A comparison and assessment of the modelling and simulation of the sandstone matrix acidizing process: A critical methodology study

Leong, Van Hong; Mahmud, Hisham Ben; Law, Monica; Foo, Henry Chee Yew; Tan, Inn Shi

doi:10.1016/j.jngse.2018.06.044

Cited by 19 publications

(8 citation statements)

References 12 publications

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“…As one of the most common rock types in Northern China, medium-grained sandstone has good integrity and availability; many cliff statues were cut using this type of sandstone [38,39]. However, since mediumgrained sandstone has shorter diagenesis, lower intensity, and more cements, the relics made from them deteriorate relatively faster and to a greater extent than grottoes of other lithologies (such as limestone) under the influence of natural and human factors [40,41]. After soaking in acid solution, the compression strengths of the specimens were decreased by 48-63%, suggesting that their microstructure, porosity, or mechanical characteristics might have changed [42].…”

Section: The Compression Strength Water Absorption and Effective Pormentioning

confidence: 99%

Acid solution decreases the compressional wave velocity of sandstone from the Yungang Grottoes, Datong, China

et al. 2019

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To understand the effects of an acidic environment on the internal structure of sandstone from the Yungang Grottoes, Datong, China, the physicochemical properties of fresh and weathered sandstone samples and their compressional wave (P-wave) velocities in response to different concentrations of H 2 SO 4 and HNO 3 solution were investigated. X-ray diffraction (XRD) and a scanning electron microscope equipped with energy dispersive X-ray spectrometer (SEM-EDX) were used to determine grain morphology and chemical composition. The results show that the sandstone, which mainly consists of silicon dioxide and calcium carbonate, became more complicated in composition after weathering. A nonmetallic ultrasonic detector was used to measure the P-wave velocities of sandstones in a natural state and soaked with ultrapure water and with H 2 SO 4 and HNO 3 at concentrations of 0.2 mol L −1 , 0.4 mol L −1 , and 0.8 mol L −1 , respectively. For the acid-treated groups, with increasing acidity, P-wave velocity decreased significantly, compressive strength decreased and effective porosity increased; these behaviours are different from those of the water-treat group, implying that the acid solutions damaged the microstructure of the sandstone. The results suggest that the deterioration risk of H 2 SO 4 and HNO 3 , or sulfates and nitrates converted from ambient SO 2 , NO x and PM 2.5 , on the stone relics in the Yungang Grottoes should be a cause for concern.

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Section: The Compression Strength Water Absorption and Effective Pormentioning

confidence: 99%

Acid solution decreases the compressional wave velocity of sandstone from the Yungang Grottoes, Datong, China

et al. 2019

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“…Matrix acidizing is mainly used in cases where the fracture pressure is lower than that of rock formation. 4 The acid is injected into the primary joints and surface voids, and the acid flows and dissolves through the connecting pores to effectively expand the permeable pore channels and pore space, and effectively eliminate the formation damage near the wellbore. 5,6 For sandstone reservoirs, mud acids are the most common and effective acidizing system.…”

Section: Introductionmentioning

confidence: 99%

Research on high efficiency and retarded autogenous mud acid for plugging removal in a sandstone reservoir—Example of Bai 823 well area

Li,

Yang,

et al. 2023

Energy Science & Engineering

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Acidification, as an effective measure to remove blockages and restore oil well productivity, has received widespread concern. However, conventional acid systems can only be used to unblock near‐wellbore zones and are difficult to act on far‐wellbore reservoirs. In this article, scanning electron microscope, energy‐dispersive X‐ray spectroscope, and X‐ray diffractometer were used to analyze the blockages in the Bai 823 well area, and it was determined that their main components were CaCO3 and FeCO3, which provided the basis for the construction of the unblocking formula. Then, the acid dissolution experiments on the plugging materials showed that the dissolution rate of 10% HCl can reach more than 85% for the scale sample; the acid dissolution experiments on the rock sample showed that the autogenous mud acid has better dissolution performance and better retardation performance for the rock sample, and the effective action time is longer, so it can be used for deeper unplugging of the reservoir. Finally, the process parameters such as the optimal acid concentration, acid dosage, and discharge volume were optimized by establishing the fracture‐matrix acid flow reaction model. Research results indicate that the autogenous mud acid can act on the blockage in the far‐wellbore area to improve the acidification effect.

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“…Nowadays, the academy and industry have focused on developing new technologies to improve acid stimulation in sandstone formations to mitigate the critical issues associated with the high reactivity of the acid solutions. − Most studies are focused on acid reformulation with chelating agents, solvents, and dispersants to increase the performance for fines removal . However, these new molecules increase costs, could lead to corrosion issues in the production system, and cause the formation of emulsions. − One innovative alternative is the encapsulation of acid solutions, which shows a huge potential due to the increase in the acid penetration, the control over undesirable reactions, and the reduction of the corrosion issues without lowering the acid efficiency. − …”

Section: Introductionmentioning

confidence: 99%

Development of Acid Nanocapsules with Tailored Breaking Reservoir Temperature for the Removal of Formation Damage by Fines Migration

et al. 2022

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The main objective of this study was the development of novel acid nanocapsules with tailored breaking reservoir temperatures for the controlled release of acids to dissolve fine particles. For this, thermolabile nanocapsules (NC) were synthesized using hydrofluoric acid (HF) as core and a resin/ asphaltene (R/A) mixture as the shell. For the controlled release of HF under reservoir temperature, shells with different softening points were developed through changes in the R/A ratio. The nanocapsules were characterized in terms of structure, size, and chemical using transmission electron microscopy (TEM), dynamic light scattering (DLS), and Fourier transform infrared (FTIR) spectroscopy, respectively. A nanofluid (NF) was formulated based on the dispersion of NC in the injection brine to achieve an acid concentration of 3% w•v −1 , which is a concentration commonly used for fine particles dissolution. Measurements of pH, anticorrosive power, and dissolution kinetics tests were carried out using the free and encapsulated acid at 120 °C. The characterization results verified the capsular shape, the presence of the synthesis components, the size in the nanometric regime, and the capsules' release at different temperatures. Regarding the performance tests, the nanofluid (NF) pH was 5.67, unlike the free acid, which was lower than 1. Likewise, the corrosion rate increased by 94% for free HF concerning the encapsulated acid. Dissolution kinetics were fitted to the pseudo-first-order Lagergren model with R 2 ≥ 0.90. It was observed that in the first 20 h, the dissolution rates are reduced up to 70% using encapsulated acid. Accordingly, the development of HF-based nanocapsules can increase the lifetime of the acid and reduce corrosion during the stimulation process.

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A comparison and assessment of the modelling and simulation of the sandstone matrix acidizing process: A critical methodology study

Cited by 19 publications

References 12 publications

Acid solution decreases the compressional wave velocity of sandstone from the Yungang Grottoes, Datong, China

Acid solution decreases the compressional wave velocity of sandstone from the Yungang Grottoes, Datong, China

Research on high efficiency and retarded autogenous mud acid for plugging removal in a sandstone reservoir—Example of Bai 823 well area

Development of Acid Nanocapsules with Tailored Breaking Reservoir Temperature for the Removal of Formation Damage by Fines Migration

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