Experimental study on alleviating water-blocking effect and promoting coal gas desorption by gas wettability alteration

Wang, Liang; Wang, Bo; Zhu, Jintuo; Liao, Xiaoxue; Ni, Sijia; Shen, Shuyi

doi:10.1016/j.jngse.2022.104805

Cited by 16 publications

(6 citation statements)

References 36 publications

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“…Especially in sandstone reservoirs, which suffer from water blockage due to the hydrophilic nature of the rock. 53 Figure 13 shows the results of the turbidity test. The turbidity of the solutions shows a significant increase after effective mixing with salinities higher than 80,000 ppm.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

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Modifying the Wettability of Carbonate Gas Condensate Reservoirs Rocks toward Gasophilic for Condensate Blockage Removal and Enhanced Hydrocarbon Recovery Using a Synthesized Anionic Fluorinated Surfactant

2023

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Chemical treatment is used to remove gas condensate blockage near the wellbore of reservoirs. In this regard, a fluorinated surfactant (F-surfactant) with anionic charge was prepared, characterized, and tested as a wettability-modifying agent for the treatment of carbonate rock in laboratory quantities. To measure this application, related tests including surface tension, contact angle, imbibition, adsorption, and salt resistance were performed. In addition to the successful synthesis, the results show that the temperature degradation of the F-surfactant does not happen easily, and it maintains its structure at the reservoir temperature. The concentration of 525 ppm was determined as the critical micelle concentration (CMC). The F-surfactant effectively reduced the surface tension of the condensate/hydrocarbon gas system. Thus, the surface tension values in concentrations of 125, 225, 325, 425, 525, 625, and 725 ppm were 21.36, 15.843, 10.89, 4.47, 2.936, 2.617, and 2.382 mN/m, respectively. Reducing the surface tension in the condensate/hydrocarbon gas system strengthens an effective mechanism for the production of condensate from the area around the well called the “positive coupling effect”. The wettability of carbonate rock altered to gasophilicity at low concentrations and the average contact angle at concentrations of 425, 525, and 625 ppm increased to 117.10, 121.11, and 127.32°, respectively, after the completion of the aging time. The synthesized F-surfactant has significant adsorption based on the decrease in concentration per injected pore volume (PV) in the carbonate plug. In this way, the adsorption percentage per 2 PV was equal to 12.28%. Mediators and adsorption mechanisms in this case are related to rock and F-surfactant molecules interactions. Based on turbidity measurement, the F-surfactant solutions are compatible with up to 80,000 ppm salinity.

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Section: ■ Results and Discussionmentioning

confidence: 99%

“…In this case, the chemical solution can come into contact with salt water in areas subject to saltwater inundation. Especially in sandstone reservoirs, which suffer from water blockage due to the hydrophilic nature of the rock Figure shows the results of the turbidity test.…”

Section: Resultsmentioning

confidence: 99%

Modifying the Wettability of Carbonate Gas Condensate Reservoirs Rocks toward Gasophilic for Condensate Blockage Removal and Enhanced Hydrocarbon Recovery Using a Synthesized Anionic Fluorinated Surfactant

2023

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“…The greater the capillary pressure, the greater the resistance, and the more difficult is the gas migration. When the capillary pressure is reversed to negative, it transforms into the driving force and promotes the migration of CBM [46,47]. The smaller the capillary pressure is, the greater the driving force.…”

Section: Capillary Pressure Changes Induced By Contact Angle and N 2 ...mentioning

confidence: 99%

The Wetting Characteristics and Microscopic Wetting Mechanism of Coal under High-Pressure Nitrogen Environment

