Performance Of Drilling Fluids Research Articles

Improving the performance of water-based drilling fluid using amino acid-modified graphene oxide nanocomposite as a promising additive

It is possible to take advantage of nanomaterials' properties to improve water-based drilling fluids' flux and physical properties. In this paper, glycine methyl ester hydrochloride was synthesized, and the chemical structure was verified to be used as a surface modifier of graphene oxide. At the same time, graphene oxide was prepared from graphite and chlorinated with thionyl chloride, and a nucleophilic substitution reaction was performed to increase the hydrophilicity of graphene oxide. FTIR, Raman, HRTEM, and XRD techniques have identified the prepared and obtained materials from chlorinated graphene oxide's reaction with glycine methyl ester hydrochloride. The glycine-modified graphene oxide (GO) was evaluated as drilling-fluid additives at different concentrations (2.66%, 5.32%, and 10.64%) to enhancement the thermal stability of water-based drilling fluid and reducing the filtration loss. The obtained results confirmed that the successful glycine-modified graphene oxide/bentonite to enhance both thermal stability (up to 350 °F) and filtration loss.

Thermo-associating copolymer based on cross-Linked 2-acrylamido-methylpropane sulfonic acid, part C: Experimental study into the performance of deepwater aqueous drilling fluids

In deepwater drilling, aqueous drilling fluid (ADF) is meaningful because it could be a potential alternative to non-aqueous drilling fluid (NADF). However, its rheological properties varies notably over a broad range of temperature, driving technical hazards including equivalent circulating densities control and lost circulation. Reducing the temperature dependence of the rheololgical properties of ADF thus is a crucial step towards achieving successful and cost-effective deepwater drilling operation. Herein, the combination of clay particles and new class of thermo-associating copolymer, CGBA which was reported in our previous works was exploited to conquer this issue due to their distinct inherent properties. In detail, the contribution of CGBA in driving viscosity enhancement macroscopically in aqueous solution and slurry across a temperature range of 4–170℃was preliminary evaluated by viscosity measurement, zeta potential measurement, and differential scanning calorimetry (DSC). Results from rheological test indicated that, CGBA showed remarkable thermo-thickening phenomenon in slurry ascribed to the self-assemble of BA side-arms. The absolute value of the zeta potential of CGBA aqueous solution increased in slurry. DSC experiments showed that, albeit CGBA in aqueous solution and slurry displayed similar endotherms process, both phase transition and heats of transition decreased from 62 to 43 ℃ and 2.13 to 1.71 kJ/mol DEAm, respectively in slurry. The thermo-rheological properties dependence of the aged CGBA containing drilling fluid was further examined across the temperature range of 4−75 ℃ following the American Petroleum Institute (API) procedure. Results clearly indicated that the designed FR-ADF delivers more stable rheology than those of typical ADF. The change rate of key rheological parameters of the designed FR-ADF, such as, plastic viscosity (PV), yield point (YP) and low shear rate viscosity (LSRV) were less than 30 %. Additionally, the laboratory contamination tests indicated that the designed FR-ADF was found to possess good inhibition properties as well as strong tolerance to the contamination of salts. Albeit the contamination to mudstone cuttings impacted the fluid rheology, the change rate was within an acceptable range. In comparison with reported FR-NADF, the designed FR-ADF showed great potential for application in deepwater drilling operations. This work introduces for the first time a N,N’-diethylacrylamide-based sticker as a novel rheological modifier in deepwater ADF to further broaden the established theory of thermo-associating copolymer in deepwater ADF.

Experimental Investigation of Inhibitive Drilling Fluids Performance: Case Studies from United States Shale Basins

