scholarly journals Carboxylated Cellulose Nanocrystals as Environmental-Friendly and Multi-Functional Additives for Bentonite Water-Based Drilling Fluids Under High-temperature Conditions

Author(s):  
Xinliang Li ◽  
Kai Wang

Abstract During the oil and gas drilling engineering, the selection of drilling fluids must take account of the technical and environmental factors. This study investigated the effectiveness of carboxylated cellulose nanocrystals (denoted as CNCs) as environmentally friendly additives in improving the rheological, filtration, and inhibitive performances of bentonite (BT) water-based drilling fluids (WBDFs). CNCs used in this study were modified by carboxylation reaction, displaying small size, negative surface charge, good colloidal stability, and prominent shear thinning behavior. The experimental results indicated that BT/CNC suspensions had superior rheological properties, low fluid loss volumes, and effective inhibition, even at 140 °C. Microstructure analysis demonstrated that CNCs could attach to the surface of BT via hydrogen bond and ionic bond. CNCs, BT, and vicinal water molecules could form a stiff gel network, which had a strong resistance to flow under shear force, leading to a significant improvement in the rheological properties. Moreover, under the differential pressure, BT/CNC suspensions formed thin and less hydrophilic filter cakes with compact layered structure, thereby efficiently decreasing the fluid loss volume. Finally, due to the gel network and filtration ability, BT/CNC suspensions performed low water activity, which was beneficial for preventing the penetration of free water into the shales and borehole well. Thus CNCs also exerted satisfactory inhibition on hydration and dispersion of BT and shales. As a result, CNCs showed great potential to be used as efficient, multi-functional, and environmentally friendly additives in WBDFs.

SPE Journal ◽  
2022 ◽  
pp. 1-17
Author(s):  
Emanuel Ricky ◽  
Musa Mpelwa ◽  
Chao Wang ◽  
Bahati Hamad ◽  
Xingguang Xu

Summary Drilling fluid rheology and fluid loss property are fundamental parameters that dictate the effectiveness and easiness of a drilling operation. Maintaining these parameters under high temperatures is technically challenging and has been an exciting research area for the drilling industry. Nonetheless, the use of drilling mud additives, particularly synthetic polymers, threaten ecological environments. Herein, modified corn starch (MCS) was synthesized, characterized, and investigated as an environmentally friendly rheology enhancer and filtration loss controlling agent for water-based mud (WBM) at high temperatures. The experimental results indicated that MCS exhibits better performance in improving rheological properties and fluid loss controlling ability for WBM than the commonly used mud additives. With the addition of an optimal concentration (0.3 wt%), MCS improved the rheology and fluid loss behavior of WBM formulation at harsh aging temperature (220°C) by practically 4 times and 1.7 times, respectively. The MCS was revealed to perform superbly over polyanionic cellulose (PAC) addition at all investigated temperatures. The better performance of the MCS was ascribed to the improved entanglements in the mud system owing to the additional hydroxyl (OH) groups. Besides, the Herschel-Bulkley model was found to be a constitutive model that described the rheological properties of the investigated muds satisfactorily. Moreover, the MCS was found to exhibit acceptable biodegradability properties.


Author(s):  
Wei-An Huang ◽  
Jing-Wen Wang ◽  
Ming Lei ◽  
Gong-Rang Li ◽  
Zhi-Feng Duan ◽  
...  

2014 ◽  
Vol 136 (3) ◽  
Author(s):  
Arild Saasen

Controlling the annular frictional pressure losses is important in order to drill safely with overpressure without fracturing the formation. To predict these pressure losses, however, is not straightforward. First of all, the pressure losses depend on the annulus eccentricity. Moving the drillstring to the wall generates a wider flow channel in part of the annulus which reduces the frictional pressure losses significantly. The drillstring motion itself also affects the pressure loss significantly. The drillstring rotation, even for fairly small rotation rates, creates unstable flow and sometimes turbulence in the annulus even without axial flow. Transversal motion of the drillstring creates vortices that destabilize the flow. Consequently, the annular frictional pressure loss is increased even though the drilling fluid becomes thinner because of added shear rate. Naturally, the rheological properties of the drilling fluid play an important role. These rheological properties include more properties than the viscosity as measured by API procedures. It is impossible to use the same frictional pressure loss model for water based and oil based drilling fluids even if their viscosity profile is equal because of the different ways these fluids build viscosity. Water based drilling fluids are normally constructed as a polymer solution while the oil based are combinations of emulsions and dispersions. Furthermore, within both water based and oil based drilling fluids there are functional differences. These differences may be sufficiently large to require different models for two water based drilling fluids built with different types of polymers. In addition to these phenomena washouts and tool joints will create localised pressure losses. These localised pressure losses will again be coupled with the rheological properties of the drilling fluids. In this paper, all the above mentioned phenomena and their consequences for annular pressure losses will be discussed in detail. North Sea field data is used as an example. It is not straightforward to build general annular pressure loss models. This argument is based on flow stability analysis and the consequences of using drilling fluids with different rheological properties. These different rheological properties include shear dependent viscosity, elongational viscosity and other viscoelastic properties.


2020 ◽  
Vol 5 (10) ◽  
pp. 1269-1273
Author(s):  
Godwin Chukwuma Jacob Nmegbu ◽  
Bright Bariakpoa Kinate ◽  
Bari-Agara Bekee

The extent of damage to formation caused by water based drilling mud containing corn cob treated with sodium hydroxide to partially replace polyanionic cellulose (PAC) as a fluid loss control additive has been studied. Core samples were obtained from a well in Niger Delta for this study with a permeameter used to force the drilling mud into core samples at high pressures. Physio-chemical properties (moisture content, cellulose and lignin) of the samples were measured and the result after treatment showed reduction. The corn cob was combined with the PAC in the ratio of 25-75%, 50-50% and 75-25% in the mud. Analyzed drilling mud rheological properties such as plastic viscosity, apparent viscosity, yield point and gel strength all decreased as percentage of corn cob increased in the combination and steadily decreased as temperature increased to 200oF. Measured fluid loss and pH of the mud showed an increase in fluid loss and pH in mud sample with 100% corn cob. The extent of formation damage was determined by the differences in the initial and final permeability of the core samples. Experimental data were used to develop analytical models that can serve as effective tool to predict fluid loss, rheological properties of the drilling mud at temperature up to 200oF and percentage formation damage at 100 psi.


Author(s):  
Bunyami Shafie ◽  
Lee Huei Hong ◽  
Phene Neoh Pei Nee ◽  
Fatin Hana Naning ◽  
Tze Jin Wong ◽  
...  

Drilling mud is a dense, viscous fluid mixture used in oil and gas drilling operations to bring rock cuttings to the earth's surface from the boreholes as well as to lubricate and cool the drill bit. Water-based mud is commonly used due to its relatively inexpensive and easy to dispose of. However, several components and additives in the muds become increasingly cautious and restricted. Starch was introduced as a safe and biodegradable additive into the water-based drilling fluid, in line with an environmental health concern. In this study, the suitability of four local rice flours and their heat moistures derivatives to be incorporated in the formulation of water-based drilling fluid was investigated. They were selected due to their natural amylose contents (waxy, low, intermediate, and high). They were also heat moisture treated to increase their amylose contents. Results showed that the addition of the rice flours into water-based mud significantly reduced the density, viscosity, and filtrate volume. However, the gel strength of the mud was increased. The rice flours, either native or heat moisture treated, could serve as additives to provide a variety of low cost and environmentally friendly drilling fluids to be incorporated and fitted into different drilling activity.


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