Acid-etched fracture length and conductivity experiments with relayed large-scale rock plates

Liu, Fei; Ma, Hui; Li, Li; Zhou, Changlin; Luo, Zhifeng; Gao, Xinping; Wu, Yong

doi:10.1016/j.petrol.2020.107978

Cited by 15 publications

(4 citation statements)

References 8 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The conductivity test of the acid etched fracture is one of the important indexes for calculating the effective action distance of acid and evaluating the effect of acid compression. 26 Through this test, we can understand the fracture conductivity morphology of artificial fractures and natural fractures after acid–rock reaction under high temperature and pressure. According to the diversion experiment scheme, the rock slab was etched with H at 160 °C and C at 180 °C to establish an artificial fracture channel.…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Self-Generated Organic Acid System for Acid Fracturing in an Ultrahigh-Temperature Carbonate Reservoir

Zhang¹,

Liu

Xiong³

et al. 2023

ACS Omega

View full text Add to dashboard Cite

As an important part of acid fracturing technology for the carbonate reservoir, the performance of the acid system directly affects the stimulation effect. In view of the current problems of an acid fluid system in an ultrahigh-temperature carbonate reservoir, such as fast acid–rock reaction, short effective action distance, and difficulty maintaining the conductivity of acid etching fractures, an experimental study on the self-generated organic acid system was carried out. The results showed that acetic anhydride and ethyl acetate, which had a strong acid generating ability, were suitable for the parent acid types of self-generated organic acids. Preferably, the peak temperature of 25% acetic anhydride is 160 °C, while the peak temperature of 30% ethyl acetate is 180 °C. The acid–rock reaction kinetics experiment shows that the order of activation energy is ethyl acetate > acetic anhydride > cross-linked acid. The reaction rate is arranged as follows: ethyl acetate < acetic anhydride ≪ cross-linked acid. The self-generated organic acid of ethyl acetate has the largest activation energy, the smallest reaction rate, and the best retarding effect. Acetic anhydride forms a strong nonuniform pitting morphology on the surface of the rock plate, with an initial conductivity of 225.4 μm2·cm. Ethyl acetate forms an uneven pitting morphology, and the initial conductivity is 53.1 μm2·cm. However, the ability of acid etching fracture formed by ethyl acetate to maintain fracture conductivity is stronger than that of acetic anhydride. Ethyl acetate is more suitable for a deep ultrahigh-temperature carbonate reservoir.

show abstract

Section: Resultsmentioning

confidence: 99%

“…To evaluation the conductivity, we tested the permeability and conductivity of the etched plates in water. , The etched plates are loaded into the gripper and sealed. After adding a certain confining pressure, we opened the advection pump and emptied the gas in the pipeline at a flow rate of 3 mL/min.…”

Section: Experimental Methodsmentioning

confidence: 99%

Self-Generated Organic Acid System for Acid Fracturing in an Ultrahigh-Temperature Carbonate Reservoir

Zhang¹,

Liu

Xiong³

et al. 2023

ACS Omega

View full text Add to dashboard Cite

show abstract

“…The etched surface morphology is one of the significant factors to influence the carbonate acid fracturing treatment. If the etching pattern is complicated, it is favorable for oil and gas flows. , To further explore the effect of surfactant adsorption on the surface after etching, the rock surface is digitally characterized after the reaction using laser scanning and three parameters ( h s , , and S). Figure shows the etched surface morphology and height difference frequency distribution.…”

Section: Resultsmentioning

confidence: 99%

Ability to Inhibit H⁺ Transmission of Gemini Surfactants with Different Chain Lengths under Different Ca²⁺ Circumstances