Shale formations are attractive prospects due to their potential in oil and gas production. Some of the largest shale formations in the mainland US, such as the Tuscaloosa Marine Shale (TMS), have reserves estimated to be around 7 billion barrels. Despite their huge potential, shale formations present major concerns for drilling operators. These prospects have unique challenges because of all their alteration and incompatibility issues with drilling and completion fluids. Most shale formations undergo numerous chemical and physical alterations, making their interaction with the drilling and completion fluid systems very complex to understand. In this study, a high-pressure, high-temperature (HPHT) drilling simulator was used to mimic real time drilling operations to investigate the performance of inhibitive drilling fluid systems in two major shale formations (Eagle Ford Shale and Tuscaloosa Marine Shale). A series of drilling experiments using the drilling simulator and clay swelling tests were conducted to evaluate the drilling performance of the KCl drilling fluid and cesium formate brine systems and their effectiveness in minimizing drilling concerns. Cylindrical cores were used to mimic vertical wellbores. It was found that the inhibitive muds systems (KCl and cesium formate) provided improved drilling performance compared to conventional fluid systems. Among the inhibitive systems, the cesium formate brine showed the best drilling performances due to its low swelling rate and improved drilling performance.

Experimental study on the influence of coal powders on the performance of water-based polymer drilling fluid

Coal powders, as cuttings, invade the drilling fluid along a coal seam during coalbed methane development, thereby changing the properties of the drilling fluid. Therefore, this work aims to investigate the influence of coal powders on drilling fluid performance. The powders of lignite, anthracite, and contrasting shale were added to a water-based polymer drilling fluid. Then, the rheology, filtration, lubricity, and adhesiveness were measured, and the natural degradation, as well as the wettability were further evaluated. The results show that some parameters of the drilling fluid, including viscosity, lubrication coefficient, adhesion coefficient, contact angle, and surface tension, increase after adding coal powders, while other parameters, such as filtration loss and natural degradation, decrease. Compared with lignite and shale, anthracite powders, with the lowest mineral content, exhibit the smallest change in the rheological property, lubricity, adhesion, and natural degradation of the drilling fluid. Moreover, the content and size of the coal powders generally have opposing effects on the drilling fluid. When the coal powder content reaches 3 wt.%, the surface tension and contact angle of the drilling fluid show more evident changes than other parameters. Based on the analysis of the stress intensity factor, the drilling fluid with coal powders exceeding 100 mesh can reduce the capillary force in microfractures, and in combination with other factors (such as reduced filtration loss and sealing and supporting of the microfractures), improves wellbore stability. Therefore, coal powders with suitable particle sizes and concentration levels are expected to become a new drilling fluid material to protect coal field reservoirs.

A field study, laboratory test and cost estimation of solid and liquid lubricants in directional wells to reduce friction coefficient and improve ROP

Drilling fluid is being used to facilitate drilling operation from the surface to a target formation. Due to the complexity of well geometry in directional drilling operations and high torque and drag forces, minimizing the coefficient of friction (CoF) is important. Excessive torque and axial drag cause mechanical erosion on the drill string, which ultimately leads to fatigue, wash out and twist off. Field data for 9 wells in one of the Iranian oilfields showed that slide drilling was practically impossible beyond 4000 m due to the unexpected high torque and drag during directional drilling despite the presence of liquid lubricants in drilling fluid at concentrations up to 5 vol% as per drilling program. Based on the results, the primary source of torque and drag in the wells with proper hole conditioning is sliding friction. Using different types of lubricant in drilling fluid system is the most practical methods to reduce the drag force (sliding friction) caused by the contact between drillstring and well casing or borehole. This paper investigates the effect of solid and liquid lubricants on the CoF in laboratory and field applications. Based on the successful implementation, a specific instruction was designed for the use of glass bead as a solid lubricant in drilling fluid to reduce the CoF. Cost estimation indicates that compared to the liquid lubricants, solid lubricants can reduce drilling fluid costs significantly. Moreover, based on Experimental results, no more than 5–6 percent of liquid lubricants can be used to reduce friction coefficient. This limitation, along with the issue of lubrication regimes, leads us to use solid lubricants. Laboratory and field test results showed that addition of glass bead as a solid lubricant can improve the performance of water-based drilling fluids as evidenced by improvement in ROP up to 240% (average ROP: 160%).

