Drilling Fluid Technology Research Articles

Technology Focus: Drilling and Completion Fluids (November 2024)

This year’s primary selections for the Drilling and Completion Fluids Technology Focus reflect now-well-established industrywide emphases on machine learning (ML), automation, and the achievement of successful drilling of CO2 storage wells. Enhanced methods of modeling and monitoring allow time and cost savings while surpassing safety goals and furthering efforts to optimize CO2 storage. Paper OTC 35433 discusses a study centered on accurate gel-strength estimation. The authors leverage ML techniques, particularly the use of artificial neural networks, to develop predictive models for forecasting the gel strength of synthetic oil-based mud systems at both 10-second and 10-minute intervals, surpassing the precision and speed of techniques based on traditional rotational viscometers. In a similar vein, paper SPE 216322 seeks to bypass traditional manual methods of monitoring drilling fluids, its authors describing a novel online system that measures 10 key parameters continuously. They write that the system has been field-trialed across 200 wells with results that highlight the system’s reliability, with continuous operation for over 125 days. Finally, paper SPE 217711 involves evaluating the effects of an influx of CO2 into drilling fluids, a key task in the drilling of CO2 storage wells. Concentrating on oil-based drilling fluid, the presented study describes the development and integration of models for properties of drilling-fluid/CO2 mixtures into an existing software suite. Recommended-reading papers include an investigation of the use of microwave power in recovering oil from contaminated drill cuttings, reduction of the carbon footprint of drilling fluids, and sedimentation behavior of particles in fibrous sweep fluids. As always, the long-sighted ambition of such research, and the skill applied in its pursuit, reflects the commitment to excellence embodied by the authors of technical papers presented at SPE conferences. Recommended additional reading at OnePetro: www.onepetro.org. SPE 217140 Microwave-Assisted Technique for Oil Recovery From Oily Sludge Shale Drilled Cuttings by A. Agi, Universiti Malaysia Pahang, et al. OTC 34667 Successful Decarbonization of Drilling Fluids by Using Highly Efficient Technology and Reduced Chemical Usage, Logistics, and Casing Sections by Gerardo Jardinez, Pemex, et al. SPE 218631 Application of Machine-Learning Method for Modeling Settling Behavior of a Spherical Particle in Fibrous Drilling Fluids by R.M. Elgaddafi, Australian University, et al.

-Effects and mechanisms of acrylamide-based polymer containing N-vinylpyrrolidone on drilling fluids at high temperature

The exploration of ultra-deep oil and gas presents higher temperature resistance requirements for water-based drilling fluids. However, the lack of temperature resistance mechanism of drilling fluid polymers limits the development of key materials and drilling fluids. In this paper, by comparing the preparation of acrylamide polymers for drilling fluids, the influence of cyclic monomer N-vinylpyrrolidone (NVP) on the properties of polymers for drilling fluids was investigated, and the mechanism of NVP was deeply discussed. The results show that the NVP-containing copolymer PAAN has superior viscosity enhancement and filtration control in high-temperature drilling fluids. This is mainly due to the fact that PAAN has a more stable and complex polymer chain structure than PAA, the polymer that does not contain NVP, and its thermal stability is improved by 18.6 % up to 268°C. At the same time, NVP provides more adsorption spots, and the high-temperature clay adsorption capacity of PAAN in drilling fluids is increased by more than 66.9 % compared with that of PAA, which improves clay hydration and promotes clay dispersion, and ultimately reduces filtration of drilling fluids and stabilizes drilling fluids at high temperatures by more than 23.7 %. The introduction of NVP and the in-depth analysis of its action mechanism supplemented the anti-temperature mechanism of drilling fluid polymers, aiming to support the research and development of ultra-deep drilling fluid technology.

