Synthetic-based Drilling Fluids Research Articles

Development of Multiple Crosslinked Polymers and Its Application in Synthetic-Based Drilling Fluids.

This study addresses the performance challenges of Synthetic-Based Drilling Fluids (SBDF) in deep wells and high-temperature environments by engineering a novel multiple hydrogen-bonded crosslinked polymer, MBAH/nano-SiO2. Synthesized using methyl methacrylate (MMA), butyl methacrylate (BMA), acrylic acid (AA), N-hydroxyethyl acrylamide (HEAA), and nano-silica (nano-SiO2), the polymer improved crosslinking density, thermal properties, particle size distribution, and colloidal stability. The development of a 'weak gel' structure in W/O emulsions improved rheology and electrical stability (ES), with ES values reaching up to 775 V after aging at 180 °C. Moreover, the polymer's amphiphilic structure and the synergistic effect of nano-SiO2 increased emulsion film thickness and strength, further augmenting stability. The high-temperature and high-pressure filtration loss of SBDF was considerably reduced to 7.6 mL, benefiting well wall stability and reservoir damage control. This study provides crucial insights into optimizing multiple hydrogen-bonded crosslinked strategies and polymers in SBDF applications.

Evaluation of low-gravity-solids sedimentation in non-Newtonian synthetic-based drilling fluids monitored by gamma-ray attenuation technique

ABSTRACT Drilling fluids are used in the process of drilling wellbores. They are formulated by a combination of solubles and suspended solids. During drilling, cuttings of rock formation may get in the mix. Some of them are too small and light to be removed from the fluids. They are called low-gravity solids (LGS). In no drilling situations, both solids may settle due to gravity. This project aimed to characterize the physical and rheological properties of synthetic-based drilling fluids and monitor the distribution of solids concentration in batch gravity settling experiments. The interplay of solid content and mud rheology was evaluated by pycnometry, retort, and rheological analysis. The Gamma-ray Attenuation Technique was applied to monitor the solid concentration along the test tube as a function of time. We analyzed two similar muds that slightly differed by the presence LGS The fluids presented non-Newtonian behavior, clear separation of solids in two phases and apparent viscosity changes. After 90 days, the clarified liquid region was formed between 16 and 22 cm from the bottom of the tube. This region took shape between 7 to 80 days, and the maximum solid concentration was approximately 9%. Finally, the LGS increased the fluid resistance of settling.

Dimer fatty acid and fatty amide effects on the properties of synthetic-based drilling fluids

This paper mainly deals with the analysis of chemical modification on a dimer of fat acid to evaluate the effect on synthetic drilling fluids. The performance of drilling fluids in the deepwater fields is negatively impacted by the elevation of rheological parameters. A required property of the drilling fluid is a minimal sensitivity of the rheological properties with respect to temperature, leading to a flat-rheology system. A proposed fatty amide was synthesized via condensation reaction between saturated dimer fatty acid and diethanolamine. In this reaction, it was used N,N′-dicyclohexylcarbodiimide as coupling agent and 4-dimethylaminopyridine as catalyst. The synthesized material was characterized by FTIR, 13C NMR, solubility tests and surface tension. Next, the precursor dimer fatty acid and the synthesized fatty amide were initially applied on a visual stability test in invert emulsion systems before application in synthetic drilling fluids. Spectroscopic analyses confirmed that fatty amide was successfully synthesized. Surface tension measurements showed that both dimer fatty acid and the fatty amide amide have not surfactant properties. However, when both products were applied in synthetic drilling fluids, electrical stability and HPHT filtration tests proved the ability to stabilize emulsion systems, probably, as network agents. In addition, the drilling fluids containing dimer fatty acid and fatty amide presented minimal viscosity sensitivity in the temperature range of 4–49 °C, at ambient pressure and 344 bar, leading to flat-rheology synthetic drilling fluids.