Long,

Shi,

Cao

et al. 2024

Processes

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The wettability of coal is an important factor influencing hydraulic stimulation. Field-trial data has proven that high-pressure N2 injection plays a positive role in increasing the coalbed methane (CBM) production rate. For the purpose of investigating the mechanism by which N2 promotes the gas rate, multiple experiments were conducted sequentially on the wettability of anthracite under different N2 pressures. Testing of the coal surface contact angle was conducted under 0.1–8 MPa nitrogen pressure using a newly built contact angle measuring device. The coal samples were collected from the Xinjing Coal Mine in the Qinshui Basin, China. The test results revealed that the contact angle increased with increasing N2 pressure. That is, the contact angle was 77.9° at an N2 pressure of 0.1 MPa and gradually increased to 101.4° at an infinite N2 pressure. In contrast, the capillary pressure decreased with an increasing N2 pressure, from 0.298 MPa to −0.281 MPa. The relationship between the contact angle and N2 pressure indicates a reversal of the wettability, at 5.26 MPa, with a contact angle of 90° and a capillary pressure of 0 MPa. The capillary pressure reversed to a negative value as the N2 pressure increased. At the microlevel, a high N2 pressure increases the surface roughness of coal, which improves the ability of the coal matrix to adsorb N2, forming the gas wall that hinders the intrusion of water into the pores of the coal matrix. The results of this study provide laboratory evidence that high-pressure N2 injection can prevent water contamination and reduce the capillary pressure, thus benefiting coalbed methane production.

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“…A significant outburst of coal and gas accidents will be accompanied by energy release, which produces strong power in the period of underground mining. − Gas outburst produces a large amount of pulverized coal, and the desorption gas of pulverized coal will further facilitate the outburst. − Therefore, gas significantly influences the gestation and occurrence of gas outbursts. − As coal mining depths increase, the amount and intensity of gas emissions also increase, which will induce more gas calamities. − In addition to the high-intensity mining stage of deep coal seams, the coal has been strongly damaged many times during the coal-forming process, leading to the gas migration in the coal body and the circumstance of gas desorption–pulverization–desorption. , Consequently, studying the law of gas desorption in coal under damage conditions is crucial for understanding gas emission laws and gas flow mechanisms and predicting coal and gas outbursts. − …”

Section: Introductionmentioning

confidence: 99%

Characterization of Coal Particle Methane Desorption and Optimization of Desorption Model Based on Desorption Damage

Fu,

Liu,

et al. 2024

ACS Omega

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In view of the current situation where most studies on gas desorption characteristics are limited to the atmospheric pressure desorption environment, we have independently developed a coal methane desorption instrument to test the nonatmospheric pressure desorption characteristics for coal particle gas beneath the condition of desorption damage. The instrument can arbitrarily adjust the gas pressure in the range of measurement while controlling the instantaneous release of excess gas to keep the desorption environment pressure constant. We measured the methane desorption amount of coal samples with different desorption times within 3 h and calculated the desorption velocity. The results show that the final desorption amount and desorption velocity of gas scale up with the increase of times, and the final desorption amount of coal sample W-01 increases the most, which is 18.5%. With the passage of time, the diffusion coefficient decreases gradually, and the number of desorption times is directly proportional to the diffusion coefficient. Its relative deviation of diffusion coefficient between different desorption times of the same coal sample can reach up to 40%, and the desorption time in the range of 5 to 30 min is the area with high relative deviation. A quantitative index K i of a double-parameter damage model based on desorption conditions and adsorption pressure is proposed, and the damage extent of each sample is evaluated. The damage quantitative index of coal sample W-01 is the highest, which is 0.87. The methane desorption model of coal under the condition of desorption damage is constructed, and more than 30 groups of experiments are verified.

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Experimental study on alleviating water-blocking effect and promoting coal gas desorption by gas wettability alteration

Cited by 16 publications

References 36 publications

Modifying the Wettability of Carbonate Gas Condensate Reservoirs Rocks toward Gasophilic for Condensate Blockage Removal and Enhanced Hydrocarbon Recovery Using a Synthesized Anionic Fluorinated Surfactant

Modifying the Wettability of Carbonate Gas Condensate Reservoirs Rocks toward Gasophilic for Condensate Blockage Removal and Enhanced Hydrocarbon Recovery Using a Synthesized Anionic Fluorinated Surfactant

The Wetting Characteristics and Microscopic Wetting Mechanism of Coal under High-Pressure Nitrogen Environment

Characterization of Coal Particle Methane Desorption and Optimization of Desorption Model Based on Desorption Damage

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