Mud Rheology Research Articles

Filter Cake Neural-Objective Data Modeling and Image Optimization

Designing drilling mud rheology is a complex task, particularly when it comes to preventing filter cakes from obstructing formation pores and making sure they can be easily decomposed using breakers. Incorporating both multiphysics and data-driven numerical simulations into the design of mud rheology experiments creates an additional challenge due to their symmetrical integration. In this computational intelligence study, we introduced numerical validation techniques using 498 available datasets from mud rheology and images from filter cakes. The goal was to symmetrically predict flow, maximize filtration volume, monitor void spaces, and evaluate formation damage occurrences. A neural-objective and image optimization approach to drilling mud rheology automation was employed using an artificial neural network feedforward (ANN-FF) function, a non-ANN-FF function, an image processing tool, and an objective optimization tool. These methods utilized the Google TensorFlow Sequential API-DNN architecture, MATLAB-nftool, the MATLAB-image processing tool, and a single-objective optimization algorithm. However, the analysis emanating from the ANN-FF and non-ANN-FF (with neurons of 10, 12, and 18) indicated that, unlike non-ANN-FF, ANN-FF obtained the highest correlation coefficient of 0.96–0.99. Also, the analysis of SBM and OBM image processing revealed a total void area of 1790 M µm2 and 1739 M µm2, respectively. Both SBM and OBM exhibited notable porosity and permeability that contributed to the enhancement of the flow index. Nonetheless, this study did reveal that the experimental-informed single objective analysis impeded the filtration volume; hence, it demonstrated potential formation damage. It is, therefore, consistent to note that automating flow predictions from mud rheology and filter cakes present an alternative intelligence method for non-programmers to optimize drilling productive time.

Influence of triton-assisted coconut shell derived graphene nanoplatelets in water-based drilling fluid lubricity and shale inhibition application

Insufficient hole cleaning, cutting suspension, clay swelling, and filtrate invasion of the formation might result from inadequate drilling mud properties. For effective drilling and wellbore stability, water-based mud (WBM) rheology, lubricity, filtration, and shale inhibition must be optimized and controlled. WBMs react with clays and cause time-dependent borehole issues, which is their principal drawback. Moreover, prolonged exposure destroys certain WBM components, resulting in minimal mud properties. These indicate the need for multifunctional additives to improve WBMs. Thus, this study developed WBM systems employing graphene nanoplatelets (GNPs) and locally acquired discarded coconut shells to overcome severe drilling challenges. By adding triton-X100 to coconut shell-based graphene (GN-CS), a greater dispersion of modified graphene (GN-TX) particles was produced. Characterization, rheology, lubricity, inhibition, and filtration tests were performed on these GN-CS and GN-TX at concentrations of 0.125, 0.25, 0.375, and 0.50 wt%. Furthermore, biotoxicity, biodegradability, and heavy metal content experiments were performed to study the environmental impact of GN-CS and GN-TX. The results showed that GN-TX had good thermal resistance up to 300 °C with only a 10% loss in weight. Both EDX and FTIR tests showed that the epoxy, carboxyl, and hydroxyl groups are in the GNP-based materials' basal plane. The GN-CS and GN-TX had better fluid properties, including better lubricity, rheology, filtration, and inhibition over the base mud, and the optimal rheological model of the drilling muds was the Herschel Buckley model. The GN-TX (modified) decreased the fluid loss to 20.6–14.3 mL from 24.6 mL at 353 K, whereas the GN-CS (unmodified) reduced it to 21.3–16.7 mL. GN-TX and GN-CS decreased the coefficient of friction of WBM from 0.47 to 0.55 to 0.25–0.41 and 0.33–0.44, respectively, from 298 to 353 K. In addition, 0.50 wt% of GN-CS and GN-TX reduced the shale pellet swelling height to 5.4% and 5.6%, respectively, from 8.8%. Moreover, the EC50 values for GN-CS and GN-TX were about 54,000 mg/L and the BOD/COD ratio was about 47%. These results show that the GNP-based products are safe and biodegradable. The GNP-based materials have promising prospects for drilling in environmentally sensitive formations.