Microbial activity evaluation and aerobic transformation of deep water offshore synthetic drilling fluids in soil: A case study of ternary mixture of synthetic ethyl esters of plants oil (Seep mixture) synthetic drilling fluid in agbami (Niger delta) deep water field

Approval for offshore discharge of cuttings drilled with synthetic-based drilling Fluids (SBFs) by environmental regulatory and protection agencies usually require detailed laboratory biodegradation analysis of the base fluid chemicals among others. This concept of using biodegradation test as an environmental fluid-compliance criterion is that a fluid that degrades readily in the laboratory will not persist for an extensive period of time in the offshore environment.Hence, this research focuses on microbial activity measurement and aerobic biodegradation of a newly developed synthetic ester fluid named “ternary mixture of synthetic ethyl esters of plants oil (SEEPmixture)” and its’ comparison with already existing synthetic deep water fluids (SHBF and SEBF) in Agbami deep water field. The chemical composition and components of each drilling fluid sample was analyzed by a GC system combined with a high resolution accurate mass (HRAM) spectrometer while a Fourier transform infra-red (FTIR) spectroscopy was used for functional group identification.The microbial activity of each soil sample that was contaminated with different base oils (drilling fluids) and that of the uncontaminated soil sample (control) was determined by trapping the carbon IV Oxide (CO2) evolved from each soil sample with a strong alkali solution of barium hydroxide (Ba(OH)2) as the microbial biomass actively decompose soil organic matter. The degradation of the drilling fluid chemicals was monitored under aerobic conditions.The soil contaminated with SEBF fluid chemical experienced a low microbial activity due to its low respiration (low amount of evolved carbon IV oxide per mg of soil) but a more pronounced adverse effect on microbial activity was experienced by soil contaminated with SHBF chemical. While microbial activities were not impaired with the SEEP mixture fluid chemical presence in the soil. Meanwhile, in regards to soil aerobic transformation, the SEEP mixture fluid took the shortest time of 13.6 days for it to decompose to half of its original concentration (5mg/kgsoil) from an initial concentration of 10 mg/kg soil. This implies that the fluid sample is readily and inherently biodegradable in soil. Whereas, the SHBF fluid sample required about 34.50 days for it to decompose to half of its original concentration. This indicates its non-readily biodegradable nature in soil. The half-life of the SEBF was 25 days and thus not readily biodegradable.

Dynamic thermal aging of water-based drilling fluids with different types of low-rank coals as environmental friendly shear thinning additives

This paper focuses on the development of a drilling fluid system that satisfies both environmental and technical requirements, acting as an environmentally appropriate alternative to oil or synthetic-based drilling fluids. The effectiveness of two types of low-rank coals (leonardite & lignite) as shear-thinning additives on the rheological behaviour and filtration control in drilling fluids after dynamic thermal aging is investigated. The most suitable model that best describes their rheology is the Herschel-Buckley model over the entire range of shear rates and all temperature levels. Dynamic thermal aging influences the yield stress at zero shear rates, the consistency index, the flow behaviour index of the Herschel-Buckley model as well as the yield point and plastic viscosity of the Bingham-Plastic model. Despite their geochemical differences, the addition of both low-rank coals in the drilling fluids improves the yield stress and yield point build-up with temperature increase and maintains them within acceptable values compared with coal-free drilling fluids. The highest aging temperature under dynamic conditions deteriorates significantly the rheological and filtration control parameters. For the specific concentration of additives and dynamic thermal aging, the temperature of 177 °C appears to be an upper thermal bound which the drilling fluids lose their design purpose. It is also demonstrated that considerable energy is required to change both the plastic viscosity and the yield point of the proposed drilling fluids with both low rank coals showing their effectiveness as shear thinning agents to maintain the desired low shear strength and yield point after dynamic thermal aging.

Deepwater Oil-Based Drilling Fluid Systembased on Grey Wolf Optimized BP neural network

In this paper, a BP neural network model with 5-9-6 structure is constructed according to various fault gases and different fault types ofWater-based drilling fluid and synthetic-based drilling fluid. While there are few studies relating to oil-based drilling fluid, which is attributed to the potential toxicity of conventional oil-based drilling fluid to the marine environment. However, oil-based drilling fluid is excellent in protecting the borehole stability. To this end, an environmentally friendly deepwater oil-based drilling fluid was developed based on the traditional oil-based drilling fluid. With the advantages such as good borehole stability and good wettability, this drilling fluid will not pollute the marine environment, is resistant to high temperature, and protects hydrocarbon reservoir, which is of great significance for rational exploration and development of deep-sea resources.

