Proper selection of drilling fluids plays a major role in determining the efficient completion of any drilling operation. With the increasing number of ultra-deep offshore wells being drilled and ever stringent environmental and safety regulations coming into effect, it becomes necessary to examine and understand the behavior of water based drilling fluids - which are cheaper and less polluting than their oil based counterpart - under extreme temperature and pressure conditions. In most of the existing literature, the testing procedure is simple - increase the temperature of the fluid in steps and record rheological properties at each step. A major drawback of this testing procedure is that it does not represent the continuous temperature change that occurs in a drilling fluid as it is circulated through the well bore. To have a better understanding of fluid behavior under such temperature variation, a continuous test procedure was devised in which the temperature of the drilling fluid was continuously increased to a pre-determined maximum value while monitoring one rheological parameter. The results of such tests may then be used to plan fluid treatment schedules. The experiments were conducted on a Chandler 7600 XHPHT viscometer and they seem to indicate specific temperature ranges above which the properties of the drilling fluid deteriorate. Different fluid compositions and drilling fluids in use in the field were tested and the results are discussed in detail.
In efforts to render the safest, fastest, and most cost efficient drilling program for a high temperature and high pressure (HT/HP) well the maximization of drilling operational efficiencies is key. Designing an adequate, HT/HP well specific, drilling fluid is of most importance and a technological challenge that can greatly affect the outcome of the overall operational efficiency. It is necessary to have a sound fundamental understanding of the behavior that water-based muds (WBM) exhibit when exposed to HT/HP conditions. Therefore, in order to adequately design and treat a WBM for a HT/HP well specific drilling program, it is essential that the mud be evaluated at HT/HP conditions. Currently, industry standard techniques used to evaluate WBM characteristics involve aging the fluid sample to a predetermined temperature, based on the anticipated bottom hole temperature (BHT), either statically or dynamically, for a predetermined length, then cooling and mixing the fluid and measuring its rheological properties at a significantly lower temperature. This, along with the fact that the fluid is not subjected to the anticipated bottom hole pressure (BHP) during or after the aging process, brings to question if the properties recorded are those that are truly experienced down-hole. Furthermore, these testing methods do not allow the user to effectively monitor the changes during the aging process. The research in this thesis is focused on evaluating a high performance WBM and the current test procedures used to evaluate their validity. Experimental static and dynamic aging tests were developed for comparative analysis as well to offer a more accurate and precise method to evaluate the effects experienced by WBM when subjected to HT/HP conditions. The experimental tests developed enable the user to monitor and evaluate, in real-time, the rheological changes that occur during the aging of a WBM while being subjected to true BHT and BHP. Detailed standard and experimental aging tests were conducted and suggest that the standard industry tests offer false rheological results with respect to true BHT and BHP. Furthermore, the experimental aging tests show that high pressure has a significant effect on the rheological properties of the WBM at elevated temperatures.