Research of self-adaptive PID drilling fluid level control algorithm based on differential flow

Aimed at the puzzle of traditional PID control algorithm not satisfy level control requirement when drilling fluid performance changing, the article proposed adaptive PID level control algorithm based on differential flow. Through monitoring differential flow between slurry pump outlet and buffer pry inlet, the algorithm got optimized PID control parameters and evaluated drilling fluid properties, which could be used for liquid level control under different fluid medium characteristics. In the laboratory test of drilling fluid tank, the proposed algorithm could always keep the level deviation within 5% through self-adaptive modify PID control parameters under different drilling fluid characteristics. The results shows that the algorithm has wide adaptability and high reliability, and can be applied to the liquid level control situation where the characteristics of the fluid medium change.

Smart Solutions for Oil and Gas industry Challenges

Crude oil is the most attractive source of energy. It is formed at high temperatures and pressures deep down in the earth. Extraction of this energy resource involves expensive drilling and extraction processes. The composition and physical characteristics of the oil depend on the source of the organic material, temperature, and heat. The greater the viscosity of the oil the more difficult it is to extract. Heavy oil, is the name given to oil with API gravity between 10 and 20, and high viscosity <10,000 cP. It is technologically challenging and expensive to extract. Many solutions have been explored owing to the high financial returns in this business. In this study, we propose new smart solutions, utilizing unique properties of nanoparticles of different shapes and sizes to reduce the viscosity of heavy oil to make it easier to extract. Nanoparticles are 1- 100nm in size, have a high surface-to-volume ratio, high heat capacity, excellent heat conductivity, low thermal expansion, and high melting temperatures. A combination of some of these properties was utilized to explore solutions for drilling and heavy oil viscosity problems. In drilling, problems like pipe sticking lost fluid circulation, formation damage, erosion of the borehole, thermal instability of drilling fluids, and their insufficient gel properties, lie in controlling and optimizing the rheology of the drilling fluid. Therefore, to advance the performance of water-based drilling fluids in such harsh reservoir conditions, a simple treatment based on nanotechnology was utilized by synthesizing in-house nano-additives. 1-3 wt% of nano-additives increases fluid density by~5% and dynamic viscosity by-20% and reduces fluid loss by 50%. In addition to this, it forms a thin smooth Mud Cake with the surroundings of the formation. At ambient temperatures, crude oil and bitumen are resistant to flow through reservoir rock because of their high viscosities. Consequently, the energy expended to produce and upgrade a barrel of oil can be as high as 40% of the total energy available from the crude oil resource. Thermally enhanced oil recovery techniques such as steam-assisted recovery and also in situ combustions are employed to upgrade and save the physicochemical properties of the oil. All these recovery techniques are expensive, complicated, and need periodic maintenance; therefore, direct and cheap solutions are the main targets for high in situ upgrading. Our study provides an alternative method that can help in the production and upgrading of such heavy oil by cracking it. For the heavy oil cracking process, iron oxide Nano-Rods (IONRs) were synthesized by an environmentally friendly method. These rods were embedded and well mixed with 1 L of heavy oil (12 API) and subjected to direct microwave radiation. The radiation causes a reduction in the dynamic viscosity of crude oil due to the presence of dipole water molecules. This reduction increased up to 50% when a controlled amount of IONRs additives were added at the same temperature.

Calculation of safe drilling mud density window for shale formation by considering chemo-poro-mechanical coupling effect

Abstract It is difficult to define safe drilling mud density window for shale sections. To solve this problem, the general Biot effective stress principle developed by Heidug and Wong was modified. The Weibull statistical model was used to characterize the hydration strain-related strength damage. Considering drilling fluid sealing barrier on shale, a calculation method of safe drilling mud density has been established for shale formation under drilling fluid sealing-inhibition-reverse osmosis effect, combined with a flow-diffusion coupling model. The influence of drilling fluid sealing and inhibiting parameters on safe drilling mud density window was analyzed. The study shows that enhancing drilling fluid sealing performance can reduce the pore pressure transmission and solute diffusion; the inhibiting performance of drilling fluid, especially inhibition to strength damage, is crucial for the wellbore collapse pressure of shale section with significant hydration property. The improvement of drilling fluid sealing and inhibition performance can lower collapse pressure and enhance fracturing pressure, and thus making the safe drilling fluid density window wider and the collapse period of wellbore longer. If there is osmosis flow in shale, induced osmosis flow can make the gap between collapse pressure and fracturing pressure wider, and the stronger the sealing ability of drilling fluid, the wider the gap will be. The safe drilling mud density window calculation method can analyze the relationships between collapse pressure, fracturing pressure and drilling fluid anti collapse performance, and can be used to optimize drilling fluid performance.