An experimental study of gas solubility in glycerin based drilling fluid applied to well control

The drilling fluid is the primary barrier element against a kick. In the path of drilling fluids evolution, synthetic-based drilling fluid (SBDF) is commonly used on offshore rigs due to its benefits to the high level of drilling complexity, especially at deep and ultra-deep-water scenarios. However, when formation gas dissolves in the mud due to high pressure and high temperature, the complexity of kick detection increases significantly. Furthermore, environmental concerns raised a red flag on SBDF usage due to potential impacts on the marine environment, with most governmental agencies around the world passing very strict regulations. Considering both aspects - safety, and environmental concerns - glycerin emerges as a potential candidate to perform a key role as a base drilling fluid (GBDF). At first, a GBDF has the potential to behave as an SBDF due to its benefits, such as lubricity and shale stabilization, and, at the same time, it has the same characteristics of water-based drilling fluid (WBDF) with very low methane solubility, the major component of natural gas. Additionally, GBDF is considered to be more environmentally friendly than SBDF. In this work, we first analyzed the PVT properties and rheology of three different molar composition glycerin-based drilling fluids: 100% glycerin, 50-50% glycerin/brine, and 40–60% glycerin/brine. Then, we performed the PVT properties analysis of methane (10–50% molar mass) mixed with each of these GBDF mentioned. In a systematic constant composition expansion through a visual high-resolution PVT cell under temperature and pressure range conditions of 20–80 °C and 0–55 MPa, respectively, and rheology characterization. The GBDF exhibited interesting results for density and rheology parameters similar to an SDBF and no methane solubility. Finally, mathematical correlations are proposed and applied to illustrate a pit-gain calculation comparing to an n-paraffin-based drilling fluid. • No solubilization can be considered between methane and glycerin drilling fluid under HPHT conditions studied. • Glycerin drilling fluid potential to behave as a synthetic drilling fluid and as water drilling fluid at the same time. • Crude glycerin drilling fluid showed a stable rheological trend regardless of the increase in temperature and shear rate. • The desire fluid density can be achieved by adding water in glycerin solution reducing the need for fluid thickening.

Microwave remediation of oil-contaminated drill cuttings – A review

In the oil drilling process, drill cuttings are loaded to the surface by the drilling fluid. When using synthetic-based drilling fluids, drill cuttings should be subjected to a separation process for later disposal of cuttings and reuse of drilling fluid. Several techniques have been used to adapt the drilling waste disposal to the environmental legislation, including microwave thermal desorption technology. This review presents the main studies on the microwave drying remediation of drill cuttings contaminated with synthetic-based drilling fluids, with emphasis on the advantages and disadvantages of the technologies used, making a comparative analysis of the methods. Although batch remediation prototypes allow reaching low residual oil levels, it presents low processing rates and high specific energies. Alternative batch decontamination processes can be used to increase the efficiency of oil removal, such as changing the thickness and the mechanical stirring of the bed, injection of carrier gas, reduction of heating rate, etc. These prototypes are also capable of remediation of reservoir cuttings, but with higher energy costs. Continuous industrial scale prototypes also achieve low oil residual levels (<0.1%), with relatively high flow rates (100–750 kg/h) and lower energy costs, and are effective to treat both the conventional and pre-salt drill cuttings. However, despite their great commercialization potential, some adjustments are required for operation with diluted slurry and a more effective temperature control to prevent the chemical changes in the organic phase of the drilling fluids.

Application of silica (SiO2) nanofluid and Gemini surfactants to improve the viscous behavior and surface tension of water-based drilling fluids

Further studies into drilling fluids especially to reduce the use of oil and synthetic-based drilling fluids are ever-growing due to their contributions to environmental pollution. This study, therefore, attempts to evaluate the thermal, viscosity, surface tension, and filtration loss properties of water-based drilling fluids (WBDFs) upon the addition of Gemini surfactant-silica nanofluid. This surfactant-nanofluid was formed by dissolving silica nanofluid in the surfactant solution, and ultra-sonication was used to attain homogeneity. Characterization of the Gemini surfactant-silica (SiO2) nanofluid was done by Fourier Transform Infrared Spectroscopy (FTIR). The viscosity, surface tension, and filtration loss properties were studied using the rheometer, tensiometer, and low-pressure, low-temperature (LPLT) filter press respectively. The experimental results showed that Gemini surfactants contributed to the highest increase in drilling fluid viscosity compared to a conventional surfactant. Also, when combined with silica-nanoparticles showed better thermal stability with an 11% average change in viscosity with increasing temperature and a decrease in surface tension and filtration loss both showing a 17% and 12% decrease respectively.

