, biodegradable additives are required for future research. This review investigates the role of various bio-wastes as potential additives to be used in water-based drilling fluids. Furthermore, utilization of these waste-derived nanomaterials is summarized for rheology and lubricity tests. Finally, sufficient rheological and filtration examinations were carried out on water-based drilling fluids to evaluate the effect of wastes as additives on the performance of drilling fluids.

Doxorubicin-Loaded Gold Nanoarchitectures as a Therapeutic Strategy against Diffuse Intrinsic Pontine Glioma

Diffuse Intrinsic Pontine Gliomas (DIPGs) are highly aggressive paediatric brain tumours. Currently, irradiation is the only standard treatment, but is palliative in nature and most patients die within 12 months of diagnosis. Novel therapeutic approaches are urgently needed for the treatment of this devastating disease. We have developed non-persistent gold nano-architectures (NAs) functionalised with human serum albumin (HSA) for the delivery of doxorubicin. Doxorubicin has been previously reported to be cytotoxic in DIPG cells. In this study, we have preclinically evaluated the cytotoxic efficacy of doxorubicin delivered through gold nanoarchitectures (NAs-HSA-Dox). We found that DIPG neurospheres were equally sensitive to doxorubicin and doxorubicin-loaded NAs. Colony formation assays demonstrated greater potency of NAs-HSA-Dox on colony formation compared to doxorubicin. Western blot analysis indicated increased apoptotic markers cleaved Parp, cleaved caspase 3 and phosphorylated H2AX in NAs-HSA-Dox treated DIPG neurospheres. Live cell content and confocal imaging demonstrated significantly higher uptake of NAs-HSA-Dox into DIPG neurospheres compared to doxorubicin alone. Despite the potency of the NAs in vitro, treatment of an orthotopic model of DIPG showed no antitumour effect. This disparate outcome may be due to the integrity of the blood-brain barrier and highlights the need to develop therapies to enhance penetration of drugs into DIPG.

Effect of Iron Oxide Nanoparticles on the Properties of Water-Based Drilling Fluids

In recent years, several studies have indicated the impact of nanoparticles (NPs) on various properties (such as viscosity and fluid loss) of conventional drilling fluids. Our previous study with commercial iron oxide NPs indicated the potential of using NPs to improve the properties of a laboratory bentonite-based drilling fluid without barite. In the present work, iron oxide NPs have been synthesized using the co-precipitation method. The effect of these hydrophilic NPs has been evaluated in bentonite and KCl-based drilling fluids. Rheological properties at different temperatures, viscoelastic properties, lubricity, and filtrate loss were measured to study the effect of NPs on the base fluid. Also, elemental analysis of the filtrate and microscale analysis of the filter cake was performed. Results for bentonite-based fluid showed that 0.019 wt% (0.1 g) of NPs reduced the coefficient of friction by 47%, and 0.0095 wt% (0.05 g) of NPs reduced the fluid loss by 20%. Moreover, for KCl-based fluids, 0.019 wt% (0.1 g) of additive reduced the coefficient of friction by 45%, while higher concentration of 0.038 wt% (0.2 g) of NPs shows 14% reduction in the filtrate loss. Microscale analysis shows that presence of NPs in the cake structure produces a more compact and less porous structure. This study indicates that very small concentration of NPs can provide better performance for the drilling fluids. Additionally, results from this work indicate the ability of NPs to fine-tune the properties of drilling fluids.

H2S Scavenging Capacity and Rheological Properties of Water-Based Drilling Muds

Drilling hydrocarbon formations where hydrogen sulfide (H₂S) is present could lead to the carryover of H₂S with the drilling mud (i.e., drilling fluid) to the surface, exposing working personnel to this lethal gas. Additionally, H₂S is very corrosive, causing severe corrosion of metal parts of the drilling equipment, which in turn results in serious operational problems. The addition of an effective H₂S scavenger(s) in the drilling mud formulations will overcome these health, safety, and operational issues. In this work, zinc oxide (ZnO), which is a common H₂S scavenger, has been incorporated into water-based drilling mud. The H₂S scavenging performance of this ZnO-containing drilling mud has been assessed. Additionally, drilling mud formulations containing either copper nitrate (Cu(NO₃)₂·3H₂O) or potassium permanganate (KMnO₄) have been prepared, and their H₂S scavenging performances have been studied and compared to that of the ZnO-containing drilling mud. It has been observed that the scavenging performance (in terms of the H₂S amounts scavenged up to the breakthrough time and at the saturation condition) of the ZnO-containing drilling mud is very poor compared to those of the copper nitrate-containing and KMnO₄-containing drilling muds. For instance, the amounts of H₂S scavenged up to the breakthrough time by ZnO-containing, copper nitrate-containing, and KMnO₄-containing drilling muds were 5.5, 15.8, and 125.3 mg/g, respectively. Furthermore, the amounts of H₂S scavenged at the saturation condition by these drilling muds were, respectively, 35.1, 146.8, and 307.5 mg/g, demonstrating the superiority of the KMnO₄-containing drilling mud. Besides its attractive H₂S scavenging performance, the KMnO₄-containing drilling mud possessed more favorable rheological properties [i.e., plastic viscosity (PV), yield point (YP), carrying capacity of the drill cuttings, and gelling characteristics] relative to the base and the ZnO-containing and copper nitrate-containing drilling muds. The addition of KMnO₄ to the base drilling mud increased its apparent viscosity, PV, and YP by 20, 33, and 10%, respectively. Additionally, all tested drilling muds possessed acceptable fluid loss characteristics. To the best of our knowledge, there are so far no published studies concurrently tackling the H₂S scavenging (i.e., breakthrough time, breakthrough capacity, saturation time, saturation capacity, and scavenger utilization) and the rheological properties of water-based drilling muds, as demonstrated in the current study, highlighting the novelty of this work.

Rice husk and saw dust as filter loss control agents for water-based muds

When drilling with water based muds (WBM), significant fluid loss volumes from the mud into the formation can have adverse effects not just on the mud and its properties but also on the stability of the wellbore. Prevention of mud filter loss is one way of assessing the performance of a drilling mud. However, evaluation of the effectiveness or otherwise of a fluid loss control additive can be made by characterizing the mud cake formed. Interestingly, the mud cake characterization is one area that has been somewhat neglected in drilling fluid formulation with agro waste materials. Two cellulosic materials - rice husk and saw dust were chosen for the experimental study. The specie of the rice husk used was the African rice (Oryza glaberrima) while the dust from the saw milling of Oxystigma manni was utilized for this study. To ensure result acceptability, the rice husk and saw dust were ground and the resulting products were sieved to 1.25 × 10⁻⁴ m. The filtration characteristics of the formulated mud samples were tested using the American Petroleum Institute (API) filter press and in accordance to the API recommended practice for field testing WBMs. From the filter loss tests, it was observed that the ground rice husk prevented filter loss by an average of 77% compared to ground saw dust filtration control of 63%. In addition, it was observed that at higher concentrations, ground saw dust and rice husk prevented fluid loss to the minimum acceptable API standard. For the filter cake thickness measured in millimetres, ground rice husk exhibited thicker mud cakes when compared with the saw dust by an average amount of 14%. For the mud cake characteristics, the rice husk mud exhibited smooth and slippery cakes while the saw dust mud exhibited rough texture, sticky and firm cakes.