Improving Shale Stability through the Utilization of Graphene Nanopowder and Modified Polymer-Based Silica Nanocomposite in Water-Based Drilling Fluids

Shale formations present significant challenges to traditional drilling fluids due to fluid infiltration, cuttings dispersion, and shale swelling, which can destabilize the wellbore. While oil-based drilling fluids (OBM) effectively address these concerns about their environmental impact, their cost limits their widespread use. Recently, nanomaterials (NPs) have emerged as a promising approach in drilling fluid technology, offering an innovative solution to improve the efficiency of water-based drilling fluids (WBDFs) in shale operations. This study evaluates the potential of utilizing modified silica nanocomposite and graphene nanopowder to formulate a nanoparticle-enhanced water-based drilling fluid (NP-WBDF). The main objective is to investigate the impact of these nanoparticle additives on the flow characteristics, filtration efficiency, and inhibition properties of the NP-WBDF. In this research, a silica nanocomposite was successfully synthesized using emulsion polymerization and analyzed using FTIR, PSD, and TEM techniques. Results showed that the silica nanocomposite exhibited a unimodal particle size distribution ranging from 38 nm to 164 nm, with an average particle size of approximately 72 nm. Shale samples before and after interaction with the graphene nanopowder WBDF and the silica nanocomposite WBDF were analyzed using scanning electron microscopy (SEM). The NP-WBM underwent evaluation through API filtration tests (LTLP), high-temperature/high-pressure (HTHP) filtration tests, and rheological measurements conducted with a conventional viscometer. Experimental results showed that the silica nanocomposite and the graphene nanopowder effectively bridged and sealed shale pore throats, demonstrating superior inhibition performance compared to conventional WBDF. Post adsorption, the shale surface exhibited increased hydrophobicity, contributing to enhanced stability. Overall, the silica nanocomposite and the graphene nanopowder positively impacted rheological performance and provided favorable filtration control in water-based drilling fluids.

Research progress and development of deep and ultra-deep drilling fluid technology

The research progress of deep and ultra-deep drilling fluid technology systematically reviewed, the key problems existing are analyzed, and the future development direction is proposed. In view of the high temperature, high pressure and high stress, fracture development, wellbore instability, drilling fluid lost circulation and other problems faced in the process of deep and ultra-deep complex oil and gas drilling, scholars have developed deep and ultra-deep high-temperature and high-salt resistant water-based drilling fluid technology, high-temperature resistant oil-based/synthetic drilling fluid technology, drilling fluid technology for reservoir protection and drilling fluid lost circulation control technology. However, there are still some key problems such as insufficient resistance to high temperature, high pressure and high stress, wellbore instability and serious lost circulation. Therefore, the development direction of deep and ultra-deep drilling fluid technology in the future is proposed: (1) The technology of high-temperature and high-salt resistant water-based drilling fluid should focus on improving high temperature stability, improving rheological properties, strengthening filtration control and improving compatibility with formation. (2) The technology of oil-based/synthetic drilling fluid resistant to high temperature should further study in the aspects of easily degradable environmental protection additives with low toxicity such as high temperature stabilizer, rheological regulator and related supporting technologies. (3) The drilling fluid technology for reservoir protection should be devoted to the development of new high-performance additives and materials, and further improve the real-time monitoring technology by introducing advanced sensor networks and artificial intelligence algorithms. (4) The lost circulation control of drilling fluid should pay more attention to the integration and application of intelligent technology, the research and application of high-performance plugging materials, the exploration of diversified plugging techniques and methods, and the improvement of environmental protection and production safety awareness.

The Application of Well Control Technology in Drilling Process

Tarim Oilfield, as an important petroleum base in China, faces complex drilling challenges and risks. Well control technology plays a crucial role in this context, involving various aspects such as well control design, drilling fluid technology, and well control equipment. In the geologically complex environment of Tarim Oilfield, it is necessary to develop specific well control strategies tailored to the specific situation. The application of technologies such as drilling fluid technology, well control equipment, and real-time monitoring contributes to achieving safe and efficient drilling operations. This article evaluates the effectiveness of well control technology applications, combines practical case analyses, summarizes lessons learned, and provides guidance for future technological innovation and development directions. It also provides a theoretical foundation for well control in the exploration and development of Tarim Oilfield.