Improving the rheological properties of alkaline-activated geopolymers using water-free fluids

Geopolymer systems are quite successfully used in such operations as industrial and civil construction, production of fire - resistant concrete, isolation and disposal of radioactive waste, etc. The oil and gas industry was no exception. They are one of the most promising alternatives to Portland cement in insulation operations. They allow achieving sufficiently high performances of well construction strength, corrosion resistance, and in some compositions these parameters significantly exceed those of Portland cement. In recent years, a significant amount of research has been carried out aimed at the development of geo polymer compositions for cementing oil and gas wells, which showed that these systems have strength characteristics comparable to Portland cement, low permeability, resistance to drilling mud and reservoir conditions, and the ability to self-repair. However, despite all the advantages of Geo polymer systems, their most significant disadvantage is poor regulation of rheological properties. Geo polymers (GP) with low ash content do not provide the proper rheological characteristics for the use in insulation operations. Low values of pumpability of solutions are still a serious restriction for wide practical implementation. The use of geopolymer solutions with the correct selection of the compositional composition capable of demonstrating significant improvements in strength and rheological parameters as a result of mixing with anhydrous drilling fluids is a very promising solution to this problem. The paper presents the results of research on the additives of non-aqueous fluids such as oil- based and synthetic-based drilling fluids and inverted emulsion drilling fluids on rheology of geo polymers. The obtained results allow stating that the rheological parameters of geo polymer compositions improve up to comparable values with Portland cement, which considerably extends the range of application of these solutions to use in operations of primary, squeeze cementing and well workover.

Rheological investigation of synthetic-based drilling fluid containing non-ionic surfactant pentaerythritol ester using full factorial design

Non-ionic surfactant pentaerythritol ester (PE ester) can be used as a lubricant and chemical thinner in flocculated synthetic-based mud (SBM). However, its adsorption on surfaces and at oil-water interfaces may interfere with anionic secondary emulsifier and organoclay additives in the mud. The interactions between these additives may significantly affect the viscosity of SBM emulsions. Therefore, in this study, we systematically developed SBM formulations containing a non-ionic surfactant PE ester and evaluated the interactions between the surfactant, secondary emulsifier, and organoclay that influence the rheology of SBM using a full factorial design. Three rheological properties were chosen as responses: plastic viscosity (PV) and yield point (YP), and YP/PV ratio. Factorial analysis of the interaction between the secondary emulsifier and PE ester showed that the interactions caused significant effects on PV, YP, and YP/PV ratio. These multiple responses were optimized using the desirability function, and the optimum formulation was at concentrations of 1.0 lb/bbl, 6.2 lb/bbl, and 1.0% for secondary emulsifier, organoclay, and PE ester, respectively. A quantitative relationship between the various factors and responses was established, allowing a prediction of desirable rheological properties for drilling operations.

Performance evaluation of esters and graphene nanoparticles as an additives on the rheological and lubrication properties of water-based drilling mud

In the practice of drilling horizontal, directional, and unstable well profiles, the friction produced by bit balling, wellbore instability, cavings, and dog-legs resulted in excessive torque and drag. The friction along with high torque and drag, which results from the drill string, casing, and wellbore contact, leads to pipe stucks, overpulls during tripping-outs, and even closure of the oil and gas well. Heat generated from metal contact between casing and drill string is the cause of wear of drill string and casing. Oil-based drilling fluids are identified to produce minimum friction and torque than that of water-based drilling fluid/mud (WBM). However, the use of oil-based drilling fluids is becoming obsolete due to stringent environmental regulations. Therefore, it is critical to identify and design a water-based drilling mud with lubricant additives that are environmentally friendly, cost-effective, and give better lubrication similar to oil-based and synthetic-based drilling fluid. The objective of this study is to investigate the effect of two additives PC60 (the product of the reaction of glycerol ​+ ​tall oil fatty acid) and graphene nanoparticles on the rheological and lubrication properties of water-based drilling fluid. All together total 14 drilling fluid samples have been prepared for the detailed analysis. Extensive experimental work has been done to study the effect of lubricant additives (PC60 and graphene nanoparticles) on the rheology and lubrication of various WBMs with different additive concentrations (1, 2, and 3% by volume) at 30, 60, and 90 ​°C. All samples were investigated for their rheology, viscoelastic behavior, and lubrication properties before and after hot rolling. The experimental data generated in this work have been successfully utilized to find various fitting parameter for the Bingham plastic rheological model, followed by a discussion on foaming tendency of the samples and effect of pH on the rheological stability of drilling fluid. Subsequently, a relationship between the coefficient of friction (in the presence of different lubricant additives in the mud) and rheological properties (plastic viscosity and yield point) of different drilling fluid samples have been proposed. • Rheological/lubrication properties of water-based drilling muds (WBMs) investigated. • The effect of two additives ester and graphene nanoparticles on WBM studied. • Ester-based WBMs shown better rheological performance/stability after hot rolling. • A relationship between coefficient of friction and rheological properties proposed. • Ester-based WBMs exhibit more foaming tendency than nano-graphene-based WBMs.

