Prospect of shale gas recovery enhancement by oxidation-induced rock burst

You, Lijun; Kang, Yili; Chen, Qiang; Fang, Chaohe; Yang, Pengfei

doi:10.1016/j.ngib.2017.05.014

Cited by 32 publications

(31 citation statements)

References 29 publications

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“…The smaller the angle, the difference value of the in situ stress, and the hole spacing, the better the directional hydraulic fracturing effect. In addition, the directional effect of synchronous hydraulic fracturing is better than that of sequential hydraulic fracturing (5) According to the multihole linear codirectional hydraulic fracturing experiments, five typical directional hydraulic fracture propagation modes are summarized: (1) directional hydraulic fracture completely along the drilling line, (2) directional hydraulic fractures that connect boreholes but do not intersect, (3) propagation forming a ladder pattern of directional hydraulic fracture, (4) directional hydraulic fracture propagation both along the borehole line and parallel to the direction of maximum principal stress, and (5) parallel hydraulic fractures extending completely along the direction of maximum principal stress Nomenclature E c : Elastic modulus (GPa) ν:…”

Section: Discussionmentioning

confidence: 99%

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Experimental and Numerical Investigation on Basic Law of Dense Linear Multihole Directional Hydraulic Fracturing

Zhang

2021

Geofluids

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Using the dense linear multihole to control the directional hydraulic fracturing is a significant technical method to realize roof control in mining engineering. By combining the large-scale true triaxial directional hydraulic fracturing experiment with the discrete element numerical simulation experiment, the basic law of dense linear holes controlling directional hydraulic fracturing was studied. The results show the following: (1) Using the dense linear holes to control directional hydraulic fracturing can effectively form directional hydraulic fractures extending along the borehole line. (2) The hydraulic fracturing simulation program is very suitable for studying the basic law of directional hydraulic fracturing. (3) The reason why the hydraulic fracture can be controlled and oriented is that firstly, due to the mutual compression between the dense holes, the maximum effective tangential tensile stress appears on the connecting line of the drilling hole, where the hydraulic fracture is easy to be initiated. Secondly, due to the effect of pore water pressure, the disturbed stress zone appears at the tip of the hydraulic fracture, and the stress concentration zone overlaps with each other to form the stress guiding strip, which controls the propagation and formation of directional hydraulic fractures. (4) The angle between the drilling line and the direction of the maximum principal stress, the in situ stress, and the hole spacing has significant effects on the directional hydraulic fracturing effect. The smaller the angle, the difference of the in situ stress, and the hole spacing, the better the directional hydraulic fracturing effect. (5) The directional effect of synchronous hydraulic fracturing is better than that of sequential hydraulic fracturing. (6) According to the multihole linear codirectional hydraulic fracturing experiments, five typical directional hydraulic fracture propagation modes are summarized.

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Section: Discussionmentioning

confidence: 99%

“…At the same time, the hard roof above the coal seam is weakened to prevent the dynamic disaster caused by the sudden collapse of the roof. At present, this technology has been widely used in mines [1][2][3][4][5][6][7][8][9][10][11]. The geometric morphology of hydraulic fracture is the core of hydraulic fracturing construction design.…”

Section: Introductionmentioning

confidence: 99%

Experimental and Numerical Investigation on Basic Law of Dense Linear Multihole Directional Hydraulic Fracturing

Zhang

2021

Geofluids

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“…The high production is the result of increasing rig count as well as evolving technologies in drilling and completion. , However, the rapid production decline of individual wells in the first few years has required additional drilling to maintain the production level. , Previous results show that, although gas production in a shale reservoir declines rapidly, the total gas storage is far from being depleted. The low recovery rate of ∼20% − gives hope that there is still a good probability of greater gas recovery and more sustained production with new geological understanding and engineering technologies.…”

Section: Introductionmentioning

confidence: 99%

Pore Geometry Characteristics and Fluid–Rock Interaction in the Haynesville Shale, East Texas, United States

Wang

Zhou

et al. 2020

Energy Fuels

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Since 2007, the Upper Jurassic marine Haynesville Formation has become one of the leading shale gas plays and is currently the third most prolific producer in the United States. A detailed study has been performed to understand the pore geometry and fluid–rock interactions in the Haynesville organic-rich shale using 10 core samples covering a vertical profile of 123 ft in a well located in San Augustine, TX. Several complementary analyses were integrated, including well logs, petrographic microscopy, total organic carbon, X-ray diffraction, pyrolysis, mercury intrusion porosimetry (MIP), nitrogen physisorption, fluid immersion porosimetry (FIP) after vacuum saturation, contact angle measurement, and spontaneous imbibition (SI). The porosity from MIP of the marine Haynesville Shale samples ranges from 2.84 to 7.31%, greater than many other shales in North America. The shale samples analyzed here have a pore system dominated by pores with throat diameters in the 2.8–50 nm range, with associated pore volumes accounting for 69–92% of the total porosity. The results of contact angle, SI, and FIP with several fluids (aqueous and hydrocarbon) indicate that samples uptake oil preferentially. A new wettability scheme with nine categories suggests that Haynesville Shale samples vary from (i) strongly oil-wet and intermediately water-wet, (ii) intermittently mixed-wet, (iii) strongly mixed-wet, and (iv) strongly water-wet. Moreover, this integrated study of the nanoscale petrophysics provides a reasonable explanation of fracturing fluid loss and steep production decline in the Haynesville Shale.