et al. 2022

View full text Add to dashboard Cite

To study the ability to inhibit ion transmission of the Gemini surfactant under different Ca 2+ circumstances, three kinds of Gemini surfactants with different alkyl chain lengths are synthesized (C n -4-C n , n = 12, 14, and 16), which are characterized using 1 H NMR, 13 C NMR, and Fourier transform infrared spectroscopy. To analyze the property of inhibition of the acid–rock reaction rate, surface tension and contact angle measurements and atomic force microscopy (AFM) results are obtained with different surfactants and under different Ca 2+ concentrations. Inhibition rates with different alkyl chain lengths and an acid-etched surface morphology are also studied carefully. The result shows that all cationic Gemini surfactants significantly impact the control of the reaction rate, and the reaction rate decreased remarkably by 44.4% after adding 12-4-12. The Δ G and W A indicate that 12-4-12 has the best adsorption ability on the rock with added Ca 2+ compared with the other two Gemini surfactants. It is revealed through the AFM that Ca 2+ can significantly change the adsorption morphology of the surfactant. The surfactant adsorption area decreased when Ca 2+ is dispersed in the solution as well. These two phenomena can lead to the reduced ability to block H + of 14-4-14 and 16-4-16. However, the presence of Ca 2+ affects the adsorption area of 12-4-12 slightly. Thus, the reaction rate, including that of 12-4-12, is almost unchanged. Because 12-4-12 is adsorbed tightly on the rock surface, H + can only react with the rock on the unabsorbed dot, resulting in rock surface nonuniformity after being etched, which is beneficial for maintaining the conductivity of the crack.

show abstract

“…Evaluation of conductivity is to test the permeability and conductivity of etched plates of water. , The etched plates are loaded into the gripper and sealed. After adding a certain confining pressure, we need to open the advection pump and empty the gas in the pipeline at a flow rate of 0.61 in.…”

Section: Experimental Sectionmentioning

confidence: 99%

Experimental Study on the Autogenic Acid Fluid System of a High-Temperature Carbonate Reservoir by Acid Fracturing

Guo

Liu

et al. 2022

ACS Omega

View full text Add to dashboard Cite

As an important part of the acid fracturing process of carbonate reservoir, the performance of acid fracturing working fluid directly affects the stimulation effect of oil wells. In this paper, formaldehyde (agent A) and ammonium chloride (agent B) were used as the matrix. Several aldehydes with different volume ratios were prepared. The acid ratio with the highest acid yield was selected by the sodium hydroxide titration experiment. The results show that when the volume ratio of agent A to agent B is 1:1.3, the acid production capacity is the strongest. The pH values at several time points in the process of acid reaction were measured by a pen pH meter. The relationship curve between acid production capacity and time was obtained. The acid production capacity increased with time. It tends to be stable after a certain time. The experiment of acid rock reaction kinetics shows that the reaction rate between acid and rock decreases with the extension of time. The reaction time can reach 6 h. The reaction rate of autogenic acid under different temperatures and concentrations ranges from 6.61 × 10 –7 to 9.49 × 10 –7 mol/(s·cm 2 ) within 6 h. Therefore, it indicates that the reaction time between autogenic acid and carbonate rock is long and the reaction rate is low. It is beneficial to improve the acid treatment effect of the carbonate reservoir. The conductivity experiments show that at different temperatures, with the increase of sealing pressure, the etching ability of autogenic acid decreases. The etching effect is better at 338 K. After etching, the permeability and conductivity of the rock slab of 5 MPa closure pressure are 227 D and 72.62 D·cm, respectively. To sum up, this autogenic acid is an effective working fluid in the acid fracturing process of the carbonate reservoir. It can obviously reduce the reaction rate of acid rock and has certain conductivity.

show abstract

Acid-etched fracture length and conductivity experiments with relayed large-scale rock plates

Cited by 15 publications

References 8 publications

Self-Generated Organic Acid System for Acid Fracturing in an Ultrahigh-Temperature Carbonate Reservoir

Self-Generated Organic Acid System for Acid Fracturing in an Ultrahigh-Temperature Carbonate Reservoir

Ability to Inhibit H⁺ Transmission of Gemini Surfactants with Different Chain Lengths under Different Ca²⁺ Circumstances

Experimental Study on the Autogenic Acid Fluid System of a High-Temperature Carbonate Reservoir by Acid Fracturing

Contact Info

Product

Resources

About

Acid-etched fracture length and conductivity experiments with relayed large-scale rock plates

Cited by 15 publications

References 8 publications

Self-Generated Organic Acid System for Acid Fracturing in an Ultrahigh-Temperature Carbonate Reservoir

Self-Generated Organic Acid System for Acid Fracturing in an Ultrahigh-Temperature Carbonate Reservoir

Ability to Inhibit H+ Transmission of Gemini Surfactants with Different Chain Lengths under Different Ca2+ Circumstances

Experimental Study on the Autogenic Acid Fluid System of a High-Temperature Carbonate Reservoir by Acid Fracturing

Contact Info

Product

Resources

About

Ability to Inhibit H⁺ Transmission of Gemini Surfactants with Different Chain Lengths under Different Ca²⁺ Circumstances