Yield Point Research Articles

Optimum formulation design and properties of drilling fluids incorporated with green uncoated and polymer-coated magnetite nanoparticles

Nanomaterials are materials that possess unique properties due to their high specific surface area and quantum effects. Nanomaterials have diverse applications in different fields including the petroleum and gas industry as additives. One of the classes of nanomaterials that currently have potential usage in the downstream, midstream, and upstream processes of the petroleum industry is nanoparticles (NPs). Among the upstream processes in the petroleum and gas industry is the drilling operations. It is popular that the most critical features that ensure the success of a drilling operation are the rheological and filtration loss characteristics of the drilling fluid. The current work deals with the synthesis of green uncoated and polymer-coated green magnetite nanoparticles (MNPs). The MNPs were characterized and assessed as rheology and filtration loss modifiers for water-based drilling fluids. The optimum formulation design of drilling fluids incorporated the MNPs for high-performance drilling fluids in terms of density, rheological, filtration loss, and sagging properties was identified. The effect of temperature (ambient − 80 °C), and aging time (6–248 h) on the investigated properties were evaluated. The results confirmed that optimum values for plastic viscosity, apparent viscosity, yield Point, gel strength (10sec), gel strength (10 min), mud thickness, and sag index were 13.77 cP, 69.69 cP, 89.87 lb/100ft2, 86.75 lb/100ft2, 128.38 lb/100ft2, ≤ 1 mm, and 0.511, respectively. Most of those values could be reached using an optimum formulation involving 0.92 % MNPs at ambient temperature. Increasing the temperature displays a decrease in the values while increasing the aging time displays an increase in the values. Drilling fluids with MNPs showed insignificant changes in the investigated properties with increasing temperature in particular those incorporated with polymer-coated MNPs compared to the water-based drilling fluids.

Yield stress analysis of cellulose nanocrystals (CNCs) in hyaluronic acid suspensions

Due to their biodegradability features, cellulose nanocrystals (CNCs) and hyaluronic acid (HA) have been simultaneously used in the matrix of hydrogels for biomedical applications, such as corneal transplantation, and skin regeneration. Although rheology of these hydrogels may provide useful information for their applications, little to no attention has been paid to rheological characterization. In this study, we analyzed the rheology of HA-CNC suspensions and more specifically their yielding behavior. Through different rheological experiments, known as stress ramp, shear rate ramp and amplitude sweep; it was observed that HA-CNC gels possessed two yield points. Reproducible magnitudes of yield stress were obtained by optimizing the experimental conditions. The rheo-optics characterizations confirmed that the first and second yield points could be attributed to the bond and cage breakage phenomena. Studying the effect of concentration, the second yield stress increased linearly by CNC concentration, whereas the first yield point manifested a power-law dependence on concentration (exponent of 0.5). This power-law relationship was further justified by the evolution of average distance between the CNC individual particles (d), calculated through SAXS analysis.

Water-based drilling fluids containing hydrophobic nanoparticles for minimizing shale hydration and formation damage

Wellbore instability is always inevitable in shale formation due to hydration, swelling, and dispersion of clay, especially when using water-based drilling fluids (WBDFs). To mitigate the wellbore instability of shale formation and avoid correlative detriments such as formation damage, various nano-silica particles (nano-SiO2) were employed to plug the nano-sized pores, inhibit water invasion into shale, and prevent shale swelling. Firstly, the influence of various nano-SiO2 on rheological and filtration properties of a set WBDF was evaluated. Then, the linear swelling test, shale recovery test, zeta potential test, imbibition test, contact angle measurement, scanning electron microscopy (SEM) observation, and computed tomography (CT) analysis were conducted to assess the characteristic of nano-SiO2. Experimental results showed that solid phase nano-SiO2 could dramatically increase the viscosity and yield point while liquid phase nano-SiO2 only caused small fluctuations on these parameters. Besides, hydrophobic nano-SiO2 displayed better filtration performance than hydrophilic nano-SiO2. On the whole, the hydrophobic nano-SiO2 dispersion, called as nano-2, showed the best performance in WBDFs. Furthermore, nano-2 exhibited better inhibition than hydrophilic nano-SiO2, KCl, and polyether amine (PA). Mechanism analysis demonstrated that nano-2 could improve the hydrophobic degree of shale surface and prevent water from contacting with the shale. Meanwhile, nano-2 plugged the pores and throats in the shale. As a consequence, water in the drilling fluid was prevented from invading the shale, and the shale was inhibited. Nano-2 could form a thin barrier in the surface of shale, and mitigate the damage degree of shale cores after perforation operation. As a result, nano-2 displayed great potential to stabilize shale and protect formation in WBDFs.