Application of black tea waste as eco-friendly deflocculant and rheology stabilizer for water-based mud

Maintaining and regulating the rheological properties of the drilling mud at the desired level is essential for successful drilling operations. Bentonite is the key additive used in most water-based drilling mud for enhanced rheological properties. However, the flocculation tendency of bentonite particles poses a significant challenge for the industry due to the undesirable and unpredictable changes in rheological properties of the fluid with downhole increasing temperature. This study aims to develop a low-cost and eco-friendly deflocculant from black tea waste (BTW) that can prevent the aggregation and flocculation of the bentonite and stabilize the rheology of bentonite-polymer muds. Rheological properties were evaluated with different concentrations (0.25%, 0.5%, 0.75%, and 1%) of BTW at 95 °F and 140 °F. The Bingham Plastic (BP) and Power Law (PL) models were studied to characterize the flow behavior and identify the best-fit model through statistical analysis. Along with rheological properties, thinning efficiency, mud stability, thermal aging effect, thixotropic behavior, and shear thinning behavior were investigated through different shear-temperature-time dependent tests. In addition, the lubricating properties and filtration loss characteristics were assessed at ambient conditions. Finally, the findings were compared with the industrially used deflocculant, lignosulphonate (LS). The results revealed that BTW can effectively prevent bentonite flocculation and stabilize the mud rheology even at a very low concentration of 0.25%. Significant improvements were observed in the lubricating and filtration characteristics. With the addition of 1% BTW, the filtrate loss, mud cake thickness, and friction coefficient were reduced by 22.2%, 50%, and 13.29%, respectively. The multifunctional activities of black tea waste (BTW) are attributed to its polyphenolic compounds, the presence of which was confirmed through UV–visible spectroscopy testing. The TG analysis confirmed that BTW remains thermally stable up to 200 °C. Considering the synergistic performance compared with lignosulphonate, availability, and environmental and economic acceptance, BTW may be effectively utilized as a multifunctional deflocculant and rheology stabilizer for water-based bentonite-polymer muds.

Estimation of Surge and Swab Pressures While Tripping for Minimizing Excessive Drilling Problems

Surge and swab pressures result from pipe movement upward/downward during drill string reciprocation and tripping. surge and swab create costly drilling concerns such well kick, formation breakage, and lost circulation. This study aims to find the optimum pipe tripping speed to avoid surge and swab issues, particularly in lost circulation zones. Also, to determine how drilling factors and well bore geometry affect surge and swab pressures. Mud rheology, mud properties, hole diameters, drill pipe diameter, and bottom hole assembly (BHA) dimensions were also analyzed. Dynamic surge and swab model was employed to simulate two case studies in Rumaila Iraqi oilfield. The findings indicated that the tripping speed is the most effective variable on surge and swab pressures. Annular clearance and BHA design have also a major effect on the surge and swab pressures. For the first case study, it is found that whenever the mud weight is far from the pore pressure and fracture pressure gradients, the 5" drill pipe can be tripped in/out of lost circulation formation (Shuaibba formation) at optimum tripping speed of (80 ft/min) without surge/ swab related problems. The reason is that the generated surge pressures (6110-6300 psi) are below the fracture pressure (7100-7400 psi). The results also showed that tripping 5" drill pipe within a maximum running speed of 80 ft/min in (8.5") open hole section through Tanuma formation till Rumaila formation causes a surge pressures of (4650-5050 psi) which is still below the fracture pressures of formations (4750-5660 psi). the results of the second case study (S-shaped well) revealed that the optimum tripping speed of the drill string in the (12.25") open hole through Dammam and Hartha formations is (90 ft/min). it is also concluded that pulling out of hole (POOH) process must be carried out more carefully than the running process since the mud density is near the pore pressure gradient. The results of this study can be further used to improve the drilling efficiency in Rumaila oil field with decreasing non-productive time (NPT) by employing the appropriate tripping speed and optimal drilling operations.

On Improving Water-Based Drilling Mud Swelling Control Using Modified Poly(Vinyl Alcohol)s.