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“…Adding oxidants as chemical additives to the fracturing fluid to improve the permeability of shale reservoirs through chemical-induced fractures has been proposed in recent years . Also, there are studies investigating shale fracturing due to shale and the oxidative fluid–H 2 O 2 interaction. − It was proved that H 2 O 2 can induce multiscale cracks, which indicate that H 2 O 2 may play a favorable role in shale matrix stimulation by oxidative dissolution.…”

Section: Introductionmentioning

confidence: 99%

Comparison of Chemical-Induced Fracturing by Na₂S₂O₈, NaClO, and H₂O₂ in Marcellus Shale

Liang

Sheng

2020

Energy Fuels

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Shale−oxidant reactions can enhance the permeability of organic-rich shale reservoirs through chemical-induced fracturing. Choosing the best oxidant for this purpose is explored in this study. To compare the effects of chemical-induced fracturing with sodium persulfate (Na 2 S 2 O 8 ), sodium hypochlorite (NaClO), and hydrogen peroxide (H 2 O 2 ) on organic-rich shale, Marcellus shale samples were used to conduct spontaneous imbibition experiments in three oxidants' aqueous solutions under no confining pressure. The mass loss of samples after oxidant imbibition, the pH change of the oxidants' aqueous solutions, the bubble density, the morphology of chemical-induced cracks, and the mineral composition alteration before and after Na 2 S 2 O 8 treatment were analyzed and discussed to evaluate the effects of three oxidants on chemical-induced cracking. Results show that the samples treated by Na 2 S 2 O 8 had the highest mass loss, while the samples treated by H 2 O 2 had the lowest mass loss. pH change results and bubble density results indicate that the rate of the chemical reactions between Marcellus shale and Na 2 S 2 O 8 or H 2 O 2 aqueous solutions during the first 24 h was the highest compared to that during the rest of the period. After 24 h, the rate of the chemical reactions decreased and then became flat until the end of the imbibition tests. Pervasive multiscale cracks formed in response to acidic and oxidative dissolutions in Na 2 S 2 O 8 imbibition tests. Although induced cracks were initiated on the surfaces of the samples treated by NaClO aqueous solutions, Fe(OH) 3 precipitates plugged the pores and prevented the cracks from developing into a favorable dimension. XRD results show that the contents of calcite, pyrite, and illite decreased after Na 2 S 2 O 8 treatment, where calcite had the largest decrease. Gypsum crystallization occurred during Na 2 S 2 O 8 imbibition. Na 2 S 2 O 8 was evaluated as the optimal oxidant among three for the initiation and propagation of chemical-induced cracks. Three concentrations (6, 12, and 15 wt %) of Na 2 S 2 O 8 solutions effectively caused chemical-induced cracks in samples, and the difference in concentrations had no significant difference in the fracturing effect. The synergy of chemical reactions between oxidant shale samples and the generated swelling stress due to crystallization contributes to crack development.

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Prospect of shale gas recovery enhancement by oxidation-induced rock burst

Cited by 32 publications

References 29 publications

Experimental and Numerical Investigation on Basic Law of Dense Linear Multihole Directional Hydraulic Fracturing

Experimental and Numerical Investigation on Basic Law of Dense Linear Multihole Directional Hydraulic Fracturing

Pore Geometry Characteristics and Fluid–Rock Interaction in the Haynesville Shale, East Texas, United States

Comparison of Chemical-Induced Fracturing by Na₂S₂O₈, NaClO, and H₂O₂ in Marcellus Shale

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Prospect of shale gas recovery enhancement by oxidation-induced rock burst

Cited by 32 publications

References 29 publications

Experimental and Numerical Investigation on Basic Law of Dense Linear Multihole Directional Hydraulic Fracturing

Experimental and Numerical Investigation on Basic Law of Dense Linear Multihole Directional Hydraulic Fracturing

Pore Geometry Characteristics and Fluid–Rock Interaction in the Haynesville Shale, East Texas, United States

Comparison of Chemical-Induced Fracturing by Na2S2O8, NaClO, and H2O2 in Marcellus Shale

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Comparison of Chemical-Induced Fracturing by Na₂S₂O₈, NaClO, and H₂O₂ in Marcellus Shale