Development of a “Green” Emulsion with a Milk Protein Hydrolysate: An Evaluation of Rheology, Texture, In Vitro Bioactivity, and Safety

Bioactive peptides are promising cosmetic active ingredients that can improve skin health and appearance. They exhibit a broad spectrum of activity, including anti-aging, antioxidant, antimicrobial, and anti-inflammatory effects. The aim of this study was to develop a safe, stable, and efficacious environmentally friendly (“green”) emulsion using a milk protein hydrolysate as a model active ingredient. Potential emulsions were formulated with biodegradable emollients, stabilized with naturally derived mixed emulsifier, and prepared by cold process. They were evaluated for rheological behavior (continuous rotation and oscillation tests), physical stability (dynamic mechanical thermal analysis—DMTA test), and texture profiles, as well as cytotoxic, antioxidant, and antimicrobial effects. Rheological characterization revealed shear-thinning flow behavior with yield point from continuous rotation tests and predominantly elastic character from oscillation (amplitude and frequency sweep) tests, with small structural change detected in the DMTA test. These results implied satisfactory rheological properties and good stability. Texture analysis revealed acceptable spreadability and substantivity of the emulsions. The protein hydrolysate showed antioxidant activity. The developed emulsions showed low antibacterial activity against selected microorganisms, but this was due to the action of preservatives, not peptides. All potential emulsions showed a desirable safety profile. The results obtained provide the basis for the next stage of formulation development, i.e., in vivo efficacy tests.

Mechanical properties and moisture diffusion in hot-pressed jute fiber composite subjected to hygrothermal ageing

Jute fiber is one of the most extensively used eco-friendly natural fibers that are hydrophilic. The performance of natural fiber-reinforced composites is affected by the diffusion of heat and moisture from the environment in addition to the exposure time. In the present investigation, the ultimate tensile strength, displacement at fracture, and energy at yield of the jute fiber-reinforced composite under different hygrothermal (temperature and relative humidity) conditions are investigated. The samples were prepared by hand lay-up technique and the laminates were hot pressed on a hydraulic press apparatus. The specimens were further exposed to a hygrothermal environment using a humidity cabinet (with an inbuilt thermometer and hygrometer) for varied intervals of time of 4, 16, and 64 h. The longitudinal tensile stress ( σ) increased at lower hot-pressing temperatures and minimum hygrothermal ageing and it decreased at a higher temperature. Upon increase in hygrothermal ageing, σ decreased at all temperatures. The energy at yield point ( E) decreased significantly at lower temperatures and minimum hygrothermal ageing while minimum changes were observed at a higher hot-pressing temperature. The diffusion of moisture as a function of time and temperature explained using Fickian law. The initial region showed nearly linear variation. With continuous hygrothermal ageing, the equilibrium, considering partial pressure, was achieved between the environment and moisture inside the sample. The microstructure of the sample processed at lower hot-pressing temperatures followed by hygrothermal ageing of 16 h showed diffusion and fiber pull-out. However, at a higher temperature, matrix cracking was also observed.

Soil–Water Retention Curve Prediction for Compacted London Clay Subjected to Moisture Cycles

The evolution of the hydraulic properties of London Clay when compacted at a range of initial conditions (density and water content) was investigated. The soil–water retention curve (SWRC) is observed to change as the soil is subjected to cycles of wetting and drying. A new method is presented for predicting these changes in the soil–water retention curves (SWRCs) based on the starting conditions for each cycle. The method is based on relationships between the degree of saturation before drying (Sr,i), which includes the effect of void ratio and soil fabric, and key parameters that characterize the shape of SWRCs (air-entry value and slope of the transition zone). The relationship between the Sr,i and the air-entry value (or yield point, YP), and the relationship between the YP and the slope of the transition zone of the SWRC were established for the large experimental data set of two types of London clay of high and very high plasticity. The fitting parameters of a bi-linear SWRC model were estimated and used to constrain the fitting parameters of the van Genuchten model. As the SWRC of compacted clay continuously changes with progressive moisture cycles, this model allows the prediction of this evolution for the modelling of earthworks over the years, when subject to changing climatic conditions, without the need for an extensive experimental program.