Synthesis of decyl methyl carbonate and a comparative assessment of its performance as the continuous phase of synthetic-based drilling fluids

Ester-based drilling fluids have been explored as an alternative to the mineral oil and diesel-based fluids for their low toxicity and high biodegradability. In this work, decyl methyl carbonate (DeMeC) was synthesized and assessed as a novel continuous phase for synthetic-based drilling fluids (SBF), since it is equally biodegradable, presents higher chemical stability and elastomer compatibility when compared to fatty ester bases. Babassu oil methyl esters (BME) were synthesized and tested for comparison. Fourier transform infrared spectroscopy (FTIR), gas chromatography coupled to a mass spectrometer (GC/MS) or a flame ionization (GC/FID) detector, thermogravimetry (TG/DTG/DSC) and proton nuclear magnetic resonance (1H NMR) techniques were applied for characterizing the obtained products and confirmed the synthesis of DeMeC and BME. The low pour point of DeMeC and BME may allow the application to approach the blowout preventer region in ultra-deepwater drilling, while the low viscosity of both compounds make them suitable for drilling operations. In addition, the high flash point value for both bases is considered safe for its use, transportation and storage. The drilling fluid produced with DeMeC (DeMeC-DF) presented high efficiency, with satisfactory results of plastic viscosity, initial and 10-min gel strengths, yield point and filtrate, thus standing out as a real alternative for application in synthetic-based drilling fluids.

Study on a New Environmentally Friendly Synthetic Fluid for Preparing Synthetic-Based Drilling Fluid

In view of the pollution problems related to using oil-based drilling fluids, we prepared a new environmentally friendly synthetic fluid, namely, NSF, for use in synthetic-based drilling fluid instead. We used heavy hydrocarbons from Daqing as raw material in our preparation and employed few-steps refining techniques, such as hydrodesulfurization, hydrodearomatization, and hydrogenation. After the treatment, the sulfur and aromatic hydrocarbon contents in the NSF were <0.5 mg/L, meeting international environmental standards. NSF is composed mainly of C12-C22 hydrocarbons, and is characterized by low impurity content, small specific gravity, and easy degradation. In addition, the LC50 value is >1,000,000 mg/L water-soluble fraction; therefore, its toxicity is <10% of that of diesel in oil-based drilling fluid and, as the flash point of NSF is about 134°C, the related fire hazard is low. The synthetic-based drilling fluid with NSF has the advantage of causing no swelling damage to the reservoir, and saves the cost of drilling fluid because it doesn't need to deal with the environmental problems (the sulfur and aromatic hydrocarbon contents were <0.5 mg/L) and field problems caused by the reaction between drilling fluid and reservoir, and greatly increases the ROP through reducing the drill pipe sticking and with C12-C22 hydrocarbons in synthetic-based fluid, and safely uses, and has stable drilling fluid performances which are flash point (134°C) and low fire hazard. We have therefore achieved our aim of preparing a high-quality and non-toxic synthetic fluid, of which the aromatic hydrocarbon and sulfur contents meet international standards. Using this synthetic-based drilling fluid therefore facilitates environment protection drilling.