One of the most challenging issues when drilling under high-temperature, high-pressure (HT/HP) conditions is wellbore instability caused by clay swelling and fluid loss of the drilling mud. One of the most difficult issues when drilling under high-temperature, high-pressure (HT/HP) conditions is wellbore instability caused by clay swelling and fluid loss in drilling mud. Two modified PVOHs, nonionic and cationic polymers made from sodium bentonite clay and deionized water at concentrations of 0.08, 0.28, and 0.49 wt.%, were introduced to WBM percent. A series of specific gravity and mud rheology experiments at 25, 55, and 85 °C indicated that both values drop monotonically with increasing temperature, regardless of PVOH addition or concentration. A temperature increase of 30 °C decreases the mud viscosity of WBM (without PVOH) by 18% from its starting value, on average. Only 0.1% of cationic and nonionic polymer reduces viscosity by 10% and 0%, respectively. Experimenting with mud samples for 5 h revealed that adding nonionic polymers enhances mud filtration by up to 34.7%, 1.25 times more than that achieved from cationic polymers under the same filtration circumstances. Increasing the filtration temperature moderately affects mud cake generation due to increased mud swelling index and preferential adsorption by nonionic polymer. The latter observation was corroborated by determining the polymer content of the filtrates. Therefore, it was shown that nonionic polymers adsorbed more (118.9 mg/g) than cationic polymers (84.51 mg/g). Increased filtration temperature moderately affects mud cake generation due to increased mud swelling index and preferential adsorption by nonionic polymer. The latter observation was corroborated by testing the filtrates for the polymer content. As a result, it was discovered that nonionic polymer adsorbed more (118.9 mg/g) than cationic polymer (84.51 mg/g). Thermogravimetry analysis (TGA) finally tested the thermal stability of polymers.

Fully Coupled CFD–DEM Simulation of Oil Well Hole Cleaning: Effect of Mud Hydrodynamics on Cuttings Transport

This paper presents a coupled computational fluid dynamics–discrete element method (CFD–DEM) simulation to predict cuttings transport by the drilling fluid (mud) in different oil well drilling conditions. The mud rheology is expressed by the Herschel–Bulkley behaviour and modelled in a Eulerian framework (CFD), while the cuttings are modelled using the Lagrangian approach (DEM). In this work, the effects of drill string rotation, inclination angle, cutting size, mud rheology, and annular velocity on cleaning efficiency are investigated. It is found that increasing the well deviation from vertical to horizontal leads to a higher cuttings concentration. However, at low annular velocity, the cuttings concentration for the inclined (45-degree) annulus is found to be higher than the horizontal one due to the sliding motion of cuttings on the lower section of the annulus. Overall, the drill pipe rotation has little effect on decreasing the cuttings concentration, but the effect is more pronounced at low annular velocity.

Inhibition of the polymer grafted with dopamine derivatives on hydration and swelling of clay

Swelling of clay minerals is one of the main factors restricting the efficient exploration and development of shale oil and gas. To solve this issue, the free radical induction method was employed to synthesize a polymer grafted with dopamine derivatives, P(AM-DA). This study aimed to evaluate the inhibitory properties of P(AM-DA) on the hydration and swelling of clay and analyze its mechanism. Firstly, P(AM-DA) was characterized by FTIR, HNMR, and TGA. Subsequently, anti-swelling, anti-disintegration, and immersion tests were conducted to evaluate its inhibitory properties. Then, the inhibitory mechanism was further elucidated through Zeta potential tests, particle size analysis, XRD tests, and SEM analysis. Finally, the properties of P(AM-DA) on mud rheology and fluid loss were evaluated. The experimental results showed that the dopamine derivatives were successfully grafted onto the polymer's side chains. Additionally, the result of TGA demonstrated the polymer's good thermal stability below 200℃. P(AM-DA) showed a superior inhibitory effect, and the swelling rate of cores was much lower than that of KCl and polyetheramine. Despite the clay mineral content of shale cuttings being as high as 51.1 %, the anti-disintegration rate could be increased by 66.45 %. The Na-BT core retained its shape and structural integrity after 72-hours immersion, and it could support a weight of 200 g. Regarding the inhibitory mechanism, P(AM-DA) could adsorb onto the surface of clay particles through hydrogen bonding and electrostatic interaction, which reduced the dispersion of clay particles. The protonated amine groups could neutralize the electronegativity of the clay particles, reducing the electrostatic repulsion between the layers. Besides, P(AM-DA) exhibited a series of special behaviors, such as adsorption on the core surface to form a homogeneous layer and insertion into the crystal layer of clay. Both of these behaviors could decrease the passage of water molecules, and the intercalation behavior could also reduce and stabilize the interlayer spacing. In addition, P(AM-DA) could dramatically increase the viscosity of the fluid at higher concentrations and unexpectedly reduce fluid loss. In conclusion, P(AM-DA) showed considerable promise in inhibiting hydration and swelling of clay.