Cyclic behavior of self-centering RCFST column to beam joints with prefabricated connectors

This paper presents the cyclic behavior of reinforced concrete-filled steel tube (RCFST) column to beam joint with prefabricated connectors. The cyclic performance of four specimens was investigated to focus on the hysteretic behavior, reinforcement tension, residual deformation, and strain distribution of joints. The equivalent viscous damping coefficients (ξeq) corresponding to the four specimens range from 0.049 to 0.087 at the yield point. And the final residual drift ratio of the specimens ranged from 3.6% to 12.9%. The tested column-beam joint specimens had good hysteretic behavior, energy dissipation, and self-centering ability. The PT steel bars without hollow channel or weakened treatment enhanced the self-centering ability and workability of joints. The finite element models were developed to verify the main mechanical properties of the self-centering RCFST column to beam joint. The average of KE/ KFEA, Mc,y/ My,FEA and Mc,p/ Mp,FEA were 0.89, 0.98, and 1.03, respectively. The FEA models could predict mechanical properties of the joints with high accuracy.

Microstructure evolution under thermo-mechanical operating of rocksalt-structure TiN via neural network potential.

In the process of high temperature service, the mechanical properties of cutting tools decrease sharply due to the peeling of the protective coating. However, the mechanism of such coating failure remains obscure due to the complicated interaction between atomic structure, temperature, and stress. This dynamic evolution nature demands both large system sizes and accurate description on the atomic scale, raising challenges for existing atomic scale calculation methods. Here, we developed a deep neural network (DNN) potential for Ti-N binary systems based on first-principles study datasets to achieve quantum-accurate large-scale atomic simulation. Compared with empirical interatomic potential based on the embedded-atom-method, the developed DNN-potential can accurately predict lattice constants, phonon properties, and mechanical properties under various thermodynamic conditions. Moreover, for the first time, we present the atomic evolution of the fracture behavior of large-scale rocksalt-structure (B1) TiN systems coupled with temperature and stress conditions. Our study validates that interatomic brittle fractures occur when TiN stretches beyond its tensile yield point. Such simulation of coating fracture and cutting behavior based on large-scale atoms can shed new light on understanding the microstructure and mechanical properties of coating tools under extreme operating conditions.

Grafted graphene oxide nanoparticles as a yield point enhancer in water-based drilling fluids

Drilling fluids are used in exploration and production (E&P) for oil/gas. More recently, nanomaterial additives such as nano clay, nano-silica, nanocellulose, etc., have been of interest in improving drilling fluids' performance. Graphene and oxide (GO) nanomaterials have been attractive for oil-field applications. Furthermore, water-based drilling fluids are more environmentally desirable than oil-based fluids. This study demonstrated the successful synthesis and use of bi-facial grafted graphene oxide with two random copolymers and one block copolymer for water-based drilling mud application. The successful polymerization was verified by FTIR spectroscopy, EGA, DLS, and Raman spectroscopy. The dispersity and stability of GO-AMPS-r-DMA were tested in different water-based and oil-based solvents, indicating better dispersity and stability in water and DMF than GO. The thermal behavior of the three GO-polymer composites was studied by TGA, DSC, and EGA, showing higher stability with block copolymers than random ones. The performance of such grafted graphene materials was tested in water-based drilling fluids at simulated downhole temperatures and pressures. Results demonstrate the positive effect of these produced grafted graphene materials on mud rheological behavior at temperatures up to 350F and 10,100psi.

