Modified Corn Starch as an Environmentally Friendly Rheology Enhancer and Fluid Loss Reducer for Water-Based Drilling Mud

Summary Drilling fluid rheology and fluid loss property are fundamental parameters that dictate the effectiveness and easiness of a drilling operation. Maintaining these parameters under high temperatures is technically challenging and has been an exciting research area for the drilling industry. Nonetheless, the use of drilling mud additives, particularly synthetic polymers, threaten ecological environments. Herein, modified corn starch (MCS) was synthesized, characterized, and investigated as an environmentally friendly rheology enhancer and filtration loss controlling agent for water-based mud (WBM) at high temperatures. The experimental results indicated that MCS exhibits better performance in improving rheological properties and fluid loss controlling ability for WBM than the commonly used mud additives. With the addition of an optimal concentration (0.3 wt%), MCS improved the rheology and fluid loss behavior of WBM formulation at harsh aging temperature (220°C) by practically 4 times and 1.7 times, respectively. The MCS was revealed to perform superbly over polyanionic cellulose (PAC) addition at all investigated temperatures. The better performance of the MCS was ascribed to the improved entanglements in the mud system owing to the additional hydroxyl (OH) groups. Besides, the Herschel-Bulkley model was found to be a constitutive model that described the rheological properties of the investigated muds satisfactorily. Moreover, the MCS was found to exhibit acceptable biodegradability properties.

Improving the rheological properties of water-based calcium bentonite drilling fluids using water-soluble polymers in high temperature applications

Most of bentonite used in modern drilling engineering is physically and chemically modified calcium bentonite. However, with the increase of drilling depth, the bottom hole temperature may reach 180 °C, thus a large amount of calcium bentonite used in the drilling fluid will be unstable. This paper covers three kinds of calcium bentonite with poor rheological properties at high temperature, such as apparent viscosity is greater than 45 mPa·s or less than 10 mPa·s, API filtration loss is greater than 25 mL/30 min, which are diluted type, shear thickening type and low-shear type, these defects will make the rheological properties of drilling fluid worse. The difference is attributed to bentonite mineral composition, such as montmorillonite with good hydration expansion performance. By adding three kinds of heat-resistant water-soluble copolymers Na-HPAN (hydrolyzed polyacrylonitrile sodium), PAS (polycarboxylate salt) and SMP (sulfomethyl phenolic resin), the rheological properties of calcium bentonite drilling fluids can be significantly improved. For example, the addition of 0.1 wt% Na-HPAN and 0.1 wt% PAS increased the apparent viscosity of the XZJ calcium bentonite suspension from 4.5 to 19.5 mPa·s at 180 °C, and the filtration loss also decreased from 20.2 to 17.8 mL.

Effect of silica nano particles on the rheological and HTHP filtration properties of environment friendly additive in water-based drilling fluid

Rheological and filtration properties of drilling fluid contribute a vital role in successful drilling operations. Rheological parameters such as apparent viscosity (AV), plastic viscosity (PV), yield point (YP) and gel strength of drilling fluids are very essential for hydraulic calculations and lifting of drill cuttings during the drilling operation. Control of filtration loss volume is also very important for cost effective and successful drilling operations. Therefore, the main goal of this research is to improve the rheological and filtration properties of Grewia Optiva fibre powder (GOFP) by using 30–50 nm size of silica nano particles (SNP) in water-based drilling fluid. The experimental outcomes revealed that after hot rolling of mud samples at 100 °C for 16 h, the low pressure-low temperature (LPLT) and high pressure-high temperature (HPHT) filtration loss of GOFP additives was improved, after the addition of SNP on it. The mixture of 5% GOFP + 4% SNP has reduced the LPLT and HPHT filtration loss of drilling fluid by 74.03 and 78.12%, respectively, as compared to base mud. Thus, it was concluded that after the addition of 0.4% SNP, the LPLT and HPHT filtration control ability of GOFP additive in WBM were increased by 17.6 and 15%, respectively. The rheological parameters such as AV, PV, YP and gelation of drilling fluids were also improved by the addition of GOFP + SNP mixture in the base mud. Therefore, the implementation of GOFP + SNP mixture in water-based mud showed auspicious results which reaffirm the feasibility of using them in the successful drilling operations.

A Zwitterionic Copolymer as Rheology Modifier and Fluid Loss Agents for Water-Based Drilling Fluids

