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Abstract Wellbore stability and formation damage are of great interest and significance in drilling industry. It is estimated, each year, millions of dollars are lost due to wellbore instability problems which are resulting from exposure of shale to drilling muds. The main objective of this research activity is to improve shale inhibition and wellbore stability by using Silica nanoparticles in mud formulation. Furthermore, it is also intended to use this nanoadditive as a multifunctional mud additive to decrease fluid loss, improve lubricity, avoid shale swelling and modify rheological properties. In order to achieve these objectives, experimental procedures have been planned in the following sequences; A) Different concentrations of Silica nanoparticles are used in conducting experiments in order to determine the nanoparticles concentration range that yields the optimum shale inhibition. B) Further experiments are conducted on the evaluation of rheological properties and fluid loss via API standard methods. C) Lubricity and shale swelling tests are performed via relevant standards. D) Overall evaluation of laboratory-prepared water based drilling fluid is performed and the results are presented and compared with the blank samples. In conclusion, according to the acquired results including nanoadditives in drilling fluid and comparing them with blank samples, it was found that the most economical and effective concentration of nanoparticles is below 1% w/v, which lead to an acceptable shale inhibition effects by plugging the nanosized pores. These effects are analyzed and reported graphically. Various charts and figures show the enhancement in rheological properties such as yield point by adding small amount of nanoadditive in comparison with ordinary vicosifiers in drilling fluids. The most significant achievement in this research is the cost effectiveness of the nanoadditive. Not only can we improve mud performance with a lower cost in comparison with previously used drilling additives, but also by further modifications, these additives can replace the ordinary drilling additives. Needless to say that such change has a considerable reduction in drilling fluids costs. Several works have accomplished in relation with applying Silica nanoparticles in drilling fluid formulation and approximately in all of these works, only higher concentrations of nanoparticles (more than 10%wt) can be applicable in the shadow of surfactants and ultrasonication methods for sufficient dispersion. The striking feature of this research is the consuming of nanoparticles in lower concentrations (maximum 1% w/v) and without the assistance of surfactants.
Abstract Wellbore stability in high reactive shales is one of the operator challenges leading them to use OBM and WBM with different inhibitors such as KCL, glycols, amines ant etc. Environmental concerns restrict the OBM and Amines usages, but knowledge shortage in relation with inhibition mechanisms, still preserve KCL\polymer mud as an efficient solution even in sensitive areas. Cost effective silica-alumina nano drilling fluids as KCL substitution, provides inhibition both mechanically and chemically which is not achievable by other inhibitors. The silica-alumina nano-drilling fluid system is designed in different mud weights without consuming KCL. This fluid system is subjected to hot rolling for 4, 8 and 16 hrs at 250 and 300 °F in the presence of highly reactive montmorillonite shale. All mud properties including shale recovery, rheological properties, fluid loss, foaming, lubricity and mud cake quality were evaluated before and after hot rolling. Also the stability of the nano based drilling fluid system in different salinities and probable contaminations were examined and finally all the results and cost evaluation were compared with ordinary high performance drilling fluid systems such as KCL\polymer, KCL\PHPA\Glycol. The collected data from experimental results are compared to high performance water based drilling fluids such as KCL\polymer or KCL\PHPA\Glycol drilling fluid systems, somewhat cationic polymers or amine chemistry. This nano-drilling fluid possesses the most shale inhibition characteristic between 90-99% which is higher than the other aforementioned systems. (This value is really comparable with OBM having the highest shale inhibition among the others). Rheological properties like PV (plastic viscosity) and YP (Yield Point) remain relatively constant in an acceptable level; in that PV and YP decrease level is lower than 20% which is the half of the efficient KCL containing muds. The fluid loss is sufficiently controlled, less than 5 cc even at high temperatures, and lubricity effect provides us with a really acceptable Kf (friction of coefficient factor), under 0.2, which enables applying the system in high deviated zone or directional drilling. Stability tests show that this system has no incompatibility with high salinities and is adequately resistant in presence of contaminations. Also this system is applicable in the presence of weighting agents. Finally cost comparisons and environmental evaluations introduce this system as a cost benefit and environmental friendly system. The most striking feature of this research is to apply cost effective silica-alumina nano drilling fluid to replace the conventional inhibitors which are not economical and environmentally friendly such as KCL. Significantly by introducing this system, we can diminish the high costs of synthesizing cationic polymers or amine compounds for shale drilling in sensitive areas and highly reactive shale.