Welding of P355NH steel for the construction of a medium-pressure gas pipeline

AbstractThere is an increasing demand for welding of steel pipes meant for pressure purposes. P355NH (1.0473) steel became an important construction material used for structuring and restructuring of a medium-pressure gas pipeline due to its properties, such as significant tensile strength at the level of 600 MPa and increased yield point. These properties ensure appropriate service life of the principal pipeline structures. When welding P355NH steel, processes that enable high-quality welds without significant changes in the chemical composition of the base material, are applied. It is recommended to use the TIG welding process to produce joints, although P355NH steel joints are considered as difficult to weld. During welding, various welding defects might appear, which mainly include sticking and lack of fusion. Creation of joints with the desired properties, including those used in the construction of medium pressure gas pipelines, with the required class B quality, requires selection of appropriate parameters and compliance with the welding process practice. This is very important for the service life of the structure. Therefore, the article aims to select the most appropriate parameters and thermodynamic conditions for welding P355NH steel in order to obtain the best mechanical properties. The most important of the tested welding parameters of P355NH steel is welding speed, welding current, preheating temperature, interpass temperature and, above all, the role of various shielding gases. (Three different shielding gases containing argon and helium additives were tested.) The obtained joints were tested by: non-destructive tests, such as VT—visual examination; MT—magnetic particle testing, PT—penetration tests, UT—ultrasonic testing and by the destructive methods, such as tensile strength, impact toughness, bending test, light microscopy and scanning electron microscopy. The cause-and-effect relationships between the obtained joint structure and its mechanical properties were determined. The considerations were supported by the nucleation model and the mechanisms of formation of the acicular ferrite phase in the joint material. The chosen parameters of TIG process allow to obtain joint with adequate strength for the production of the gases pipeline, without welding defects. The results have a practical implication, the developed production technology for the obtaining the joints. The presented solution gives the possibility of producing correct welded joints, which can be used in the responsible steel construction. The originality of manuscript is the presentation the newly, uncomplicated solution of obtaining joint with good mechanical properties included the thin-walled tubular structure with a thickness of 3.6 mm. A novelty in the article is a clear indication of the importance of detailed thermodynamic welding conditions and obtained weld structure on the mechanical properties of the P355NH steel joint, which lead to the formation of various non-metallic titanium inclusions, which have a decisive impact on the mechanical properties of the joint, especially its strength and impact strength.

Optimizing the seismic resilience performance of steel truss bridges by maximum energy dissipation via friction dampers

The primary aim of this study is to propose an innovative design methodology for optimizing the seismic resilience performance of steel truss bridges by dissipating the maximum input seismic energy. Maximum seismic energy dissipation is carried out by means of Pall friction dampers (PFDs), popularly categorized among passive energy-damping devices. PFDs distribute input seismic energy with a slip motion along with friction during an earthquake. For that, it is important to determine the optimal slip load value for the PFDs to start working before the structural elements reach the yield point. To determine the optimal slip load values of the PFDs under earthquake effects, the maximum seismic energy distribution is assured by nature-inspired Squirrel Search (SS) and Water Strider (WS) metaheuristic algorithms for steel truss bridges equipped with PFDs. Finally, steel truss bridges on which PFDs with optimal slip load values have been implemented are optimally designed to achieve the minimal structural weight while satisfying ASD-AISC Code of Practice requirements. In order to demonstrate the validity of the proposed design methodology, two design examples of 113-member and 465-member steel truss bridges steel are presented. The optimal slip loads attained with the SS and WS algorithms by conducting the proposed design methodology are 2.45% and 3.75% of the structural weight for the first design example and 2.64% and 2.63% of the structural weight for the second design example, respectively, which are much lower than those considered in practical applications. Moreover, the numerical results show that by 93.5% and 99.48% maximum distribution rates of input seismic energy are accomplished in the bridges. The results indicate that the proposed design methodology exhibit superior performance in optimizing the seismic resilience performance of steel truss bridges by maximum energy dissipation via friction dampers.