Study on the viability of egg shell as a lost circulation material in synthetic based drilling fluid

Lost circulation is one of the most severe issues in drilling operation which can cause fracture formation or be induced during drilling activities. These scenarios make it imperative to design the drilling fluid in a minimal invasion of the fluid that occur in the formation along with assist in strengthening the wellbore condition. To solve this problem, Lost Circulation Materials (LCM) are required which is expected to bridge and seal the fractures. As the contemporary worldwide development towards environment friendly, technical ability and cost-effectiveness, hence the viability of Egg Shells as LCM are being investigated since the daily disposal waste is rich in Calcium Carbonate (CaCO3) compound. In addition, the effect of egg shell particle size distribution on the drilling fluid performance was also study. The performance of egg shells was compared with the industry standard-sized CaCO3 in term of its rheology properties, fluid loss, fluid invasion, and lubrication ability. The rheology properties result shows a stable reading while for High Pressure High Temperature (HPHT) filter press test, the drilling fluids performance showed the same mud cake thickness of 1/32 but slightly different in fluid loss. The drilling fluids also has a minimal invasion on Sand Bed Test (SBT) with lubrications coefficient of 0.0753. From this study, it is found that egg shells can function effectively as LCM additives, the same as the standard CaCO3 used in the industry.

Laboratory optimization on performance of high density brine-based drilling fluid

The brine-based drilling fluid is paramount for drilling operation in the salt-anhydrite formations. In this work, a novel high density brine-based drilling fluid was designed and established, based on the features of salt-anhydrite formation in Missan Oilfields. A suite of laboratory tests has been carried out to comparatively evaluate effect of key additive amounts on standard properties of drilling fluids. The formula of the high density brine-based drilling fluid was optimized. The newly developed brine-based drilling fluid possesses excellent rheology, filtrate, thermal stabilization, inhibition and lubricity properties, which can provide an alternative to drilling through the salt-anhydrite formation in Missan Oilfields.

Prevention of Barite Sag in Oil-Based Drilling Fluids Using a Mixture of Barite and Ilmenite as Weighting Material

Drilling high-pressure high-temperature (HPHT) wells requires a special fluid formulation that is capable of controlling the high pressure and is stable under the high downhole temperature. Barite-weighted fluids are common for such purpose because of the good properties of barite, its low cost, and its availability. However, solids settlement is a major problem encountered with this type of fluids, especially at elevated downhole temperatures. This phenomenon is known as barite sag, and it is encountered in vertical and directional wells under static or dynamic conditions leading to serious well control issues. This study aims to evaluate the use of barite-ilmenite mixture as a weighting agent to prevent solids sag in oil-based muds at elevated temperatures. Sag test was conducted under static conditions (vertical and inclined) at 350 °F and under dynamic conditions at 120 °F to determine the optimum ilmenite concentration. Afterward, a complete evaluation of the drilling fluid was performed by monitoring density, electrical stability, rheological and viscoelastic properties, and filtration performance to study the impact of adding ilmenite on drilling fluid performance. The results of this study showed that adding ilmenite reduces sag tendency, and only 40 wt.% ilmenite (from the total weighting material) was adequate to eliminate barite sag under both static and dynamic conditions with a sag factor of around 0.51. Adding ilmenite enhanced the rheological and viscoelastic properties and the suspension of solid particles in the drilling fluid, which confirmed sag test results. Adding ilmenite slightly increased the density of the drilling fluid, with a slight decrease in the electrical stability within the acceptable range of field applications. Moreover, a minor improvement in the filtration performance of the drilling fluid and filter cake sealing properties was observed with the combined weighting agent. The findings of this study provide a practical solution to the barite sag issue in oil-based fluids using a combination of barite and ilmenite powder as a weighting agent to drill HPHT oil and gas wells safely and efficiently with such type of fluids.