To overcome the negative impact on the rheological and filtration loss properties of drilling fluids caused by elevated temperature and salts contamination, which are common in ultradeep or geothermal drilling operations, it is imperative to develop highly efficient additives used in the water-based drilling fluid. In this study, a zwitterionic copolymer P (AM/DMC/AMPS/DMAM, ADAD) was synthesized by using acrylamide (AM), cationic monomer methacrylatoethyl trimethyl ammonium chloride (DMC), anionic monomer 2-acrylamide-2-methyl propane sulfonic acid (AMPS), and N,N-dimethylacrylamide (DMAM) through free radical copolymerization. The copolymer was characterized by 1H Nuclear Magnetic Resonance (NMR), Fourier transform infrared spectroscopy (FTIR), elemental analysis, thermogravimetric analysis (TGA), and zeta potential. The rheological behavior, filtration properties, and the performance exposure to salt or calcium contamination in water-based drilling fluid were investigated. The bentonite/polymer suspension showed improved rheological and filtration properties even after aging at 160 °C or a high concentration of salt and calcium. The filtration loss can be greatly reduced by more than 50% (from 18 mL to 7 mL) by the inclusion of 2.0 wt% copolymer, while a slight increase in the filtrate loss was observed even when exposed to electrolyte contamination. Particle size distribution and zeta potential further validate the idea that zwitterionic copolymer can greatly improve the stability of base fluid suspension through positive group enhanced anchoring on the clay surface and repulsion force between negative particles. Moreover, this study can be directed towards the design and application of zwitterionic copolymer in a water-based drilling fluid.

Experimental Study on the Formation and Characteristics of Mud Filtration Cake in Large-Diameter Slurry Shield Tunneling

Multiple soil layers may be exposed simultaneously on the excavated surface of a large-diameter slurry shield. To study the formation and characteristics of mud filtration cake on the excavation surface during large-diameter slurry shield tunneling, penetration tests of mud slurries in different soils were carried out using a self-made device, and the microstructures of different mud filtration cakes were observed using scanning electron microscopy. The test results showed that there were three categories of filling forms for mud slurries permeating the soils: mud filtration cake, mud cake + permeation zone, and permeation zone; correspondingly, there were three types of filtration loss, which was mainly affected by the specific gravity of mud slurry. Finally, the porosity and the fractal dimension for the pore area of the mud filtration cake were calculated, and it is found that the fractal dimension of pore area is beneficial to classify the type of mud filtration cake.

Production and Characterization of an Eco-Friendly Oil Based Mud from Synthetic Bio-lubricant Derived from Chrysophyllum Albidum Seed Oil

Sequel to the environmental problems of the none biodegradable nature of the conventional oil-based drilling fluids, it is imperative and urgent for environmental sustainability and for the development of eco-friendly products, that use of petroleum diesel oil as the continuous phase of drilling mud warrant urgent reconsideration. Towards the search to provide a better alternative to petroleum diesel oil as a base oil for drilling mud, vegetable oil from the inedible seeds of the African star apple fruits, was examined In this study, an oil-based drilling mud (OBM) with biodegradable qualities for sustainable environmental applications was developed and characterized. The OBM was produced with chrysophyllum albidum (African star apple) oil methyl ester bio-lubricant to replace petroleum diesel as the continuous phase of the mud. The chrysophyllum albidum oil methyl ester was synthesized from fatty acid methyl ester obtained through transesterification process of none edible oils extracted from chrysophyllum albidum seeds. Tests of physiochemical and rheological properties were carried out on mud samples of chrysophyllum albidum oil biolube-based mud (CAOBBM) and petroleum diesel oil-based mud (PDOBM) to characterise the fluids for performance evaluation and environmental consequences. The findings indicated that CAOBBM was lower in density and less acidic than PDOBM, at barite content of 20 g. Also, CAOBBM had lower viscosity which implies less resistance to flow and lower pressure losses. The low oil to water ratio from the filtration loss test, revealed that CAOBBM is more viable to low fluid loss and consequently enhances wellbore stability and less oil retained on drilled cuttings. Similarly, toxicity test confirmed CAOBBM to be more appropriate and less detrimental to the environment compared to PDOBM. Summarily chrysophyllum albidum oil biolube based muds stands safer and more eco-friendly for a sustainable environment than petroleum diesel oil-based muds.

Shear Stress and Filtration Loss Properties Assessment of Nano-Silica Water-Based Drilling Fluid using Machine Learning Approaches

A complete overview of the rheology and filtration properties of drilling fluids are essential to ensure an efficient transport process with minimized fluid loss. Silica nanoparticle is an excellent additive for rheology and filtration properties enhancement. Existing correlations are not available for nano-SiO2-water-based drilling fluid that can extensively quantify the rheology or filtration loss of nanofluids. Thus, two data-driven machine learning approaches are proposed for prediction, i.e., artificial-neural-network (ANN) and least-square-support-vector-machine (LSSVM). Parameters involved for the prediction of shear stress are SiO2 concentration, temperature, and shear rate, whereas SiO2 nanoparticle concentration, temperature, and time are the inputs to simulate filtration volume. A feed-forward multilayer perceptron is constructed and optimized using the Levenberg-Marquardt learning algorithm. The parameters for the LSSVM are optimized using Couple Simulated Annealing (CSA). The performance of each model is evaluated based on several statistical parameters. The predicted results achieved R2(coefficient of determination) value higher than 0.99 and MAE (mean absolute error) and MAPE (mean absolute percentage error) value below 7% for both the models. The developed models are further validated with experimental data that reveals an excellent agreement between predicted and experimental data.

