There are many factors affecting the filtration of drilling fluid into the drilled formation. The adverse impact of the filtration on the well productivity calls for concerted research effort towards ...developing promising solutions to minimize the volume of mud filtration and solid invasion. This study investigates the potentials of perlite as a filtration control agent under high pressure conditions. Perlite is an amorphous volcanic glass that occurs naturally and abundantly. Perlite was added to a high-density barite weighted drilling fluid at different concentrations. For the different perlite concentrations, fluid loss test was conducted to form filter cakes. NMR measurements were performed before and after fluid invasion and filter cake deposition to evaluate the amount and particle size distribution of the solids that invaded the core samples. The results showed that the drilling fluid formulations containing perlite controlled filtration loss and mud particles invasion better than standard barite weighted fluids.
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•Introduce “perlite” as new drilling fluid additive•Reduction in filter cake thickness by 30%, and filtration volume by 40% as consequence of perlite addition.•The cutting carrying capacity and sealing properties were improved due to the perlite addition.
In the field of petroleum engineering drilling, accurately and real-time determining the rheological properties of drilling fluids is crucial for controlling drilling operations. Traditional methods ...for measuring the rheological properties of drilling fluids are time-consuming and inefficient, hindering the optimization of real-time drilling fluid performance and impeding on-site decision-making for engineers. The development of artificial intelligence technology has improved the efficiency of measuring drilling fluid rheological properties. Predictive models for the rheological properties of water-based and all-oil-based drilling fluids have been established. However, these models perform well only on specific types of drilling fluids. Water-in-oil emulsion drilling fluids, while maintaining the advantages of all-oil-based drilling fluids, exhibit good environmental adaptability and are widely used in shale oil horizontal wells. This article comprehensively considers the impact of temperature and drilling fluid components (water % by vol, oil % by vol, solid % by vol) on drilling fluid performance. By using the GPR-Bagging improved ensemble algorithm, a predictive model for rheological parameters suitable for water-in-oil emulsion drilling fluids is established. Experimental results indicate that the new model accurately predicts the rheological properties of water-in-oil emulsion drilling fluids. The determination coefficients (R2) for the predictive models of apparent viscosity (AV)and plastic viscosity (PV) of drilling fluids both exceed 0.96, and the R2 for the behavior index (n) predictive model exceeds 0.90. When compared to existing mathematical and intelligent models, the new model demonstrates superior performance. The GPR-Bagging model enhances the measurement efficiency of rheological properties of water-in-oil emulsion drilling fluids, holding significant importance for promoting the automation of drilling fluid systems and drilling processes.
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•A GPR-Bagging algorithm established a rheological parameter prediction model for water-in-oil emulsion drilling fluids.•GPR-Bagging algorithm’s predictive performance surpasses existing mathematical and intelligent models.•GPR-Bagging enhances rheological property measurement efficiency, aiding on-site decision-making for engineers.•Rheological parameter prediction model for water-in-oil emulsion drilling fluids advances automation in drilling fluid systems and processes.
In this study, a new type of amphiphilic copolymer SPXFJ, with amide and sulfonate functional groups, was synthesized via the free radical polymerization method. And the chemical structure and ...properties of this new polymer were characterized by elemental analysis (EA), X‐ray photoelectron spectroscopy (XPS), intrinsic viscosity tests, and thermogravimetric analysis (TGA). The hydrophobic association and thermo‐thickening properties of SPXFJ copolymer were investigated through viscometer, contact angle tester, high‐resolution scanning electron microscope analysis, and X‐ray laser static scattering (XLSS) test. The test results indicated that SPXFJ copolymer showed superior amphiphilic properties, especially in the solution condition. Furthermore, a thermo‐associative behavior was found in the solution that aged at 180°C. Thus, SPXFJ‐based drilling fluid showed a higher temperature resistance. The test results, in both high‐temperature aging tests and high‐temperature high‐pressure (HTHP) downhole simulation tests, showed that the water‐based drilling fluid showed excellent anti‐sedimentation properties with the use of SPXFJ polymer and can be improved significantly, especially in the high‐pressure condition. The water‐based drilling fluid of 2.0 g/cm3 showed no sedimentation of barite powders at 180°C/100 MPa, of which the density deviation just reached approximately 0.06 g/cm3.
Amphiphilic copolymer SPXFJ with amide and sulfonate groups was synthesized and showed excellent thermo‐associative behavior in the water‐based drilling fluid, exhibiting remarkable anti‐sedimentation properties at 180°C/100 MPa.