Improving the technology of drilling and well workover in conditions of unstable rocks

The exploration and extraction of hydrocarbons in regions characterized by unstable rock formations pose significant challenges to the oil and gas industry as increasing operational costs, safety hazards and environmental risks. This study focuses on advancing the technology of drilling and repairing wells in conditions where geological instability complicates traditional drilling processes, for example hole closure, collapse, fracturing etc. Moreover, it discusses all aspects of wellbore instability in drilling, from causes and symptoms to prevention and its impact. The mportance of ongoing research and development initiatives to advance drilling fluid technology suitable for unstable geological situations is also emphasized in the paper. In order to reduce the risk of borehole instability and maximize drilling efficiency, it investigates the formulation of high-performance drilling fluids with improved lubricity, filtration control, and shale inhibitory qualities. A frequent issue is lost circulation. Drilling fluid leaks into the nearby rock formations from the borehole cause this to happen. Numerous issues, like as decreased drilling efficiency, formation damage, and potentially environmental contamination, can result from lost circulation. The development of new technologies such as advancing drilling fluids, improving real-time monitoring are essential for improving the efficiency and safety of drilling and workover of wells in unstable rock formations.

Key Technology of 240°C High-Temperature Drilling Fluid

Hot dry rock (HDR) is a renewable green and clean energy source from the depths of the earth. It has the characteristics of high efficiency, environmental protection, safety, and stability, and is not restricted by seasons and climates. Difficulties in exploration and development include deep burial, formation fragmentation, abnormal pressure, high well temperature gradient, and high hole bottom temperature (usually >200°C), key technical issues such as sticking. This paper analyzes the difficulties of high-temperature resistant drilling fluid in dry hot rock: temperature resistance of treatment agents and systems, foaming, leakage, wellbore instability, and other problems. The optimization and experiment of treatment agents such as loss reducers, high-temperature protective agents, etc., and research on drilling fluid technology resistant to high temperature of 240°C in hot dry rock drilling has been carried out, through the optimization experiment of pulping materials and high temperature treatment agent. The main formula is: 3%-4% Sodium bentonite + 2%-3% HPS + 3%-4% SPNH + 2%-4% GJA + 3%-4% JSJ-1 + 0.5%-1.0% GGDP + 1% GBHJ. The drilling fluid formula has good rheology after hot rolling at 240°C, API filtrate loss<5ml, the viscosity recovery rate is over 90%. It provides effective technical support guarantee for promoting the exploration and development of hot dry rock resources in China.

Research and application of low oil-water ratio organoclay-free oil-based drilling fluid technology

This paper introduces the formation and application of a low oil-water ratio organoclay-free oil-based drilling fluid. Shale oil and gas are important alternative energy sources. Due to the extremely complex geological conditions, oil-based drilling fluid technology is commonly used to reduce complexity. Although some achievements have been made, there are still problems such as unstable wellbore, difficult rheological control, and high cost. A stable and low-viscosity water-in-oil emulsion system was successfully prepared by using optimized fatty acid imidazolines emulsifier and alkyl alcohol ether wetting agent, which enabled the oil-based drilling fluid to have a larger solid and water phase capacity. On this basis, a special poly-fatty acid amide rheological modifier was used to assist in the regulation of rheological parameters, resulting in a low-viscosity and high-shear structure of the oil-based drilling fluid. This effectively ensured the efficiency of cuttings carrying while reducing the adverse effects of viscosity on Equivalent Circulating Density(ECD). The low oil-water ratio oil-based drilling fluid technology has been applied in a shale gas drilling platform in southern Sichuan, China, which greatly reduces the cost of oil-based drilling fluid while ensuring drilling efficiency.

Research Progress of Elastomer Materials and Application of Elastomers in Drilling Fluid.