Laboratory evaluation to assess the effectiveness of inhibitive nano-water-based drilling fluids for Zubair shale formation

While drilling through shale formations, shale hydration, including shale swelling and dispersion, is frequently reported as the main wellbore instability problems, particularly when conventional drilling fluids (water-based) are used. These problems have many adverse effects on the drilling operations resulting in non-productive time. Nanoparticles have been recently introduced as a unique alternative to improve the performance of water-based drilling fluids for shale applications. This paper presents an experimental evaluation to investigate the effectiveness of an inhibitive nano-water-based drilling fluid in reducing the swelling of Zubair shale formation. Well-preserved core samples, which were retrieved from Zubair formation, were characterized using X-ray diffraction, and X-ray fluoresces to quantify the amount of the swelling minerals. Scanning electron microscopy was used to identify the existence of microfractures within the samples. Three different nano-based drilling fluids containing titanium dioxide (TiO2), copper oxide (CuO), and magnesium oxide (MgO) at two different concentrations (0.5% and 1.5% by vol) were evaluated through a set of tests to assess the shale reactivity in the presence of these nano-based fluids. In addition, the effect of these nanoparticles on the rheological and filtration properties was studied. The results showed that the shale samples contain 41.26% silicon dioxide (SiO2) and 22.73% aluminum oxide (Al2O3), indicating the presence of smectite and illite. Based on the reactivity tests, fluids containing CuO at 1.5% by vol outperformed the other fluids in terms of reducing the reactivity, where the expansion rate was reduced by 82.7% compared to the reference sample submerged in fresh water. In addition, the addition of nanoparticles resulted in reducing the plastic viscosity, increasing both the yield point and gel strength, and reducing the fluid loss under low-pressure low-temperature conditions.

Effect of High Temperature on Rheology and Electrical Stability of Saraline and Smooth Fluid 05 Mud

In drilling operations, drilling mud plays a very important role because it is irreplaceable functions. Drilling activities relate to problems caused by complex conditions in formation due to changes in temperature, pressure, and contamination from formation fluids. Using Oil Base Mud (OBM) mud systems in the form of Saraline and Smooth Fluid 05 is tested for drilling fluid performance and the results can be a reference for drilling operation. This research consist of two parts, the first: determining the drilling mud rheology value in the form of (Plastic Viscosity, Yield Point and Gel Strength) in each drilling mud of Saraline and Smooth fluid 05 mud using various high temperature parameters of 350oF, 300oF, and 270oF. The results of the mud rheology tests show at the higher the temperature, the values of rheology decreases. The second experiment is to determine the level of electrical stability in the mud which functions of oil-wet content in oil sludge (Saraline and Smooth fluid 05). The electrical stability value has a minimum limit value in OBM, which is 500 volts. In this experiment showed that the higher the temperature value, the electrical stability value in the mud will decrease, but in this study the value of electrical stability in Saraline mud and Smooth fluid 05 has a value above 500 volts, the composition OBM of Saraline and Smooth Fluid 05 sludge has very good oilwet content.

Effects of silica nanoparticles on the performance of water-based drilling fluids

In this research, two groups of experiments were conducted to investigate the effects of silica (SiO2) nanoparticles on the filtration and rheological properties of water-based drilling fluids. In the first group, bentonite, chrome-free lignosulfonate (CFL) and carboxymethyl cellulose (CMC) were used in different concentrations to obtain base fluids. Nanofluids were prepared by adding 0.5 g of four different silica nanoparticles into these drilling fluids. Comparison of rheological properties, fluid loss amounts and mud cake thicknesses were performed at two different temperatures (25 °C and 49 °C). It was concluded that all of the nanoparticles reduced the filtration efficiency of bentonite muds. On the contrary, a reduction in fluid loss was observed for some lignosulfonate muds containing nanoparticle. However, no significant change in mud cake thickness and rheological properties was seen for both drilling fluids.Since no positive effect was observed in the first part, further investigation was done with higher bentonite and nanoparticle concentrations than previous experiments. Moreover, only bentonite was used as additive to eliminate other parameters and to see more clearly the effect of nanoparticles in bentonite mud. Samples were formulated with 7% by weight of bentonite and 0.5% and 1.5% by weight of nanoparticles. It was seen that the amount of fluid loss is directly proportional to the nanoparticle concentration. Therefore, Darcy's Law was used to compare the permeability of mud cakes and it was confirmed that nanofluids form permeable mud cakes compared to base fluid.