Abstract Drilling fluid design for shale plays aims to prevent wellbore instability problems associated with fluid invasion, shale swelling, and cuttings dispersion. Although oil-based mud (OBM) can be used to achieve these goals, environmental and economic concerns limit its application. This research evaluates the potential of using silica nanoparticles (SiO2-NPs) and graphene nanoplatelets (GNPs) as drilling fluid additives in a single formulation to improve shale inhibition and long-term stability of water-based mud (WBM) against temperature effects. The design of the nanoparticle water-based mud (NP-WBM) followed a customized approach that selects the additives according to the characteristics of the reservoir. Characterization of Woodford shale was completed with X-ray diffraction (XRD), cation exchange capacity (CEC), and scanning electron microscopy (SEM). The aqueous stability test and zeta-potential measurements were used to assess the stability of the NPs. NP-WBM characterization included the analysis of the rheological properties measured with a rotational viscometer and the evaluation of the filtration trends at low-temperature/low-pressure (LTLP) and high-temperature/high-pressure (HTHP) conditions. Additionally, dynamic aging was performed at temperatures up to 250°F for thermal stability evaluation. Finally, chemical-interaction tests such as cutting dispersion and bulk swelling helped to analyze the effect of introducing NPs on the inhibition capabilities of the WBM. Conventional KCl/PHPA fluid was used for comparison purposes. The results of this investigation revealed that SiO2-NPs and GNPs acted synergistically with other additives to improve the filtration characteristics of the WBM with only minor effects on the rheological properties. NPs exhibited a high colloidal stability with ζ-potential values below-30 mV, which warrants their dispersion within the WBM at an optimal concentration of 0.75 wt.%. The high thermal conductivity of NPs played a key role in promoting an almost flat trend in the cumulative filtrate for the NP-WBM at aged conditions, whereas KCl/PHPA suffered a drastic increase. Also, NP-WBM preserved 43.97% of its initial cutting carrying capacity, while KCl/PHPA experienced a severe reduction of 95.24% at extreme conditions (250°F). Despite the high illite content of the Woodford shale, the NP-WBM exhibited superior inhibition properties that reduced cutting erosion and swelling effect by 24.48% and 35.24%, respectively, compared to the KCl/PHPA fluid. Overall, this investigation supports the potential use of nanomaterials to enhance the inhibition capabilities and the long-term stability of WBM for unconventional shales, presenting an eco-friendly alternative for harsher environments.
Abstract Water-based drilling fluids are the most commonly used of the mud systems. High Temperature and Foam Free Water Based Drilling Fluids has been designed for controlling the rheological and filtration and foam properties of water based drilling mud under down-hole conditions. This unique drilling fluids system has been developed to improve water based drilling operation's speed and save the drilling cost while reducing their environmental impact for rheology and filtration control at high temperatures. Specially-formulated fluid has good lubricity and low toxicity, and at the same time do not create significant foam and corrosion in during drilling operation. This drilling fluids system's unique chemical structure enables this system to provide multifunctional properties such as surface tension reduction, foam control, and viscosity stabilization, HPHT fluid loss controller. This new drilling fluids system is formulated by using special HPHT synthetic polymers and specialty additives to reduce HPHT fluid loss of the system and provide maximum shale inhibition in HPHT wells, limitation of foam, and increasing ROP. This system significantly reduced the degradation of polymers and fluid loss additives in WBMs up to 375 °F and increase the rheological and filtration stability to improve the thermal stability in higher temperature environments. Experimental results from the performance of this product have been acceptable in down-hole conditions. This also reduces cost and logistics issue especially in offshore and extend the thermal temperature limitations of standard system components, premium starch derivatives and XC polymers. In present work, laboratory evaluation of specially-formulated fluids to enhance the properties of the HPHT water based drilling mud was investigated. We put and maintain specialty chemicals in from the beginning operation and we did not experience foaming, ever!
Abstract The knowledge about rheological models is critical for a drilling fluid study. Typical drilling fluids have lower rheological properties in higher temperature or increase in gel properties which is the main reason for frictional losses when circulating. Keeping the rheological properties with constant value is one of the challenges to manage ECD and its effects. Our main goal is to introduce a flat rheology water based mud in order to improve fluid stability and prevent loss circulations and robustness while drilling operation. The newly developed flat rheology water based drilling fluid system is formulated in different mud weights 1.12 S. G – 2.15 S. G to keep the shale inhibition, temperature stability and rheological properties in the highest possible performance. This fluid system was subjected to hot rolling for 8 hours at 250 °F and 300 °F. Rheological properties were measured before and after hot rolling in several temperatures in order to confirm the flat and stable rheology. As well, other properties like shale recovery, fluid loss and lubricity were measured. After hot rolling (250 °F and 300 °F) rheology measurements were performed with Fann Viscometer for each mud in different temperature and pressures (60 °F to 180 °F) and the results were collected to be compared with before hot rolling data in the same conditions. All rheological data (PV, YP, Gels and etc.) remained the same comparing the properties before hot rolling. This water based mud possesses the highest shale inhibition (shale recovery ranges from 95-100%). The API-fluid loss and HPHT-Fluid Loss were sufficiently controlled. Lubricity effect provided us with a really acceptable Kf (coefficient friction factor), under 0.2, which enables applying the system in high deviated zones or directional drilling. Stability tests show that this system has no incompatibility with high salinities and is adequately resistant in presence of contaminations. Also this system is applicable in the presence of weighting agents. Finally cost comparisons and environmental evaluations introduce this system as a cost benefit and environmental friendly system. The most striking feature of this research is to design and introduce a flat rheology water based drilling fluid replacing conventional drilling fluid systems with temperature and pressure independent rheology along with other qualified characteristics. Significantly, this system is sufficiently environmental friendly and cost effective.