An elastomer is a material that undergoes large deformation under force and quickly recovers its approximate initial shape and size after withdrawing the external force. Furthermore, an elastomer can heal itself and increase volume when in contact with certain liquids. They have been widely used as sealing elements and packers in different oil drilling and development operations. With the development of drilling fluids, elastomer materials have also been gradually used as drilling fluid additives in drilling engineering practices. According to the material type classification, elastomer materials can be divided into polyurethane elastomer, epoxy elastomer, nanocomposite elastomer, rubber elastomer, etc. According to the function classification, elastomers can be divided into self-healing elastomers, expansion elastomers, etc. This paper systematically introduces the research progress of elastomer materials based on material type classification and functional classification. Combined with the requirements for drilling fluid additives in drilling fluid application practice, the application prospects of elastomer materials in drilling fluid plugging, fluid loss reduction, and lubrication are discussed. Oil-absorbing expansion and water-absorbing expansion elastomer materials, such as polyurethane, can be used as lost circulation materials, and enter the downhole to absorb water or absorb oil to expand, forming an overall high-strength elastomer to plug the leakage channel. When graphene/nano-composite material is used as a fluid loss additive, flexibility and elasticity facilitate the elastomer particles to enter the pores of the filter cake under the action of differential pressure, block a part of the larger pores, and thus, reduce the water loss, while it would not greatly change the rheology of drilling fluid. As a lubricating material, elastic graphite can form a protective film on the borehole wall, smooth the borehole wall, behaving like a scaly film, so that the sliding friction between the metal surface of the drill pipe and the casing becomes the sliding friction between the graphite flakes, thereby reducing the friction of the drilling fluid. Self-healing elastomers can be healed after being damaged by external forces, making drilling fluid technology more intelligent. The research and application of elastomer materials in the field of drilling fluid will promote the ability of drilling fluid to cope with complex formation changes, which is of great significance in the engineering development of oil and gas wells.

Research progress and development tendency of polymer drilling fluid technology for unconventional gas drilling

Unconventional gas includes tight sandstone gas, shale gas, coalbed methane, and natural gas hydrate. With huge reserves, unconventional gas has become the most important natural gas resource successor after the end of the “Easy Oil era.” The drilling fluid is an indispensable wellbore working fluid for unconventional gas drilling with multiple functions. The polymer drilling fluid (PDF) is the most common, longest developed, and most diverse drilling fluid type. With advantages of easily controlled rheology, convenient on-site performance maintenance, and specifically low cost and weak environment pollution, the PDF is gradually replacing the oil-based drilling fluid as the first choice for unconventional gas drilling. The invention of the non-disperse low-solid-content PDF in the 1960s shows that PDF technology has entered the stage of scientific development, and until now, its development has generally experienced five stages: beginning, developing, improving, re-developing, and re-improving. Dozens of polymer additives and PDF systems have been invented and applied, which have solved severe drilling problems, greatly improved drilling efficiency, and promoted exploration and development in difficult oil and gas resources. This paper first reviews the research progress of PDF technology according to the timeline by introducing the composition, feature, advantages, and disadvantages of some representative polymer additives and PDF systems, emphatically the function and mechanism of stabilizing wellbores, lubricating drilling tools, and protecting reservoirs of the biomimetic wellbore-strengthening PDF and amphiphobic high-efficiency PDF in unconventional gas drilling. Then, combining future global demands, especially China’s strategic needs of oil and gas exploration and development, the development tendency of PDF technology is critically illustrated by introducing several potential research directions including intelligent PDF, ecological PDF, and PDF for natural gas hydrate and deep layer gas resources.

Smart plugging and low-damage foam drilling fluid technology for CBM drilling

Once the drilling fluid filtrate invades along microfractures of coal reservoirs during the drilling process, it can cause notable wall instability. Foam spheres would infiltrate and move through the pores and into the fractures under drilling differential pressure between the wellbore and formation. As a result, microfoams deformed and the volume became larger to achieve plugging. In order to improve the foam foaming performance and stability during drilling, thereby enhancing the plugging effect, a new type of anionic Gemini surfactant, ZY-1, was designed and synthesised. Not only did ZY-1 reduce surface tension but also the half-life of foams produced was more than three times that of conventional foaming agents. Furthermore, contact angle recovery rate of cores and the desorption rate of drilling fluid reached 86% and 88.24%, respectively. And the plugging rate and gas permeability recovery value after pollution were both above 90% for the developed low-damage drilling fluid. [Received: October 24, 2021; Accepted: April 26, 2022]

Novel Water-Based Drilling and Completion Fluid Technology to Improve Wellbore Quality During Drilling and Protect Unconventional Reservoirs