Gr-Al2O3 Nanoparticles-Based Multifunctional Drilling Fluid

Various chemical additives are used in drilling fluids to improve drilling efficiency and increase oil production. Dispersing nanoparticles as additives in drilling mud is one of the more promising techniques that could help solve many difficulties of drilling operations. However, the existing research in this field is insufficient and suffers from numerous inconsistent outcomes. This study aims to discover and evaluate the impact of graphite-alumina hybrid nanoparticles on the rheology, thermal properties, zeta potential, and electrical conductivity of water-based drilling fluids. This study shows that that the addition of nanoparticles improves the effectiveness of water-based mud (WBM), both in static and dynamic situations due to the establishment of an appropriate gel structure that can be easily broken under low shear stress. Furthermore, these nanoparticles improve the degree and the speed of structural recovery by reducing the relaxation time, which is necessary to avoid the sedimentation of weighting materials and drilled cuttings. Besides, nanoparticle seeded fluid improves the effective thermal conductivity of conventional drilling fluids, and the highly charged suspension resulting from the addition of nanoparticles is desirable for drilling operations. It is also observed that nanoparticles could penetrate through the porous wall of the wellbore and clog the pores, forming a thin and impermeable cake that reduces drilling fluid loss. When properly engineered, nanoparticles could significantly improve the performance of conventional drilling fluids.

The Rheology and Performance of Geothermal Spring Water-Based Drilling Fluids

In this study, the rheological properties and performances of mud prepared with geothermal spring water to be used by geothermal drilling operators were examined at ambient and elevated temperatures. In this context, mud samples were prepared in the compositions detailed in the API specification by using five different geothermal spring water types and a distilled water type. Afterwards, density, apparent viscosity, plastic viscosity, yield point, gel strength, fluid loss, pH, and filter cake thickness of these samples were measured. The drilling muds were analyzed by means of rheological tests in accordance with the standards of the American Petroleum Institute (API). The experimental results have revealed that the mud prepared with geothermal water have lower viscosity and yield point compared to those prepared with freshwater at elevated temperatures. The stability of the muds decreases, especially at temperatures higher than 250°F, and they start to become flocculated. It was concluded that geothermal water-based muds have higher API fluid loss and cake thickness than the freshwater-based one. Therefore, it could be interpreted that the muds prepared with geothermal spring water will exhibit lower flow performance and lower ability of hole cleaning and rate of penetration compared to the freshwater muds. Hence, it is recommended that this kind of water should not be used to prepare drilling mud.

Water-based drilling fluid formulation using silica and graphene nanoparticles for unconventional shale applications

The development of unconventional shales started a new era in the oil and gas industry. These reservoirs represent a challenge to conventional drilling fluids since the fluid invasion, cutting dispersion, or shale swelling can lead to wellbore instability problems. Although oil-based drilling fluids (OBM) are capable to control these issues, environmental and economic concerns limit its application. Recently, nanoparticles (NPs) have introduced a new perspective in drilling fluid technology, offering a unique alternative to improve the performance of water-based drilling fluids (WBM) for shale applications. This research evaluates the potential of using silica nanoparticles (SiO2-NPs) and graphene nanoplatelets (GNPs) to formulate a nanoparticle water-based drilling fluid (NP-WBM). The study considers a bottom-up approach, selecting the NPs based on the Woodford Shale's characterization and focuses its primary objective in finding the most suitable NP combination to enhance the rheological, filtration and inhibition properties of the customized NP-WBM. The shale characterization included X-ray diffraction (XRD), cation exchange capacity (CEC), and scanning electron microscopy (SEM). The zeta-potential technique was used to assess the stability of the NPs. The NP-WBM was evaluated by means of API filtration test (LTLP), high-temperature/high-pressure (HTHP) filtration test and rheological measurements using a conventional viscometer. Finally, the inhibition capability of the NP-WBM was tested against the Woodford shale through immersion and cutting dispersion tests. NPs' characterization revealed that both additives can provide stable suspensions with zeta-potential values < −30 mV. A total NP concentration of 0.75 wt% (0.5 wt% of SiO2-NPs and 0.25 wt% of GNPs) yielded to the maximum reduction in filtrate volume at both, LTLP and HTHP conditions. The less permeable filter cake resulted in no spurt-losses, supporting the NPs' plugging effect. A strong cross-linked network created between the NPs and the conventional additives increased the cutting carrying capacity of the NP-WBM with slight effects on its plastic viscosity (PV). The immersion test carried out in water revealed that illitic shales might experience micro-fractures along the bedding planes in the absence of bridging materials. Contrarily, the NP-WBM provided an adequate plugging network between grain boundaries, resulting in no micro-fractures, and the reduction of the cutting erosion by 35.61%. Overall, this study highlights the capability of nanomaterials to extend the reliability of WBM to harsher environments while seeking an eco-friendlier alternative.

