Investigation on Coalbed Methane Fracturing Using Supercritical CO 2 Graphene Cement Slurry System

Dongyuan Li, Pingya Luo (), Xiaojun Peng, Tao Zou, Li Fu, Wanchun Fu and Gang Xie ()
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Dongyuan Li: State Key Laboratory of Oil & Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu 610500, China
Pingya Luo: State Key Laboratory of Oil & Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu 610500, China
Xiaojun Peng: Wuhuan Engineering Co., Ltd., Wuhan 430223, China
Tao Zou: Huabei Oilfield Company, China National Petroleum Corporation, Renqiu 062552, China
Li Fu: State Key Laboratory of Oil & Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu 610500, China
Wanchun Fu: Chengdu GSUN Energy Technology Co., Ltd., Chengdu 610219, China
Gang Xie: State Key Laboratory of Oil & Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu 610500, China

Energies, 2022, vol. 15, issue 20, 1-20

Abstract: In this study, we innovatively use sulphoaluminate cement slurry and its additives as a fracturing fluid system for supercritical CO 2 graphene-permeable cement stone (referred to hereafter as the SCGPCS) fracturing without sand. Utilizing small fluid volumes, small displacement and small pump pressure, we obtain the success of the first field test in an extra-low desorption pressure coal seam. Laboratory experiments have proven that sulphoaluminate cement is suitable as base cements for the SCGPCS system due to their rapid setting and fast hardening characteristics. The reaction of sodium carbonate + aluminum sulfate system and sodium bicarbonate + aluminum sulfate system will generate precipitation to block the internal pore structure of cement stone, leading to a decrease in permeability. Calcium hypochlorite (1.5 wt.%) + urea (0.6 wt.%) system is preferred as a gas-generating agent system for SCGPCS. Sand (30 wt.%) with 300–425 μm particle size is preferred as a structural strength substance for SCGPCS. Graphene poly-gel (referred to hereafter as the GPG) has a high FCI and good CO 2 foam stability. GPG (6.0 wt.%) is preferred as a foam stabilizer for SCGPCS. The thickening time of graphene–foam–cement slurry is 138 min at 50 °C, with long pumping time, normal thickening curve and excellent performance. The SCGPCS has a corrosion rate of 11.25 mpy in the formation water and can be stable in the formation. Acid is more corrosive to SCGPCS, and it can be used to improve the permeability of SCGPCS. Field tests have proven that SCGPCS fracturing injected 33 m 3 of fluid, of which 27 m 3 entered the formation. Graphene–foam–cement slurry was injected into the formation through the casing for 13 m 3 , with a displacement of 0.4–0.6 m 3 /min and tubing pressure 8–13 MPa. The formation was fractured with a fracturing crack half-length of 71.58 m, a supported fracturing crack half-length of 56.95 m, and a supported fracturing crack permeability of 56.265 mD.

Keywords: supercritical CO 2; permeable cement stone; sulphoaluminate cement; graphene poly-gel; permeability; compressive strength; coalbed methane fracturing (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2022
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