The efficient exploration and development of unconventional oil and gas are critical for increasing the self-sufficiency of oil and gas supplies in China. However, such operations continue to face serious problems (e.g., borehole collapse, loss, and high friction), and associated formation damage can severely impact well completion rates, increase costs, and reduce efficiencies. Water-based drilling fluids possess certain advantages over oil-based drilling fluids and may offer lasting solutions to resolve the aforementioned issues. However, a significant breakthrough with this material has not yet been made, and major technical problems continue to hinder the economic and large-scale development of unconventional oil and gas. Here, the international frontier external method, which only improves drilling fluid inhibition and lubricity, is expanded into an internal-external technique that improves the overall wellbore quality during drilling. Bionic technologies are introduced into the chemical material synthesis process to imitate the activity of life. A novel drilling and completion fluid technique was developed to improve wellbore quality during drilling and safeguard formation integrity. Macroscopic and microscopic analyses indicated that in terms of wellbore stability, lubricity, and formation protection, this approach could outperform methods that use typical oil-based drilling fluids. The proposed method also achieves a classification upgrade from environmentally protective drilling fluid to an ecologically friendly drilling fluid. The developed technology was verified in more than 1000 unconventional oil and gas wells in China, and the results indicate significant alleviation of the formation damage attributed to borehole collapse, loss, and high friction. It has been recognized as an effective core technology for exploiting unconventional oil and gas resources. This study introduces a novel research direction for formation protection technology and demonstrates that observations and learning from the natural world can provide an inexhaustible source of ideas and inspire the creation of original materials, technologies, and theories for petroleum engineering.

Drilling fluid for stabilizing the wellbore in compound-salt formation based on multiple-synergism-method

The complex features of the compound-salt formation result in wellbore instability during drilling operations. The mechanism of wellbore instability in compound-salt formation is studied by the analysis of mineral compositions, microstructures, physical-chemical properties, and interface mechanical properties of compound salts from different areas. The results show that the existing micro-scale pores and fractures, creep and dissolution of salt, hydration of gypsum-mudstones are the key causes of wellbore instability in compound-salt formation. In order to stabilize the wellbore in compound-salt, we propose the drilling strategies based on the synergism of multiple methods of strengthening the wellbore by the sealing and consolidating effect of drilling fluid, inhibiting the dissolution of salt and the hydration of gypsum-mudstones, balancing the water activity between rocks and drilling fluid, providing effective stress to support the wellbore. Based on the effect of water activity on the shale hydration swelling and dispersion properties, the design basis of the safe window of water activity for drilling fluids is determined. According to the wellbore instability problems when drilling in compound-salt formations in M Oil Field in the Middle East, H-S Oil Field of Uzbekistan, and Xinjiang Uygur Autonomous Region of China, the drilling fluids are designed respectively based on the proposed wellbore stabilizing technology. The field applications show that the drilling fluid technology greatly improves the wellbore stability in compound salt formations and reduces downhole problems, thereby improving drilling efficiency.

Research status and development directions of intelligent drilling fluid technologies

By reviewing the current status of drilling fluid technologies with primary intelligence features at home and abroad, the development background and intelligent response mechanisms of drilling fluid technologies such as variable density, salt response, reversible emulsification, constant rheology, shape memory loss prevention and plugging, intelligent reservoir protection and in-situ rheology control are elaborated, current issues and future challenges are analyzed, and it is pointed out that intelligent material science, nanoscience and artificial intelligence theory are important methods for future research of intelligent drilling fluid technology of horizontal wells with more advanced intelligent features of “self-identification, self-tuning and self-adaptation”. Based on the aforementioned outline and integrated with the demands from the drilling fluid technology and intelligent drilling fluid theory, three development suggestions are put forward: (1) research and develop intelligent drilling fluids responding to variable formation pressure, variable formation lithology and fluid, variable reservoir characteristics, high temperature formation and complex ground environmental protection needs; (2) establish an expert system for intelligent drilling fluid design and management; and (3) establish a real-time intelligent check and maintenance processing network.

Effect and mechanism of microbial solid-free drilling fluid for borehole wall enhancement