CFD analysis of the full-scale resistance of an oil tanker in presence of a mud–water interface

The presence of mud layers on the bottom of ports and waterways can have negative effects on the hydrodynamic behaviour of marine vessels. This numerical study investigates the effect of muddy seabeds on the full-scale resistance of an oil tanker sailing straight ahead. The objective is to determine the influence of factors such as the densimetric Froude number, UKC and mud rheology at speeds between 3 and 9 knots. The numerical study is conducted using a finite-volume Reynolds-Averaged Navier–Stokes (RANS) flow solver combined with the Volume-Of-Fluid (VOF) method to capture the mud–water interface. At certain critical speeds, the presence of mud increased the ship’s total resistance by up to 15 times compared to the case with solid bottoms. The non-Newtonian rheology of mud was found to influence the ship’s resistance mainly at low speeds and when sailing through the mud layer. This article also shows that, when sailing through mud, the computed resistance at high speeds may be underestimated because of two effects, namely ‘water lubrication’ and ‘numerical ventilation’.

Evaluating Filtration and Thermal Stability of Water-Based Mud Using Green Synthesized Zinc Oxide Nanoparticles

Nanoparticles (NPs) have unique capabilities that make them an eye-opener opportunity for the upstream oil industry. Their nano-size allows them to flow within reservoir rocks without the fear of retention between micro-sized pores. Incorporating NPs with drilling and completion fluids has proved to be an effective additive that improves various properties such as mud rheology, filtration, thermal conductivity, and wellbore stability. However, the biodegradability of drilling fluid chemicals is becoming a global issue as the discharged wetted cuttings raise toxicity concerns and environmental hazards. Therefore, it is urged to utilize chemicals that tend to break down and susceptible to biodegradation. This research presents the practical application of bio-based Zinc Oxide nanoparticles (ZnO NPs) prepared chemically from celery leaf plant extract as green additive in water-based mud drilling fluid (WBM). The study aimed to evaluate the filtration and thermal stability of WBM using green-synthesized ZnO NPs. The results showed that the ZnO NPs have minimal effect of mud density, but significant improvement in mud thermal stability and filtration properties were attained with concentrations lower than 1g. The fluid loss rate was reduced by 33% with 0.45g of ZnO nanoparticles, and the thinnest mud cake was obtained as well. In terms of thermal stability, the bio-based ZnO NPs greatly enhanced the rheological properties of WBM at elevated temperatures. The rate of increment in plastic viscosity (PV) or decrement in yield point (YP) and gel strength occurred in a controllable manner compared to the rheological properties of base mud at high temperatures reaching 90°C. This study provides insight into the effect of green-synthesized ZnO nanoparticles on the performance of water-based mud and highlights their potential as an effective and environmentally friendly additive for the oil and gas industry.

Mathematical modelling of drilling mud plastic viscosity at downhole conditions using multivariate adaptive regression splines

Viscosity is an essential mud property which enables it to transport cuttings out of a well. Determining the real time value of mud viscosity at downhole conditions is complex and till date lacks a precise model. Literature is filled with models that are only applicable at surface conditions with most of the models being artificial neural network (ANN) based. Neural networks have been criticized for their long training time because they rely on a trial-and-error approach to determine their optimal architecture. The few models related to mud viscosity at downhole conditions are based on non-linear regression which are not flexible in nature. However, Multivariate Adaptive Regression Splines (MARS) has at no time been used notwithstanding some of its known benefits over ANN and other regression methods. The focus of this study is to model mud plastic viscosity at downhole conditions with the MARS method using parameters such as temperature, pressure and initial mud viscosity. MARS is a flexible non-parametric splines-based technique that extends linear regression models by including nonlinearities and interactions between predictors. An experimental database comprising 88 and 149 data points culled from literature for oil-based mud (OBM) and water-based mud (WBM) respectively were utilized for developing the models. For each mud type, the most suitable model was determined by choosing the model with the maximum coefficient of determination (R2) value and the least values of mean square error (MSE), root mean square error (RMSE), and generalized cross-validation criterion (GCV). Using these criteria, the R2, MSE and RMSE of the MARS models according to the mud type were found to be 0.64, 104.35, 10.21 and 0.71, 12.8, 3.57 for OBM and WBM respectively while the GCV values were 129.3 and 14.38 for OBM and WBM respectively. Due to lack of mud rheology data at downhole conditions, it was difficult to compare the performance of the developed models with existing models. Parametric importance analysis indicate that temperature has the highest effect on mud viscosity estimation at downhole conditions. The developed models are valid for 20 °C ≤ Temperature ≤315 °C and 0 psi ≤ Pressure ≤40,000 psi. This pioneer work on using MARS in drilling fluid property prediction points out the implementation protocol, the dataset utilized, the relative importance of input variables and the explicit model for estimating mud viscosity at downhole conditions.