Designing a fit-for-purpose drilling fluid for high-pressure, high-temperature (HP/HT) operations is one of the greatest technological challenges facing the oil and gas industry today. Typically, a drilling fluid is subjected to increasing temperature and pressure with depth. While higher temperature decreases the drilling fluid0́9s viscosity due to thermal expansion, increased pressure increases its viscosity by compression. Under these extreme conditions, well control issues become more complicated and can easily be masked by methane and hydrogen sulfide solubility in oil-base fluids frequently used in HP/HT operations. Also current logging tools are at best not reliable since the anticipated bottom-hole temperature is often well above their operating limit. The Literature shows limited experimental data on drilling fluid properties beyond 350°F and 20,000 psig. The practice of extrapolation of fluid properties at some moderate level to extreme-HP/HT (XHP/HT) conditions is obsolete and could result in significant inaccuracies in hydraulics models. This research is focused on developing a methodology for testing drilling fluids at XHP/HT conditions using an automated viscometer. This state-of-the-art viscometer is capable of accurately measuring drilling fluids properties up to 600°F and 40,000 psig. A series of factorial experiments were performed on typical XHP/HT oil-based drilling fluids to investigate their change in rheology at these extreme conditions (200 to 600°F and 15,000 to 40,000 psig). Detailed statistical analyses involving: analysis of variance, hypothesis testing, evaluation of residuals and multiple linear regression are implemented using data from the laboratory experiments. I have developed the FluidStats program as an effective statistical tool for characterizing drilling fluids at XHP/HT conditions using factorial experiments. Results from the experiments show that different drilling fluids disintegrate at different temperatures depending on their composition (i.e. weighting agent, additives, oil/water ratio etc). The combined pressure-temperature effect on viscosity is complex. At high thresholds, the temperature effect is observed to be more dominant while the pressure effect is more pronounced at low temperatures. This research is vital because statistics show that well control incident rates for non- HP/HT wells range between 4% to 5% whereas for HP/HT wells, it is as high as 100% to 200%. It is pertinent to note that over 50% of the world0́9s proven oil and gas reserves lie below 14,000 ft subsea according to the Minerals Management Service (MMS). Thus drilling in HP/HT environment is fast becoming a common place especially in the Gulf of Mexico (GOM) where HP/HT resistant drilling fluids are increasingly being used to ensure safe and successful operations.
The book Solvents - Dilute, Dissolve, and Disperse - Insights on Green Solvents and Distillation takes the reader on a journey of chemistry and engineering toward sustainability. The book unravels the potential of green solvents, which are remarkably versatile, low-toxicity alternatives to traditional solvents that promise to reduce environmental impact. Latest research on supercritical fluids, ionic liquids, and deep eutectic solvents are carefully reviewed with emphasis on the numerous applications of green solvents. Additionally, as industrial demands evolve, the development of existing techniques is necessary. Distillation, the cornerstone of industrial separation, has been reimagined through groundbreaking approaches allowing for reduced operational costs and a diminished environmental footprint. The novel approaches in distillation offer advancement, allowing us to tackle the complexities of separating complex mixtures with unprecedented precision. Acknowledging these facts, this book covers new trends in this exciting research field of science and engineering. The book is an essential read for chemists, engineers, environmentalists, and anyone committed to fostering innovation for a greener tomorrow.
The petroleum industry in general has been dominated by engineers and production specialists. The upstream segment of the industry is dominated by drilling/completion engineers. Usually, neither of those disciplines have a great deal of training in the chemistry aspects of drilling and completing a well prior to its going on production. The chemistry of drilling fluids and completion fluids have a profound effect on the success of a well. For example, historically the drilling fluid costs to drill a well have averaged around 7% of the overall cost of the well, before completion. The successful delivery of up to 100% of that wellbore, in many cases may be attributable to the fluid used. Considered the "bible" of the industry, Composition and Properties of Drilling and Completion Fluids, first written by Walter Rogers in 1948, and updated on a regular basis thereafter, is a key tool to achieving successful delivery of the wellbore. In its Sixth Edition, Composition and Properties of Drilling and Completion Fluids has been updated and revised to incorporate new information on technology, economic, and political issues that have impacted the use of fluids to drill and complete oil and gas wells. With updated content on Completion Fluids and Reservoir Drilling Fluids, Health, Safety & Environment, Drilling Fluid Systems and Products, new fluid systems and additives from both chemical and engineering perspectives, Wellbore Stability, adding the new R&D on water-based muds, and with increased content on Equipment and Procedures for Evaluating Drilling Fluid Performance in light of the advent of digital technology and better manufacturing techniques, Composition and Properties of Drilling and Completion Fluids has been thoroughly updated to meet the drilling and completion engineer's needs. Explains a myriad of new products and fluid systems Cover the newest API/SI standards New R&D on water-based muds New emphases on Health, Safety & Environment New Chapter on waste management and disposal
This new book, Advances in Energy Materials and Environment Engineering, covers the timely issue of green applications of materials. It covers the diverse usages of carbon nanotubes for energy, for power, for the protection of the environment, and for new energy applications. The diverse topics in the volume include energy saving technologies, renewable energy, clean energy development, nuclear engineering and hydrogen energy, advanced power semiconductors, power systems and energy and much more. This timely book addresses the need of the hour and will prove to be valuable for environmentally conscious industry professionals, faculty and students, and researchers in materials science, engineering, and environment with interest in energy materials.