Borehole wall instability in broken formations has long been a significant problem in drilling engineering. Microbe-induced calcium carbonate precipitation (MICP) technology offers a promising approach for solving this problem. This study combines microorganisms and drilling fluid technology for the first time to explore a new drilling fluid technology designed to address the instability of a broken-formation borehole wall. First, we selected a solid-free drilling fluid suitable for the growth of Bacillus pasteurii and formulated a microorganism-containing solid-free drilling fluid. We then conducted an orthogonal-design experiment to investigate the effectiveness of the drilling fluid in enhancing the borehole wall. Finally, we analyzed the borehole wall-enhancement mechanism of the drilling fluid using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results show that 0.4% sodium carboxymethyl cellulose (CMC) solid-free drilling fluid is suitable for the formulation of microorganism-containing solid-free drilling fluid and that it can cement gravel soil (simulating broken formations) into a whole. The amount of calcium produced in the sample reached 6.63 g, the unconfined compressive strength was 0.324 MPa, and the permeability coefficient was reduced to 0.202 cm/s. The forms of calcium carbonate crystals generated in the sample were vaterite and calcite, which filled the pores and played a cementing role, thereby increasing the strength of the sample and reducing its permeability. This study proposes new ideas for solving the problem of borehole wall instability in broken formation using drilling fluid techniques and thus has positive theoretical and practical significance.

Drilling Fluid Technology for the Third Interval of Sunan 23-113H2 Well

In the construction process of Sunan 23-113H2 well, there wasYanchang well, Liujiagou well and Shihezi well, when passing through the well, the mudstone collapse of the large slope section caused the difficulty of reaming off, after repeated reaming off, the wellbore still cannot be unblocked. Finally, the well structure was changed from the conventional Third Interval to the optimized Third Interval, and the technical casing is lowered to the depth of the inclined 45° well in the inclined shaft section. After the Third Interval, the mudstone of the large inclined section and the horizontal section collapsed, and the well leakage of the inclined well section and the horizontal section was still prominent. According to the construction situation of the Third Interval of the well, this paper optimizes the drilling fluid and refines the leak prevention and plugging measures through indoor experiments to provide technical support for safe drilling.

Improvement and application of drilling fluid technology for gas exploration wells in Yanchi block

Currently, the exploration and development scope of Changqing oilfield has gradually developed to edge blocks and deep systems, typically of Yanchi block. However, in the construction process, there are some problems such as poor well wall stability, frequent well leakage and prominent collapse contradiction, which seriously restricts the increase of drilling speed. In this paper, the measures such as well structure optimization, system formulation optimization, separate management of collapse and leakage, refined performance control, and pressure-bearing leakage plugging were taken by a combination with the construction situation in 2021 so as to improve drilling speed and reduce the complexity of downhole failures.

Smart plugging and low-damage foam drilling fluid technology for CBM drilling

Smart plugging and low-damage foam drilling fluid technology for CBM drilling

Analysis of Optimized Drilling Fluid Technology in Zhenye Well 3

Analysis of Optimized Drilling Fluid Technology in Zhenye Well 3

Drilling Fluid Technology for Horizontal Well in Ecuador Tambococha Oilfield

The Tambococha Block in Ecuador is an oil field with high porosity and high permeability reservoir characteristics, the lower formation is broken and micro-fractures are developed too. For this reason, utilizing Polyalcohol XCS-III and emulsified paraffin G325 as the main two agents, then optimizing other environmentally friendly agents, a strong plugging reservoir protection water-based drilling fluid is formed finally, which is suitable for the Tambococha oil field in Ecuador. The drilling fluid utilizes the synergistic plugging effect of emulsified droplets, cloud point effect, micron particles and rigid particles to reduce the oil-water interfacial tension and prevent the drilling fluid from entering the formation to finally achieve the purpose of anti-collapse plugging and reservoir protection. Laboratory experiments show that the drilling fluid has strong inhibitory properties, and the linear expansion rate of cuttings in it is reduced by 64.8% compared with that in clean water; the plugging performance is good, and its particle size distribution can fit the ideal filling curve better; the damage to reservoir is a little, with an average damage rate of 10.25% to the cores of the U layer of the Napo formation; the drilling fluid has good environmental performance, and the content of heavy metals meets the requirements of sewage discharge standards. The drilling fluid system has been successfully applied to 15 horizontal wells in the Tambochocha Oilfield. The main performance is with wellbore stability and smooth tripping. The average daily crude oil output of a single well neers 300 t, which is nearly 90% higher than that of offset wells, and the environmental indicators of drilling fluid and drilling cuttings meet the requirements of EPA1311 standards. The research results show that the water-based drilling fluid can meet the drilling safety and reservoir protection requirements of horizontal wells of the Tambococha oil field in Ecuador.