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.

Revolutionizing shale drilling with potassium chloride-based natural deep eutectic solvent as an additive

Shale instability is a significant problem, accounting for approximately 70% of wellbore challenges during drilling operations. To address this issue, shale inhibitors are commonly added to drilling mud to stabilize the encountered shale formations. Ionic liquids and deep eutectic solvents have been recognized as effective shale inhibitors due to their environmental friendliness and effectiveness. However, despite their advantages, these solutions still lack full environmental sustainability, leading researchers to explore more natural alternatives like Natural Deep Eutectic Solvents (NADES). This study focuses on the synthesis and application of a NADES composed of Potassium Chloride (KCl) and glycerine, aiming to enhance the environmental profile and efficacy of shale inhibitors. The NADES was prepared with a 1:8 molar ratio at a temperature of 60 °C. Characterization analyses, including Fourier Transform Infrared and Thermogravimetric Analysis, confirmed the formation of bonds between –(OH) and Cl− and demonstrated the NADES's thermal stability up to 200 °C. Incorporating 3% NADES into water-based mud, prepared following API 13B-1 standards, resulted in significant improvements in mud rheology. Specifically, the addition of 3% NADES reduced filtrate volume by 14.2% and mud cake thickness by 19.2%. Furthermore, the 3% NADES exhibited remarkable inhibition of clay swelling by 69.23% and demonstrated a shale recovery rate of 58%. When compared with 3% KCl and 3% 1-ethyl-3-methylimidazolium chloride (EMIM-Cl), the NADES-based mud outperformed both in terms of efficacy. These findings were further supported by additional analyses, including d-spacing measurements (XRD), Zeta Potential, Surface tension, and Field Emission Scanning Electron Microscopy. Additionally, the rheological behavior of the NADES-based mud aligned with the Yield Power Law at both 25 °C and 100 °C. The study's findings contribute to the advancement of greener drilling practices and highlight the applicability of KCl-based NADES as a potential drilling fluid additive.

Eco-Friendly Drilling Fluid: Calcium Chloride-Based Natural Deep Eutectic Solvent (NADES) as an All-Rounder Additive

Designing an effective drilling mud is a critical aspect of the drilling process. A well-designed drilling mud should not only provide efficient mud hydraulics but also fulfill three important functions: enhancing mud rheology, inhibiting hydrate formation in deepwater drilling, and suppressing shale swelling when drilling through shale formations. Achieving these functions often requires the use of various additives, but these additives are often expensive, non-biodegradable, and have significant environmental impacts. To address these concerns, researchers have explored the potential applications of ionic liquids and deep eutectic solvents in drilling mud design, which have shown promising results. However, an even more environmentally friendly alternative has emerged in the form of natural deep eutectic solvents (NADES). This research focuses on an in-house-prepared NADES based on calcium chloride and glycerine, with a ratio of 1:4, prepared at 60 °C, and utilizes it as a drilling mud additive following the API 13 B-1 standards and checks its candidacy as a rheology modifier, hydrates, and shale inhibitor. The findings of the study demonstrate that the NADES-based mud significantly improves the overall yield point to plastic viscosity ratio (YP/PV) of the mud, provides good gel strength, and inhibits hydrate formation by up to 80%. Additionally, it has shown an impressive 62.8% inhibition of shale swelling while allowing for 84.1% improved shale recovery. Moreover, the NADES-based mud exhibits a 28% and 25% reduction in mud filtrate and mud cake thickness, respectively, which is further supported by the results of XRD, zeta potential, and surface tension. Based on these positive outcomes, the calcium chloride–glycerine NADES-based mud is recommended as a versatile drilling mud additive suitable for various industrial applications. Furthermore, it presents a more environmentally friendly option compared to traditional additives, addressing concerns about cost, biodegradability, and environmental impact in the drilling process for an ultimate global impact.