Recent studies highlighted the significant role of drilling fluid viscoelasticity in the assessment of frictional pressure loss, particle settling velocity, hole cleaning efficiency, and dynamic filtration loss control. Although the impact of drilling fluid viscoelasticity on the various functions of drilling fluids has been well recognized, the field implementation of these research findings have been hampered mainly because there has not been any standard field technique available for measuring the fluid viscoelastic properties. A comprehensive experimental investigation has, therefore, been conducted to develop a generalized model to determine the viscoelasticity of drilling fluids using standard field-testing equipment. The new field measurement-based methodology has then been used for developing new models and strategies that can be used for formulating optimum drilling fluid rheological properties for improving drilling fluid performance in two key applications areas; i-) Enhancing solids suspension ability, ii-) Reducing dynamic filtration loss. Ninety-three fluid formulations used in this study included field samples of oil-based drilling fluids as well as laboratory samples of water-based, invert emulsion and other oil-based fluids. Basic rheological characterizations of these fluids were done by using a funnel viscometer and a rotational viscometer. Elastic properties of the drilling fluids (quantified in terms of the energy required to cause an irreversible deformation in the fluid's structure called "energy dissipation") were obtained from oscillatory tests conducted by using a research grade rheometer with double gap concentric cylinder geometry. Using an empirical approach, a non-iterative model for quantifying drilling fluid elasticity was developed by correlating test results from a funnel iii viscometer and a rotational viscometer to energy required to cause an irreversible deformation of the fluid's elastic structure. Using the field measurement-based methodology for assessing the drilling fluid viscoelasticity , further experimental studies have been conducted to develop a generalized model for the field assessment of particle settling velocity in shear-thinning viscoelastic fluids by using the energy dissipation concept as an indicator of the fluid viscoelasticity. Ten different fluids were prepared in two groups based on their shear viscosity values. In each group, five fluids were having similar shear viscosity and variable elasticity values. Nineteen different spherical particles were used to conduct particle settling experiments with a density range from 2700 kg/m3 to 6000kg/m3 and a diameter range from 1mm to 4mm. Rheological characterizations of the fluids have been conducted by using funnel viscometer, API Rotational viscometer, controlled shear rate, and amplitude sweep test measurements. Fluid shear viscosity and elasticity have been identified as the most influential factors controlling filtration loss. However, past studies were mostly inconclusive regarding the individual effects of fluid shear viscosity vs elasticity, as it was very difficult to measure their effect independently. 24 water-based drilling fluids were prepared using various blends of three different molecular weight PHPA polymers. Two groups of fluids; one group having the same shear viscosity and variable elasticity and the other group having the same elasticity and variable shear viscosities, were developed. Additionally, 3 Xanthan Gum fluids were used as an example of iv visco-inelastic drill-in fluids commonly used for drilling long horizontal wellbore sections in the reservoir. Static filtration tests and core flooding experiments were conducted to measure the static filtration rate, pressure drop across the core at different flow rates, and formation damage induced by each fluid. By investigating the independent effects of viscoelasticity and shear viscosity on the fluid filtration loss characteristics, it was observed that: 1-) The static filtration rate can be more effectively controlled by altering fluid viscoelasticity as compared to the fluid shear viscosity. 2-) Both shear viscosity and viscoelasticity have a proportional relationship to the pressure drop associated with the core flow. However, the effect of viscoelasticity on the pressure drop is more pronounced. 3-) Increasing fluid viscoelasticity does not cause the formation damage as much as the shear viscosity. 4-)The viscoelasticity has been found to be the predominant rheological property that controls the solid-free drill-in fluids' filtration loss characteristics. The results have suggested that viscoelasticity can help develop non-invasive fluids by reducing static filtration rate, increasing pressure drop (effectively building internal cake), and minimizing formation damage.