Analysis of a drilling mud-based system on the common problems related to coiled tubing application in slim-hole oil wells

Coil tubing is slim and looks like a long, continuous length of pipe made from carbon steel metal that is a lesion on spool that is 1 to 3.25 inches in diameter of 26,000 feet long. The main benefit of coil tubing in drilling operations over wireline jobs is the ability to pump chemicals through the coil and the ability to push it into the hole rather than relying on gravity. Inappropriate selection of the drilling mud is one of the contributing factors to hole problems. Different experiments were conducted to determine the mud rheology of multiple mud samples. Certain parameters, like the critical velocity, are calculated using a numerical approach for the coiled tubing applications. In addition, it is crucial to determine the pump pressure required to maintain a specific flow rate. It is noted that drilling operations become more efficient at lower plastic viscosities; however, plastic viscosity is reduced through dilution; hence, the rate of penetration is improved. Moreover, a higher yield point is capable of transporting the cuttings more effectively than a lower yield point. The critical velocity indicated the boundaries between the laminar and turbulent flow regimes. As the mud flow rate inside the tubing increased, the velocity increased, causing the shear stress at the tubing wall to increase.

Reaching the Yield Point of a Glass During X-Ray Irradiation

Reaching the Yield Point of a Glass During X-Ray Irradiation

The Development of Advanced Fluorescent Tracers Aimed at Drill Cuttings Labelling and Depth Correlation via Injection with Oil-Based Drilling Mud

Fast and precise geo-steering and geo-navigation upon well drilling are the key parameters for improved well targeting, optimal well placement, and maximal hydrocarbon recovery. To advance geo-steering parameters, we propose a new approach to on-site formation evaluation through the use of fluorescent tracers for drill cuttings tagging according to the depth of origin. Cuttings labelling at the drill bit site is followed by near-real-time drilling depth correlation at the well-head via a camera and AI image recognition systems. To suite the drilling process, the engineered tracers should match to the rheology of the utilized drilling mud. This study was performed to comprehensively investigate the effect of fluorescent tracers on the rheological properties of oil-based drilling mud (OBM) and to determine the optimal quantities of the tracers’ addition. We evaluated critical mud characteristics including electrical stability, thixotropic parameters, shear stress, gel strength, plastic viscosity, and yield point as prepared and in the presence of fluorescent tracers at the range of 1 to 20 wt.%. Additionally, the mud’s effects on the long-term stability of the fluorescent tracers were assessed via hot-rolling tests in conditions mimicking downhole conditions, with the aim of determining the tags’ feasibility for drill cuttings labelling applications. The study also examines the recovery potential of the tracers and their reusability in the drilling process. This investigation provides valuable insights into the potential application of fluorescent tracers for downhole drill cuttings depth correlation which will improve geo-steering works.

Minimizing the particles settling of ilmenite weighted oil well cement using laponite

Cementing operations are fundamental undertakings during the drilling and completion of oil and gas wells, ensuring zonal isolation and structural stability within the wellbore. Ilmenite serves as a dominant weighting material for high-density cement. However, challenges associated with its particle settling have arisen, reporting the potential for various complications within the cement sheath. In this context, the present study used laponite, a synthetic layered clay, to address the issue of particles settling in ilmenite-weighted oil well cement under high pressure and high-temperature curing conditions. The investigation extended to comprehensively assessing the consequences of incorporating laponite on the cement's rheological, mechanical, and petrophysical properties. Varied concentrations of laponite were employed and compared against the base cement, devoid of laponite. A total of six high-density cement samples of 18 ppg at different concentrations of laponite were prepared under a high pressure of 3000 psi and a high temperature of 294 °F. Findings from this work revealed that an optimal laponite concentration of 0.3% by weight of cement (BWOC) appeared to be the most effective. Adding laponite to the cement led to an impressive 83% reduction in particle settling within ilmenite-weighted cement. This deduction was confirmed through the direct density variation method and NMR measurements. Moreover, the inclusion of laponite yielded favorable outcomes in the rheological aspects of oil well cement. Laponite-based cement showed a 40% reduction in plastic viscosity and a 31.5% and 14.5% increase in yield point and gel strength, respectively, compared to the base cement formulation. Mechanically, laponite had a tangible positive impact, evidenced by a 95% and 131% increase in compressive and tensile strengths, respectively and a 16% reduction in Young's modulus, all relative to the base cement sample. Significantly, laponite's role extended to pore space optimization, leading to a decline in cement porosity by 2% and a 25% reduction in permeability.