Adsorption of non-ionic surfactants on organoclays in drilling fluid investigated by molecular descriptors and Monte Carlo random walk simulations

Non-ionic surfactants have been used as a rheology control additive in drilling fluids to prevent flocculation of solids, such as organoclays, and maintain mud dispersion. Here, the fundamental phenomena involved in non-ionic surfactant adsorption on organoclays and how it affects the rheology of synthetic-based drilling fluids were elucidated by the analysis of molecular descriptors and Monte Carlo simulations. Using the Random Forests machine learning algorithm software, the non-ionic surfactant adsorption on organoclays was found to be affected mainly by the hydrophobicity and molecular shape of hydrophobic chains of non-ionic surfactants. Molecular descriptor calculations indicated that the hydrophobic interaction and van der Waals forces are dominant factors. Then, the Monte Carlo simulations provided the empirical effect of the non-ionic surfactant hydrophobic chains on their self-assembly to organoclays. Molecules with two chains were found to be easily adsorbed to the surface due to molecular size, while molecules with three and four chains occupy more sites and interact with each other more frequently, forming larger clusters. Consequently, non-ionic surfactants with more hydrophobic chains were predicted to improve rheology of drilling fluids and form stable mud emulsions. This approach is useful in predicting the effects of new additive in drilling fluid formulation.

Development of environment-friendly oil-in-water emulsion based drilling fluid for shale gas formation using sunflower oil

Mineral oils are frequently used for the making of synthetic-based drilling fluids. However, there are several downsides associated with these oils. These mineral oils are non-renewable, toxic in nature, non-biodegradable and prompting towards the incredible expense of waste treatment. In this research article, an anionic surfactant sodium methyl ester sulfonate (SMES) was synthesized using sunflower oil. SMES is then used to formulate environment-friendly oil-in-water emulsion-based drilling fluid. The synthesized surfactant is characterized by FT-IR, 1H-NMR and TGA analysis. The effect of xanthan gum (XG), bentonite, and sodium methyl ester sulfonate (SMES) on the rheology and filtration characteristics of developed emulsion based drilling fluid was analyzed thoroughly. The developed emulsion based drilling fluid had lower friction coefficient in case of oil concentration compared to SMES concentration. The zeta potential has been measured to check the emulsion stability and it has been attended that an increase in the concentration of SMES (0.3–0.7 wt/v %) and xanthan gum (0.2–0.6 wt/v %) has improved the stability of the emulsion. The contact angle and interfacial tension were analyzed and it was observed that interfacial tension was reduced from 102.5 to 25.35 mN/m and contact angle increased from 32.5° to 92.3°. The thermal stability of oil-in-water emulsion based drilling fluid was maintained up to 140 °C.

Screening and characterization of high performance synthetic-based drilling fluids degrading bacteria

In this paper, eight degrading bacteria using waste high performance synthetic-based fluids (WHPSF) as sole carbon source were isolated. Genetic analysis showed that these strains belonged to 8 species, and distributed in 3 genera. Of them, genus Bacillus was the predominated one with 6 strains. Based on the COD removal rate, 3 effective strains, i.e. SQ17, SQ8-1 and SQ6-1, were screened; and SQ6-1 had the highest COD degradation rate (40.26%). Growth characteristic analysis indicated that SQ8-1 and SQ6-1 could grow at initial pH value from 4.0 to 10.0, and grow at 10 °C to 40 °C. Moreover, these bacterial strains had strong ability to degrade WHPSF, and both the bacteria amount and COD removal rate increased along with treating time. The results suggested that these bacteria could degrade WHPSF properly, and had good application potential.

Development and Performance Evaluation of a Deep Water Synthetic Based Drilling Fluid System

With the enhancement of environmental protection awareness, the requirements on drilling fluid are increasingly strict, and the use of ordinary oil-based drilling fluid has been strictly restricted. In order to solve the environmental protection and oil-gas reservoir protection problems of offshore oil drilling, a new synthetic basic drilling fluid system is developed. The basic formula is as follows: a basic fluid (80% Linear a-olefin + 20% Simulated seawater) + 2.5% nano organobentonite + 3.5% emulsifier RHJ-5# + 2.5% fluid loss agent SDJ-1 + 1.5% CaO + the right amount of oil wetting barite to adjust the density, and a multifunctional oil and gas formation protective agent YRZ has been developed. The performance was evaluated using a high-low-high-temperature rheometer, a high-temperature and high-pressure demulsification voltage tester, and a high-temperature and high-pressure dynamic fluid loss meter. The results show that the developed synthetic based drilling fluid has good rheological property, demulsification voltage ≥ 500 V, temperature resistance up to 160°C, high temperature and high pressure filtration loss < 3.5 mL. After adding 2% - 5% YRZ into the basic formula of synthetic based drilling fluid, the permeability recovery value exceeds 90% and the reservoir protection effect is excellent. The new synthetic deepwater drilling fluid is expected to have a good application prospect in offshore deepwater drilling.