Rheological and filtration control performance of water-based drilling muds at different temperatures and salt contaminants using surfactant-assisted novel nanohydroxyapatite

Today, the high-performance rheological and filtration properties of nanosized particles (NPs) in water-based muds (WBMs) are continuously reported. Nevertheless, NP's properties performance at different temperatures and salt environments, specifically the salt-screening process, needs additional knowledge. Hence, this study developed a WBM system using sodium dodecyl sulfate (SDS)-assisted nanohydroxyapatite (Nano-HAp) for different temperatures and salt contaminants. The impacts of the newly-produced Nano-HAp on the density, pH, rheology, and filtration characteristics of WBM at 298 K and 353 K were examined. The effects of salt cations (Ca2+/Na+) on a bentonite-based suspension (BN-WBM) at 298 K and 393 K and SDS-aided Nano-HAp as a salt-tolerant ingredient in drilling muds were also examined. The Herschel-Buckley and Power law models best described SDS-aided Nano-HAp drilling mud's rheology at 298 K and 353 K, respectively. Nano-HAp improved the rheological and filtration capabilities in salt and water solutions at 298 K, 353 K, and 393 K, making it a perfect field additive. 1.0 g of SDS-aided Nano-HAp is recommended, and it is thermally very stable, according to the thermal gravimetric analysis findings. It increased the viscosity performance by 78.6% at 298 K and by 79.2% at 353 K, provided desirable shear stress between 1.0 and 1000 s−1 shear rates, and decreased the fluid loss by 31.8% (≤ 8 mL) at 298 K and 25% (≤ 11 mL) at 353 K. In BN-WBM, it decreased the viscosity of the BN-salt solution from a 35-fold increase to less than a 5-fold increase and made the BN-based suspension less salt-reliant. It operated by attaching to the BN platelets' positive edge and negative face surfaces, shielding Ca2+/Na+ cations from the BN's ion-susceptible regions to decrease the viscosity and filtration of the BN-based suspension. This study demonstrates the possible use of Nano-HAp particles as effective filtration and rheological control additives in WBMs. It further demonstrates that Nano-HAp was appropriate for enhancing the drilling performance of BN-WBMs while increasing their resistance to salt cation contamination.

Qualitative Analysis of Drilling Fluid Loss Through Naturally-Fractured Reservoirs

Summary Drilling becomes extremely challenging when dealing with naturally fractured reservoirs (NFR). A comprehensive solution is developed in this study to perform qualitative analysis on drilling fluid loss rate and volume to examine how they can be affected by NFR characteristics, drilling fluid rheology, leakoff phenomenon, and wellbore condition. In this regard, the solution is applied to generate type curves to facilitate the sensitivity analysis (refer to the provided Supplementary Materials). The presented solution accounts for not only drilling fluid pseudoplasticity in the total system but also matrix medium under wellbore constant pressure assumption (by including dimensionless matrix contribution parameter). It is also able to measure mud loss advancement not only through NFR but also through homogeneous reservoirs. The developed solution is validated by reducing it to the preexisting solution (designed for Newtonian fluid case) by incorporating assumptions into it. The result demonstrates the significance of NFR properties and drilling fluid pseudoplasticity on the leakoff phenomenon and total loss volume, especially when constant pressure is established inside the wellbore. The finding reveals that three periods can be identified through generated type curves depending on NFR characteristics, drilling fluid rheology, and leakoff coefficient. Therefore, different drilling fluids with specific pseudoplasticity should be used in each period to mitigate drilling fluid loss effectively. In this regard, the study is supposed to design drilling fluid in a way to maintain its pseudoplasticity at a higher level at early and late times, while being maintained at a lower level during the transient period, a critical aspect for managed pressure drilling techniques, particularly in the context of dual-gradient drilling applications. Additionally, a procedure should be implemented to lessen the transient period while attempting to keep drilling fluid advancement occurrence at a lower rate, which shows that drilling fluid pseudoplasticity can be used as an effective tool to manage this period. The obtained result also indicates that the importance of drilling fluid rheology to control total loss volume is greater for NFR with higher leakoff than with lower leakoff. Furthermore, the greater the differential pressure inside the wellbore, the greater the importance of mud rheology to reduce drilling fluid loss. The outcome of the study not only facilitated qualitative and quantitative analyses through NFR but also enabled decision-makers to instantaneously select optimal wellbore conditions and drilling fluid pseudoplasticity.