Evading the strength-ductility compromise in medium manganese steel by a novel low temperature warm rolling treatment

Strength-ductility trade-off is an enduring problem in a wide range of metals and alloys including the advanced high-strength steels. In this work, we propose a novel non-isothermal low-temperature warm rolling (WR) treatment which was applied after the conventional intercritical annealing (IA) in order to overcome the strength-ductility compromise in a medium manganese steel, Fe-5.1Mn-0.22C-0.85Si-0.42Al (composition in wt%). IA + WR treatment yielded a simultaneous improvement in tensile properties, wherein yield strength (YS), ultimate tensile strength (UTS), and ductility improved by 32%, 12%, and 6% respectively, compared to the conventional IA treatment. Despite an increase in the yield point elongation (2%) and Lüders strain (3%) in the IA + WR specimen, the ductility of the same improved as compared to the IA specimen. Microstructure of the IA + WR specimen was tailored by introducing a significantly higher dislocation density in the constituent ferrite and retained austenite (RA) phases along with a relatively higher density of planar defects (stacking faults and nano-twins) in the RA phase. X-ray line profile analysis quantified the increased dislocation density (order ∼1015 vs 1014 m−2) and twin fault probability (∼1.35% vs ∼0.12%) in the RA phase of the IA + WR compared to the IA specimen. The improvement in YS was primarily due to the increase in the dislocation density of the constituent phases in the IA + WR specimen. Introduction of a high density of lattice defects in the RA phase during the WR treatment above the Md30 temperature enhanced the mechanical stability of the RA phase, leading to a decreased rate of TRIP effect and formation of hierarchical twins during tensile deformation. The near-ubiquitous strength-ductility trade-off was overcome via a tailored microstructure consisting of regulated austenite stability leading to discontinuous TRIP effect, hierarchical twinning in RA phase, and favorable texture in the constituent phases. The present study provides a pathway to tailor the microstructure for escaping the strength-ductility paradox in different metastable FCC alloys such as stainless steel, HEAs, TWIP steels etc.

Improving Atmospheric Water Harvesting in Carbon‐Based Sorbents Through CO2 Activation

AbstractAtmospheric water harvesting (AWH) can serve as an alternative fresh water source in regions with scarce access to drinking water. While many techniques are geographically or seasonally limited, sorbent‐based AWH shows the potential for wider application. Low‐cost, carbon‐based sorbents named nanoporous sponges (NPS) are recently developed, exhibiting fast and repeatable water uptake of 0.14 g g−1 at 90% relative pressure. While useful from a cost and daily water yield point of view, there is room for improvement. This article presents an improved production process combining pyrolysis and activation under CO2 in a single step, yielding improved NPS capable of reproducibly reaching a water uptake of 0.47 g g−1 at 95% relative pressure while maintaining fast sorption rates. The NPS show significant endurance and are able to maintain stable performance over numerous humidity cycles. An unexpected time‐dependant sorption behavior is also identified for NPS produced with a modified synthesis formulation, due to an increase in sodium carbonate residual content.

Hysteretic behavior of replaceable low yield point steel links with corrugated web

To develop a new replaceable steel link with high energy dissipation capacity for establishing a rapid recoverable system of bridge piers, a novel demountable and replaceable low yield point steel links with corrugated web (LCSW link) is proposed. A series quasi-static test on six specimens was conducted to investigate their failure process and hysteretic behaviors, considering the effects of different material and shape of the webs, as well the height-to-span ratio of the replaceable link. The experimental results indicate that the LCSW links exhibit three types of failure modes: the local buckling of steel flanges, the welding fracture at flange-to-endplate connection, and the combination of welding fracture at flange-to-endplate connection and shear buckling of CSWs. The hysteretic behaviors of the specimens were mainly affected by the height-to-span ratio. Moreover, utilization of a small height-to-span ratio (1.7 in this paper) and low yield point steel (LYP160 steel) in the links improves the ductility and energy dissipation capacity. Three-dimensional nonlinear finite element models were established to simulate the hysteretic behavior of the LCSW links, and the yield strength and initial stiffness of the LCSW links under lateral loading were obtained through finite element simulation and simplified design method. The comparison of experimental and analytical results indicates that the finite element models were able to simulate the cyclic response well, and these proposed theoretical equations can be used efficiently to predict the capacity of LCSW links.