Rapid Crosslinking Polymer Provides an Additional Blowout-Preventer Barrier

SummaryThe industry maintains well control through proper well design and appropriate controls and barriers. This has made a hydrocarbon release from loss of well control a very–low–probability event. The current final barrier to maintain control is a valve system [blowout preventer (BOP)] located on top of wells, capable of isolating them by sealing around or shearing through obstructions that might be in the well (e.g., drillpipe and casing). Although the risk is low, there are still concerns regarding well control, especially for operations in sensitive environments. Adding an additional barrier could alleviate these concerns. We are currently evaluating a concept to respond to BOP seal failure by injecting a liquid monomer and a catalyst below a BOP leak point to rapidly form a polymer–plug seal.Mixtures of dicyclopentadiene (DCPD) and other monomers mixed with a ruthenium–based catalyst cause a rapid polymerization reaction that forms a stable solid. These reactions can occur under extreme temperatures and pressures and can withstand significant contamination from other fluids and solids.Laboratory studies showed that DCPD–based polymer plugs can withstand axial stress of 100 MPa (15,000 psi) without significant deformation, even at temperatures of 200°C and with 20 wt% synthetic–based–drilling–fluid contamination. Viscosity testing performed at 4°C showed that the liquid monomers and catalyst used to form polymers have viscosities low enough to allow rapid injection into a leaking BOP. Polymerization–reaction rates were not affected by the presence of high levels of drilling–fluid contamination or varying reaction temperatures. In all cases, reactions were rapid (less than 45 seconds) and resulted in the formation of solid polymers.

Optimization Work Flow Converts Power to Performance for GOM Drilling

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper OTC 29065, “Converting Power to Performance: Gulf of Mexico Examples of an Optimization Work Flow for Bit Selection, Drilling-System Design, and Operation,” by Mark W. Dykstra, SPE, Miguel A. Armenta, SPE, Fitzerald A. Mathew Ain, SPE, Omolara Adesokan, and Tess L. Schornick, Shell, and Ashabikash Roy Chowdhury, SPE, and Mark D. Allain, Baker Hughes, a GE company, prepared for the 2018 Offshore Technology Conference, Houston, 30 April–3 May. The paper has not been peer reviewed. Copyright 2018 Offshore Technology Conference. Reproduced by permission. Time spent on bottom drilling is only approximately 10% of the time consumed by drilling operations, but this still provides a significant opportunity for savings if it can be reduced. The goal of the work described in this paper was to decrease this percentage while drilling an exploratory well in the Gulf of Mexico. Significant results were achieved with the use of advanced hybrid polycrystalline-diamond-compact/tungsten-carbide-insert (PDC/TCI) bits. Introduction The focus well is in the Walker Ridge area approximately 150 nautical miles south of Port Fourchon, Louisiana. The rig floor to the zone of interest includes 6,500 ft of water, 1,200 ft of sediments, 12,250 ft of salt, and then deeper sediments. In the basic well design, a 38-in. conductor would be jetted to 200 ft below the mudline. The 26-in. section would be drilled through sediments and 2,000 ft of salt without risers using seawater and a 9.3-lbm/gal water-based pump-and-dump (PAD) drilling fluid, after which the 22-in. casing would be set. The 16½-in. section would be drilled through the bulk of the remaining salt with a riser in place using synthetic-based drilling fluid. The well would remain vertical until the kickoff point. After setting a 14-in. casing, the remaining hole sections would exit the salt and penetrate the deeper zones using synthetic-based drilling fluid. Design Phase: Offset Well Study The first step in the optimization process was to evaluate the drilling challenges that could be encountered in each hole section and identify potential performance limiters. The key lessons from the analysis of offset wells include the following: The shale/sand sequence above the salt would be soft and could be drilled as quickly as desired, though subject to wellbore stability and hole-cleaning limitations. The salt section would be very drillable, but mechanical specific energy (MSE) levels would be approximately 40 ksi. PDC bits would be very aggressive, so torque would be highly sensitive to weight on bit (WOB). Peak rate of penetration (ROP) in both salt and sediments would be directly proportional to the power provided to the bit. Torque variation could be as low as 10 to 20% for stiff drillstrings featuring 65/8-in. drillpipe using relatively high rotary speeds (e.g., 170 rev/min or greater). Bottomhole assembly (BHA) designs with a minimal tendency to hang up are desirable.