Review on Applications of Non-ionic and Anionic Surfactants in Water Based Drilling Fluids

In recent times, with the advent of exploSration activities in deeper hydrocarbon reserves, drilling of wells in HPHT conditions is one of the most studied field in the upstream oil and gas industry. Water-based fluids are the most common and frequently used drilling fluids oil and gas well construction. Although, water-based drilling fluids are environment friendly and relatively in-expensive, it is often associated with many problems when used in HPHT conditions. In order to overcome these problems in such viable conditions, modified surfactants are used with the mud to counteract the problems associated with it. This paper discusses the different applications of anionic and non-ionic surfactants in water-based drilling fluids both in laboratory and field scales. The paper also discusses the mechanisms of the surfactants and the effect on various mud properties to overcome hole problems like wellbore instability, rheology and filtration loss, foaming and flocculation of mud.

Preventing Drilling Fluid Induced Reservoir Formation Damage

During drilling of permeable reservoirs, drilling fluid may penetrate the formation and induce damage to the reservoir rock. Specifically, solids present in the drilling fluid may enter the formation and cause subsequent reduction in reservoir permeability in the area near the wellbore. When drilling with a water-based drilling fluid in a reservoir, various polymer-based additives are normally applied to reduce the filtration loss. These additives, such as Xanthan Gum, Poly Anionic Cellulose (PAC) and Starch may help in reducing losses to the formation in presence of small pore-throats and low differential pressures. If the pore throats exceed e.g. 20μm and differential pressures reach 500psi, these additives have little effect on reducing loss of drilling fluid to the formation and thereby little effect in preventing solids from entering the formation. Lost circulation is particularly challenging when losses occur in the reservoir section. This is because LCM treatment may create formation damages. Green et al. (SPE-185889) showed the nature of drilling fluid invasion, clean-up, and retention during reservoir formation drilling. They also showed the lack of direct relation between fluid loss and formation damage. In light of such ideas, a development of new Non-Invasive Fluid (NIF) additives was conducted. These additives were able to handle downhole pressure differences and create a preventative sealing of a permeable formation when applied into a solids-free drilling fluid. Ceramic discs of various permeability and mean pore-throat size were installed into a HTHP pressure cell. Drilling fluid was pumped through the cell and a filter cake was formed across the ceramic disc. A pressure of 500psi was applied and filtration loss was measured over a 30-minute period. Examples are herein presented showing how filter cake materials were applied into the drilling fluid and effectively sealing the permeable surface of the ceramic disc. Also, it will be shown how the filter cake was effectively removed from the discs using a breaker solution. Furthermore, a selection of experiments is presented, showing the possibility to heal lost circulation in permeable reservoirs without the presence of weighing materials, clays or drill-solids in the drilling fluid. A test was also conducted in such a way that the disc was fractured inside the test cell to investigate the impact on fluid loss.

The Utilization of Steelmaking Industrial Waste of Silicomanganese Fume as Filtration Loss Control in Drilling Fluid Application

Drilling fluid is considered the backbone of drilling operations in the oil and gas industry to unlock hydrocarbon from subterranean formations. Maintaining the drilling fluid properties, for example, flow properties such as rheology, plastic viscosity (PV), yield point (YP), gel strength (GS), and circulation loss, is the challenge for fluid/mud engineers to carry out successful drilling operations. A variety of chemicals have been added to improve the drilling fluid properties by introducing new chemicals(s) or optimizing the existing chemicals without affecting the other essential fluid properties. The present study for the first time employs the eco-innovation concept to explore the utilization of steelmaking industry waste, i.e. silicomanganese fume (SMF), as bridging material. The objective of this article is to design an eco-friendly framework that comprehensively explains and utilizes SMF as a bridging material in water-based fluid (WBF). The eco-innovation/eco-friendly framework includes the steps required for processing and understanding the new material and evaluating its effects on flow and the bridging properties of WBF. A scanning electron microscope (SEM), X-ray fluorescence (XRF), and particle size distribution (PSD) were used to understand the physiochemical properties of SMF. The flow properties were studied using a Fann rheometer before and after hot rolling at 120 °F. A high-pressure high-temperature (HPHT) filter press equipment was used to investigate the bridging capability of seepage losses following conditions of 190 °F and 300 psi differential pressure. Minimal cleaning and disintegration with a mortar and pestle are enough to prepare SMF to be incorporated in drilling fluid. The SEM and XRF results showed that SMF contains oxides of manganese, silicon, potassium, calcium, and magnesium, while the PSD revealed a natural bimodal distribution with an average grain size of D50 of around 29 microns. SMF showed a noticeable and measurable enhancement of flow properties and bridging capability in WBF. The SMF-based WBF showed improved rheological properties, plastic viscosity, and yield point compared to marble-based WBF. Adding SMF to WBF with and without marble showed a ten-fold superior plugging performance compared to marble-based WBF using 20-micron ceramic discs. The findings revealed the successful utilization of SMF in WBF by improving the rheology, plastic viscosity, yield point, and bridging capability.