Self-crosslinking soap-free latexes (PMS) were synthesized by semi-continuous polymerization from methyl methacrylate and styrene with N-(hydroxymethyl)acrylamide (NAM) as high-temperature ...self-crosslinker and 2-acrylamido-2-methyl-1-propanesulfonic acid as reactive emulsifier. All PMS latexes with varying NAM contents (0–7 wt%) processed high solid contents (~30%) and monodispersed nano-micro particle sizes (180–600 nm). With augment of NAM content, monomer conversion slightly decreased while particle size decreased and then gradually increased, accompanied with increase of coagulum content. The self-crosslinking behavior showed highly dependence on NAM content and temperature, and the self-crosslinked structures were confirmed by FT-IR, XPS, DSC and SEM. The self-crosslinking latexes effectively improved rheological and microporous filtration properties of bentonite-based drilling fluid. Owing to stronger interparticle interactions, the latexes exhibited better viscosity-increasing effect after thermal treatment and stronger fluid-loss-reducing ability at high temperature. The microporous plugging mechanism was revealed to be the combination of heat deforming and self-crosslinking film forming besides physical bridging and filling.
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•Series of self-crosslinking soap-free latexes were successfully synthesized.•Self-crosslinking behaviors were comprehensively investigated.•Self-crosslinking behaviors improved high-temperature performance of drilling fluid.•Microporous plugging mechanism was revealed and analyzed.
The object of this work was to improve the temperature and salt resistance of filtrate reducers used in solid‐free water‐based drilling fluids at 200°C. This copolymer (PAD) was obtained by reacting ...pentaerythritol triallyl ether (PTE) with acrylamide AM, N‐isopropyl acrylamide (N‐AM), methacrylic acid (MAA), and 2‐acrylamide‐2‐methylpropanesulfonic acid sodium (AMPS‐Na) in radical polymerization with potassium peroxydisulfate (KPS) and sodium bisulfite as initiators. The molar ratio of each monomer shown as follow: nAm:nN−Am:nMAA:nAmps: = 1:1.6:0.9:1.5. The functional groups of each monomer were revealed by Fourier transformation infrared. Moreover, 13C nuclear magnetic resonance confirmed the PAD was synthesized by addition polymerization through these monomers. Scanning electron microscopy showed that the surface of the filter cake was smooth and dense, indicating that PAD can effectively block small pores and thus reduce filter loss. The analysis suggested the PAD produced a “ball” structure at high temperature and salt which controlled the filtration of drilling fluid. The maximum temperature resistance boundary of PAD was 210°C. PAD maintained filtration performance in nearly saturated sodium chloride, 1.4 g/cm3 HCOOK and 1.37 g/cm3 HCOONa, at 210°C for 16 h.
(1) The polymer (PAD) was obtained by free radical polymerization as shown in the figure.
(2) The mechanism of polymer filtration reduction was shown in the figure. The extended polymer molecules constantly shrink and curl to form a certain “core‐shell” structure at high temperature and high salinity, thus controlling the filtration loss of the system.
In drilling operations, the fine drilled cutting are mixed with the drilling fluid. As a result, the properties of the drilling fluid, such as density and rheological properties, will change based on ...the cutting properties. Previous studies investigated the effect of rock type with different loadings on the drilling fluid properties. However, the effect of cutting’s mechanical properties variation was not addressed. In this paper, the effect of variation in cutting’s mechanical properties on the drilling fluid properties was investigated in sandstone reservoir. Particles of sandstone formation core samples with different compressive strength (UCS) and different Young’s modulus (
E
) were mixed, in different percentages, with the drilling fluid. The mechanical properties of the cuttings were determined in the laboratory using destructive method. The drilling fluid density and rheological properties were measured using mud balance and 900-Viscometer
®
, respectively. The results of this work showed that, for sand content less than 10 wt%, the mechanical properties of the drilled cutting have no effect on drilling fluid properties. The effect of the mechanical properties of the drilled cutting becomes more significant for sand content greater than 10 wt%. In this range of sand content (> 10 wt%), for a constant UCS, drilled cutting with a smaller Young’s modulus have a higher effect on the drilling fluid rheological properties compared to drilled cutting with a larger Young’s modulus. On the other hand, for a constant
E
, drilled cutting with larger UCS showed a higher effect on the drilling fluid rheological properties compared to drilled cutting with smaller UCS values.
Adding lubricant additives is a predictable method to decrease the frictional resistance in oil and gas drilling applications. In this work, tribological studies were carried out for drilling fluid ...with/without lubricant additives at different temperatures up to 200 °C and environmental pressure of 3.45 MPa. In pure fluid, additive A exhibited higher load capacity, compared to additive B at 200 °C. In drilling fluid, at 75 °C, all additives decreased the COF. However, at 125 °C and 175 °C, the additives did not decrease the COF but decreased the standard deviation of the COF values. SEM/EDS analyses were used to investigate the wear mechanisms and it was deduced that the viscosity of the drilling fluid played an important role in determining the friction and wear performance.
•Tribological studies of drilling fluid with/without lubricant additives up to 200 °C and 3.45 MPa.•In pure fluid, additive A showed higher load capacity, and additive B chemical degradation.•Under realistic drilling fluid (mud) conditions, all additives decrease the COF at 75 °C.•At extreme temperatures, abrasive particles in the drilling fluid played a critical role.
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