Rheology and lubricity characteristics study at different temperatures using synthesized SnO2 nanoparticles in KCl free bentonite water base mud

Drilling mud is a major concerning element due to its high operational and economic impact on the drilling process. Various additives are introduced to enhance the efficiency of drilling fluid, but none of them could perfectly achieve their proposed efficacy in drilling operations. Researchers conceived several nanoparticles (NPs) in drilling fluid to dissolve this issue. In a singular instance, commercial tin oxide (SnO2) nanoparticles were utilized to analyze the influence of NPs on the rheological and filtration properties of inorganic KCl salt-based drilling fluid. However, the effect of SnO2 NPs on mud lubricity characteristics is not studied previously. However, due to the hazardous behavior of KCl, its use is very limited. Thus, we consider a KCl-free bentonite water-based mud to avoid any environmental damages from drilling operations. We also use SnO2 NPs that is synthesized in our laboratory by co-precipitation method. In addition to rheological and filtration properties, we also investigate the effect of NPs on mud's lubricity that was not considered in the previous study. Drilling fluid properties are measured at five different NPs concentrations of 0.10, 0.25, 0.50, 0.75 & 1.0 wt%, and at six different temperatures of 30, 40, 50, 60, 70, and 80 °C, while filtration properties are measured using API low-pressure low temperature (LPLT) condition. The addition of 0.1 wt% SnO2 NPs increases plastic viscosity, yield point, 10 s gel strength, and 10 min gel strength by 10%, 63%, 20%, and 14%, respectively. The maximum reduction in lubricity coefficient is found to be 14% at NPs concentration of 1.0 wt%. The NPs concentration of 0.5 wt% yielded a reduction in fluid loss and mud cake thickness by 8.1% and 34%, respectively. The study suggests that SnO2 NPs can be employed as an additive to improve the rheology, lubricity, and filtration properties of KCl-free bentonite water-based drilling mud.

Evaluations of Polyacrylamide Water-Based Drilling Fluids for Horizontal Drilling in the Shaly Wolfcamp Formation

Summary The Permian Basin, located in southeastern New Mexico and west Texas, is treated as the largest province of oil and gas production in the United States (US). The majority of hydrocarbon production from the Permian Basin is from the Wolfcamp shaly formation. Drilling horizontal and extended reached wells is continuously increasing day after day in the Permian Basin. Oil-based mud (OBM) is used to drill these horizontal wells for enhancing shale inhibition, reducing torque and drag, and supporting thermal stability of mud rheology. Due to environmental regulation for limiting use of OBM, the petroleum industry has tried to develop water-based fluid (WBF) that approaches the performance advantages of OBM. The main objective of this research is to formulate and develop WBF by using polyacrylamide anionic friction reducer (AFR) for drilling the lateral sections of horizontal wells in the shaly Wolfcamp formation. Shale inhibition, barite sagging, lubricity, and thermal stability of the formulated WBF with AFR will be studied to evaluate the developed WBF. Laboratory experiments were conducted to develop and evaluate the performance of the formulated WBF with AFR. The shale inhibition capabilities of the developed WBF with AFR were evaluated by using zeta potential, shale dispersion test, and immersion test. The results prove the capability of the formulated WBF with AFR to prevent both shale swelling and shale dispersion. AFR limits water penetrations to shale through encapsulation. The mixing procedures of AFR with WBF affect both the thermal stability of mud rheology and shale inhibition. Adding AFR to WBF helps to suspend weighting materials and mitigate barite sag. Besides, AFR decreases torque and drag by decreasing the coefficient of friction (COF). Furthermore, AFR supports enhanced stability of mud rheology with time up to 14 days at temperatures up to 180°F. The formulated WBF with AFR can be used for enhancing shale inhibition, supporting thermal and time stability of fluid rheology, improving lubricity, and minimizing barite sagging for drilling shaly Wolfcamp formations. This study presents a promising WBF to replace OBM to drill lateral sections in the Permian Basin.

Enhancing drilling mud performance through CMITS-modified formulations: rheological insights and performance optimization.

