Productivity enhancement by stimulation of natural fractures around a hydraulic fracture using micro-sized proppant placement

Keshavarz, Alireza; Badalyan, Alexander; Johnson, Raymond L.; Bedrikovetsky, Pavel

doi:10.1016/j.jngse.2016.03.065

Cited by 74 publications

(19 citation statements)

References 19 publications

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“…In order to remove the plugging, various technologies (Palmer et al, 1993;Ni et al, 2012;Keshavarz et al, 2016;Teng et al, 2016;Xu et al, 2017) such as acidizing, repeated fracturing, cavity completion, high energy gas injection, and electric pulse have been explored and tested in the field. The effect of these technologies has been partly good and partly poor, and it has changed with the area.…”

Section: List Of Figuresmentioning

confidence: 99%

Feasibility Analysis and Optimal Design of Acidizing of Coalbed Methane Wells

Guo

Chen²,

Yao

et al. 2019

Journal of Energy Resources Technology

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Plugging is a prominent reason for production reduction in coalbed methane (CBM) wells. In order to solve this problem, authors conducted the feasibility analysis and optimal design of acidizing of CBM wells to remove the plugging in Hancheng block (H block) China. First, X-ray diffraction analysis shows that the plugging contains acid-soluble minerals and the field case indicates that acidizing effect is positively correlated with the content of acid-soluble minerals. Inspired by this, authors analyze determining factors of the content of acid-soluble minerals. Well logging parameters (DEN, AC, GR) are selected to establish a neural network model to predict the content of acid-soluble minerals. Furthermore, a feasibility criterion of acidizing of CBM wells is proposed. Then, a forward model and an inversion algorithm are proposed to diagnose the plugging. The multisolution problem of parameters inversion is solved by the Gauss–Marquardt (G-M) algorithm based on the stochastic initial value and maximum probability. Combining this method with the current numerical model of acidizing, authors present an optimal design in order to optimize the volume and injection rate of the acid. Meanwhile, by experimental study, authors propose a new acid formulation. Finally, results have been applied in the field to confirm the feasibility of the acidizing. It turns out that acidizing is an effective stimulation technology for some specific CBM wells, and the feasibility analysis and the optimal design can improve the effect of acidizing of CBM wells.

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Section: List Of Figuresmentioning

confidence: 99%

Feasibility Analysis and Optimal Design of Acidizing of Coalbed Methane Wells

Guo

Chen²,

Yao

et al. 2019

Journal of Energy Resources Technology

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“…Once CO2 in injected, it reacted to form carbonic acid. But carbonic acid (H2CO3) is unstable in water solution, and decomposes to form H + and HCO3 − (Equations (4) and (5). Meanwhile HCO3 − decomposed into H + and CO3 2− (Equation (6)).…”

Section: Variation Of Ion Contentmentioning

confidence: 99%

“…However, low permeability of coal bed reservoirs in China is a major challenge faced by the CBM industry, leading to a low yield of the existing CBM wells [2][3][4]. Various permeability enhancement techniques such as hydraulic fracturing, nitrogen foam fracturing, and methane displacement by CO 2 have been employed to promote transport of CBM and increase its recovery rate [5][6][7]. Among these methods, the CO 2 -enhanced CBM recovery (CO 2 -ECBM) technique not only enables the geological storage of CO 2 gas (which can reduce greenhouse gas emissions), but also optimizes the CBM recovery process, leading to significant economic and environmental benefits.…”

Section: Introductionmentioning

confidence: 99%

Experimental Study of CO2-Water-Mineral Interactions and Their Influence on the Permeability of Coking Coal and Implications for CO2-ECBM

Guo

Wang

et al. 2018

Minerals

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Abstract:Coal permeability is one of the most critical parameters affecting gas flow behavior during coalbed methane (CBM) production. However, little research has been conducted on how permeability evolves after CO 2 injection in coking coal. Hence, examining possible chemical interactions between coal minerals, water, and injected CO 2 can be very helpful to better characterize coking coal. In this study, coking coal specimens obtained from the Malan and Tunlan mines located in the Gujiao block of the Qinshui basin were treated with water and CO 2 to achieve a better understanding of their dissolution kinetics, pore structure, and permeability. It was found that the relative carbonate mineral content decreases with time, while the relative clay mineral content increases after the reaction with CO 2 and water. Scanning electron microscopy (SEM) confirmed these mineral alteration phenomena. Carbonate minerals (calcite, dolomite) dissolve faster than clay minerals (montmorillonite, illite and kaolinite). In particular, the dissolution rates of Ca 2+ in carbonate minerals increases with decreasing temperature (25-45 • C) and pH (4.3-6.3), and the dissolution rate of Ca 2+ ions in the calcite reaction solution is higher than that in the dolomite solution. In addition, the results of low-pressure nitrogen adsorption analysis showed that CO 2 injection can enlarge smaller size pores into larger size pores and change the overall pore size distribution. Therefore, CO 2 injection can increase the porosity of coal beds and ultimately their permeability, which in turn facilitates CBM production.

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“…Through the fracturing of XJ-1 well, the state of stress concentration in the area will be changed, achieving the purpose of eliminating outburst. This significantly improves the diversion of the coal seam gas flow to improve the seepage flow characteristics of the target coal seam near the well, thus improving the output of the well (Keshavarz et al, 2016). There are significant differences between the reservoir characteristics of the coal seam and the ordinary oil and gas reservoirs.…”

Section: The Hydraulic Fracturing Effectmentioning

confidence: 99%

The case for enhanced coalbed methane using hydraulic fracturing in the geostructural belt

Sun

et al. 2018

Energy Exploration & Exploitation

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Coal and gas outbursts mostly occur during mining at geostructural belts. Pre-drainage coalbed methane using hydraulic fracturing is one of the methods to prevent outbursts. However, the coal in geostructural belts is to be soft and crushed with special mechanical properties and pore structure. To explore the feasibility of hydraulic fracturing in geostructural belts, a field investigation on enhanced coalbed methane using hydraulic fracturing with vertical well was conducted at the Yangquan Coalfield, China. This case puts forward a method for the location selection of vertical well in geostructural belts. In addition, a triple-control technology for hydraulic fracturing, which is characterized by pressure control, flow control and sand ratio control of fracturing fluid, is presented. The results show that the average gas production and maximum gas drainage capacity of the test well were 5.67 and 12.88 times than those of the regular well, respectively, achieving good drainage effects.

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Productivity enhancement by stimulation of natural fractures around a hydraulic fracture using micro-sized proppant placement

Cited by 74 publications

References 19 publications

Feasibility Analysis and Optimal Design of Acidizing of Coalbed Methane Wells

Feasibility Analysis and Optimal Design of Acidizing of Coalbed Methane Wells

Experimental Study of CO2-Water-Mineral Interactions and Their Influence on the Permeability of Coking Coal and Implications for CO2-ECBM

The case for enhanced coalbed methane using hydraulic fracturing in the geostructural belt

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