Experimental investigation of hole cleaning in directional drilling by using nano-enhanced water-based drilling fluids

Inadequate hole cleaning often leads to challenges in drilling and well completion operations such as low rates of penetration, pipe sticking, losing tools, difficulties in liner/casing placements, etc. Designing a drilling fluid with improved rheological properties would be a solution to increase cuttings transportation efficiency. This study investigates the performance of nanosilica water-based drilling fluids for the hole cleaning process in directional drilling operations. Different inclination angles have been considered in a flow loop system with different rotational speeds (0 and 150 rpm) to simulate the drilling conditions in a wellbore. The performance of nano-enhanced drilling fluids in the cuttings removal process was compared with conventional water-based drilling fluids, and it was found that silica nanoparticles increased the cuttings transport efficiency in all experiments. The results indicated that the presence of nanosilica in the mud increased the colloidal interactions with cuttings and contributed to the improvements in cuttings transportation efficiency by 30.8–44% for different nano-enhanced water-based drilling fluids used in this study. The implementation of nanosilica in water-based drilling fluids showed promising results in the hole cleaning process which demonstrates the feasibility of using them in extended reach drilling operations.

Research on High Temperature and High Density White Oil Based Drilling Fluid and Its Application in Well 201H7-6

As the depth and horizontal length of shale gas development wells increase, the requirement for the temperature resistance and the ability of the drilling fluids to stabilize the shale formation becomes higher. A new type of high temperature and high density white oil based drilling fluid system has been developed in laboratory. Research shows that the drilling fluid system has good rheological property, low filtration loss, strong anti-debris pollution capability and good plugging performance at high temperature and high density. The system has been successfully applied in the 201H7-6 well. Application results show that the drilling fluid rheology, high temperature and high pressure fluid loss and demulsification voltage meet the field requirements. The drilling fluid performance is stable in drilling an 1800 m horizontal section, and no stuck or shale swelling and wellbore collapsing are induced. It is the first well drilled successfully with domestic white oil-based drilling fluid in Zigong Region. It also sets several new records including the deepest well, the shortest drilling cycle, and the fastest drilling speed in that region, which provides valuable experience for the future drilling activities.

The Research of Polymer Film-Forming Plugging Agent for Drilling Fluid

In order to improve the plugging and anti-collapse performance of water-based drilling fluid, a polymer film-forming plugging agent LWFD is synthesized by emulsion polymerization. The effect of the agent on rheology, API filtration loss, lubricity and film plugging of polymer drilling fluid and cationic drilling fluid is evaluated in laboratory. The experimental results show that the agent has little effect on the rheology and filtration loss of polymer drilling fluid and cationic drilling fluid, and can improve the lubricity of drilling fluid. The synthesized polymer film-forming plugging agent LWFD has good plugging properties for sand discs with different permeabilities, and the agent can effectively improve the film-forming plugging and temperature resistance of drilling fluid when combined with the inorganic nano-plugging agent NMFD. The high performance polymer drilling fluid formed by introducing polymer film-forming plugging agent LWFD and inorganic nano-plugging agent NMFD into polymer drilling fluid has comparable performance as Halliburton’s SHALEDRIL high performance drilling fluid, which can meet the requirements of on-site drilling and has application value.