In the context of deep well drilling, the addition of functionalized additives into mud systems becomes imperative due to the adverse impact of elevated borehole temperatures and salts on conventional additives, causing them to compromise their intrinsic functionalities. Numerous biomaterials have undergone modifications and have been evaluated in drilling muds. However, the addition of dually modified tapioca starch in bentonite-free mud systems remains a notable gap within the existing literature. This study aims to examine the performance of dually modified carboxymethyl irradiated tapioca starch (CMITS) under high temperature and salt-containing conditions employing central composite design approach; the study evaluates the modified starch's impact on mud rheology, thermal stability, and salt resistance. The findings indicated that higher DS (0.66) and CMITS concentrations (8 ppb) improved plastic viscosity (PV), yield point (YP) and gel strength (GS), while increased salt and temperature decreased it, demonstrating the complex interplay of these factors on mud rheology. The developed empirical models suggested that DS 0.66 starch addition enhanced rheology, especially at elevated temperatures, demonstrating improved borehole cleaning potential, supported by quadratic model performance indicators in line with American Petroleum Institute (API) ranges. The optimized samples showed a non-Newtonian behavior, and Power-law model fitting yields promising results for improved cuttings transportation with starch additives.

Selection of an Optimum Drilling Fluid Model to Enhance Mud Hydraulic System Using Neural Networks in Iraqi Oil Field

In drilling processes, the rheological properties pointed to the nature of the run-off and the composition of the drilling mud. Drilling mud performance can be assessed for solving the problems of the hole cleaning, fluid management, and hydraulics controls. The rheology factors are typically termed through the following parameters: Yield Point (Yp) and Plastic Viscosity (μp). The relation of (YP/ μp) is used for measuring of levelling for flow. High YP/ μp percentages are responsible for well cuttings transportation through laminar flow. The adequate values of (YP/ μp) are between 0 to 1 for the rheological models which used in drilling. This is what appeared in most of the models that were used in this study. The pressure loss is a gathering of numerous issues for example rheology of mud), flow regime and the well geometry. An artificial neural network (ANN) that used in this effort is an accurate or computational model stimulated by using JMP software. The aim of this study is to find out the effect of rheological models on the hydraulic system and to use the artificial neural network to simulate the parameters that were used as emotional parameters and then find an equation containing the parameters μp, Yp and P Yp/ μp to calculate the pressure losses in a hydraulic system. Data for 7 intermediate casing wells with 12.25" hole size and 95/8" intermediate casing size are taken from the southern Iraq field used for the above purpose. Then compare the result with common equations used to calculate pressure losses in a hydraulic system. Also, we calculate the optimum flow by the maximum impact force method and then offset in Equation obtained by (Joint Marketing Program) JMP software. Finally, the equation that was found to calculate pressure losses instead of using common hydraulic equations with long calculations gave very close results with less calculation.

Designing Smart drilling fluids using modified nano silica to improve drilling operations in Geothermal wells

High pressure and high temperature (HPHT) conditions in geothermal wells have necessitated the need to develop thermally stable geothermal drilling mud systems to combat potential drilling complications. This is because mud fluids degrade under HPHT conditions due to high temperature effects. This study therefore aims to establish the optimum concentration of a cationic surfactant that would successfully modify the surface of silica nanoparticles and thereafter, evaluate the performance of modified nano silica as a rheological and filtration property enhancer in water-based muds (WBMs). The surface of silica nanoparticle was successfully modified by adding Hexadecyltrimethylammonium bromide (CTAB) to silica solution. Different mud formulations containing modified nano silica with varying zeta potential values, SNP3 -S2, SNP3 -S4, SNP3 -S5, SNP3 -S6, and SNP3 -S7 with -17.7 mV, 20 mV, 28.2 mV, 35.4 mV, and 37.1 mV respectively were investigated. Results showed that modified nano silica with the highest absolute value of zeta potential enhanced drilling mud rheology as temperature increased from 149°C to 232 °C. The optimal amount of CTAB was found to be between 1.0 and 2.0 wt.%. Filtration loss was reduced by 11.4, 17.6, and 29.5% on average for mud samples SNP3-S5, SNP3-S6, and SNP3-S7, respectively, at all temperatures. Mud cake thickness was reduced by 19.9, 11.6, and 28.7% on average by mud samples SNP3-S5, SNP3-S6, and SNP3-S7 respectively at all temperatures.