Experimental Study of a Degradable Solid-Free Drill-In Fluid System and Its Reservoir Protection Mechanism

Summary The traditional drill-in fluid used to construct open holes does not mitigate problems that arise in subsequent completion operations and the risk of formation damage. In this work, a degradable solid-free drill-in fluid was designed with excellent direct flowback and degradation capabilities to reduce potential reservoir damage. A new type of viscosifier (XC-LT), as the key additive in the solid-free drill-in fluid, was prepared by modifying xanthan (XC) with maleic anhydride, and its phase transition temperature (Tm) was 20°C lower than that of XC alone. The XC-LT molecules in an aqueous solution were completely degraded after standing for 3 days, resulting in a clear solution with minimal residue. Additionally, in our proposed degradable solid-free drill-in fluid system, the stability of XC-LT could be improved significantly due to the existence of other additives, including filtrate reducer, monoethanolamine (MEA), potassium chloride (KCl), and sodium sulfite (Na2SO3). After aging for 3 days, the degradable solid-free drill-in fluid system constructed with XC-LT and other additives still had good rheological properties, and the rheological parameters, such as apparent viscosity (AV), plastic viscosity (PV), and yield point (YP), remained relatively stable, meeting the requirements for carrying cuttings in the drilling process. Its low shear rate viscosity (LSRV) was 30 900 mPa·s, and the system had good degradation performance after standing for a long time, which can reduce the flowback breakthrough pressure of oil and gas resources. The permeability recovery values (Kod/Ko) of the contaminated cores with the degradable solid-free drill-in fluid were greater than 94%, and the degraded drill-in fluid could fully flow back through the pore throats, reflecting an excellent reservoir protection performance. Finally, the degradable solid-free drill-in fluid system was applied to wells in the South China Sea. Compared with the adjacent wells using the solid-free drill-in fluid and gel-breaking fluid systems, the well production using our proposed degradable solid-free drill-in fluid system exceeded the anticipated production and was much greater than that of the adjacent wells. Our proposed degradable solid-free drill-in fluid system had good reservoir protection performance, and its application simplified the completion process.

Bentonite-Based Drilling Boyolali Mud Fabrication with Additive Carboxymethyl Cellulose, Na2CO3 and KOH

This study aimed to examine the effect of adding KOH, Na2CO3, and Carboxymethyl Cellulose additives on the physical properties of the mud, as well as the optimal additive for sludge production. The preparation of the basal sludge involved the addition of 22.5 grams of bentonite, 350 millilitres of distilled water, and 10 grams of Barite as a constant variable. Then it stated 0.5 variations of the Na2CO3 additive; 1.5; 3 grams, KOH 0.5; 1.5; and 3 grams, and Carboxymethyl Cellulose 3; 6; and 9 grams. A physical property measurement involving density was conducted. Samples were evaluated for Plastic Viscosity and Yield Point at 300 and 600 rpm dial speeds. After 30 minutes of filter press compression, the filtration loss, mud cake, and pH were measured. The results indicate that the KOH additive decreases Yield Point by 8.6 lb/100ft2 and increases Filtrate Loss by 5.8 mL and sediment pH by 11.12 points. The additive Na2CO3 then causes a reduction in Filtrate Loss of 10.4, 8.8, 7.6 mL and an increase in Plastic Viscosity. While Carboxymethyl Cellulose can increase Plastic Viscosity by 7; 13; 55 cP, Gel strength by 4; 6; 40 Lb/100 ft2, and Filtrate Loss by 10; 8; 7.6mL. Carboxymethyl Cellulose is the additive that has the most significant effect on the physical properties of the mud because it can affect Plastic Viscosity, Gel Strength, Yield Point, and Filtrate Loss so that the soil can approach API 13A Standards. The optimal amount of Carboxymethyl Cellulose should be added at a mass of 6 grams, or 13 cP.