다양한 파쇄 유체별 파쇄압력, 투과도 증진 및 균열전파에 관한 실험적 연구
Experimental Study on Fracture Pressure, Permeability Enhancement and Fracture Propagation using Different Fracture Fluids
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초록
치밀 저류층의 투과도 증진을 위해 개발된 수압파쇄 기술은 셰일가스와 같은 비전통자원과 심부지열 개발에 필수적인 기술 중 하나이다. 파쇄형태가 단순하고 파쇄효율이 좋지 않은 수압파쇄를 개선하기 위해 다양한 파쇄유체를 이용한 실험적 연구가 진행되었다. 물, N2, CO2 가스를 파쇄유체로 사용하여 치밀 암석에 대한 파쇄형태와 효율성을 분석하였다. 파쇄유체로 물을 일정 주입속도로 주입한 경우 순간적으로 압력이 상승하여 파쇄가 발생하였으나, 파쇄유체로 가스를 주입한 경우 서서히 압력이 증가되면서 물보다 낮은 파쇄압력을 보였다. 3D 단층촬영 기법을 이용하여 물과 가스 주입으로 생성된 균열을 관찰한 결과는 기존 공극부피 대비 파쇄 자극부피가 각각 5.71%(물), 12.72%(N2), 43.82%(CO2) 증가되었다. 또한 파쇄유체의 파쇄 효율성을 검정하기 위한 파쇄 전후 투과도 변화 실험에서는 가스 파쇄에 의해 증가되는 투과도 증가 값이 물을 이용한 파쇄보다 훨씬 높게 측정되었다. 파쇄 이후 인공균열의 생성과 주변응력에 의해 다시 균열이 닫히는 현상을 고려하여 생성된 인공균열에 구속압을 단계별로 증가시켜 투과도 변화를 측정하였다. 구속압이 2MPa에서 10MPa로 증가시켰을 경우 초기 투과도 대비 각각 89%(N2), 50%(CO2) 감소하였다. 본 연구는 가스파쇄기술이 수압파쇄보다 투과도 증진 효과가 크고 이후 주변 응력에 의한 투과도 감소가 적은 것으로 나타났다.
Abstract
The hydraulic fracturing developed to improve permeability of tight reservoir is one of key stimulation technologies for developing unconventional resources such as shale gas and deep geothermal energy. The experimental study was conducted to improve disadvantage of hydraulic fracturing which has simple fracture pattern and poor fracturing efficiency. The fracturing experiments was conducted for tight rock using various fracturing fluids, water, N2, and CO2 and the created fracture pattern and fracturing efficiency was analyzed depending on fracturing fluids. The borehole pressure increased rapidly and then made fractures for hydraulic fracturing with constant injection rate, however, gas fracturing shows slowly increased pressure and less fracture pressure. The 3D tomography technic was used to generate images of induced fracture using hydraulic and gas fracturing. The stimulated reservoir volume (SRV) was estimated increment of 5.71% (water), 12.72% (N2), and 43.82% (CO2) respectively compared to initial pore volume. In addition, permeability measurement was carried out before and after fracturing experiments and the enhanced permeability by gas fracturing showed higher than hydraulic fracturing. The fracture conductivity was measured by increasing confining stress to consider newly creating fracture and closing induced fracture right after fracturing. When the confining stress was increased from 2MPa to 10MPa, the initial permeability was decreased by 89% (N2) and 50% (CO2) respectively. This study shows that the gas fracturing makes more permeability enhancement and less reduction of induced fracture conductivity than hydraulic fracturing.
참고문헌 (31)
- Bergstrom, J. S, "Constitutive modeling ofthe large strain time-dependent behavior ofelastomers", Journal of the Mechanics and Physics of Solids, 46(5), pp.931~954 (1998)
- Blau, P, "Flushing strategies for high performance, efficient and enviromnentally friendly cutting", Procedia Cirp, 26, pp.361~366 (2015)
- Brabazon, J. W, "Rock Fracture Sorptivity as Related to Aperture Width and Surface Roughness", Vadose Zone Journal, 18(1), pp.1~10 (2019)
- Choi, J, "A study on increase the productivity optimization solution using characteristics ofgeomechanical property in Western Canada Shale Basin", Journal ofPetroleum and Sedimentary Geology, 2(1), pp.24~35 (2020)
- Coulter, G. R, "Hydraulic fracturing-new developments", Journal ofCanadian Petroleum Technology, 15, pp.04~ (1976)
- Eshkalak, M. 0, "Enhanced gas recovery by CO2 sequestration versus re-fracturing treatment in unconventional shale gas reservoirs", Abu Dhabi International Petroleum Exhibition and Conference, Society of Petroleum Engineers (2014)
- Eshkalak, M. 0, "Simulation study on the CO2-driven enhanced gas recovery with sequestration versus the re-fracturing treatment of horizontal wells in the US unconventional shale reservoirs", Journal ofNatural Gas Science and Engineering, 21, pp.1,015~1,024 (2014)
- Fallahzadeh, S. H, "Near wellbore hydraulic fracture propagation from perforations in tight rocks: the roles offracturing fluid viscosity and injection rate", Energies, 10(3), pp.359~ (2017)
- Fu, C, "Waterless fluids in hydraulic fracturing ―A review", Journal ofNatural Gas Science and Engineering, 67, pp.214~224 (2019)
- Gehne, S, "Permeability and permeability anisotropy in Crab Orchard sandstone: Experimental insights into spatio-temporal effects", Tectonophysics, 712, pp.589~599 (2017)
- Guo, F, "Interpretation of hydraulic fracturing breakdown pressure", In International Journal ofRock Mechanics and Mining Sciences & Geomechanics Abstracts, 30(6), pp.617~626
- 하성준, "액체 이산화탄소 파쇄법의 파쇄 압력, 음향 방출, 균열 형상에 관한 실험적 연구", 터널과 지하공간, 29(3), pp.157~171 (2019), 한국암반공학회[DOI]
- Ha, S. J, "Liquid CO2 fracturing: Effect of fluid permeation on the breakdown pressure and cracking behavior", Rock Mechanics and Rock Engineering, 51(11), pp.3,407~3,420 (2018)
- Hassler, G. L, "U.S. Patent No. 2,345,935", U.S. Patent and Trademark Office, ~ (1944)
- Hou, P, "Changes in breakdown pressure and fracture morphology of sandstone induced by nitrogen gas fracturing with different pore pressure distributions", International Journal of Rock Mechanics and Mining Sciences, 109, pp.84~90 (2018)
- 김재원, "현장 응력조건에 따른 암석 투과도 특성 분석", 터널과 지하공간, 27(1), pp.26~38 (2017), 한국암반공학회[DOI]
- Li, X, "Hydraulic fracturing in shale with H20, CO2 and N2", 49th US Rock Mechanics, 2015, ~
- Li, X, "Breakdown pressure and fracture surface morphology of hydraulic fracturing in shale with H20, CO2 and N2", Geomechanics and Geophysics for Geo-Energy and Geo-Resources, 2(2), pp.63~76 (2016)
- Patel, S. M, "Laboratory studies ofhydraulic fracturing by cyclic injection", International Journal ofRockMechanics andMining Sciences, 95, pp.8~15 (2017)
- Pei, P, "Shale gas reservoir trea血ent by a CO2 technology", Journal ofNatural Gas Science and Engineering,, 26, pp.1,595~1,606 (2015)
- Tanikawa, W, "Klinkenberg effect for gas permeability and its comparison to water permeability for porous sedimentary rocks" (2006)
- Veatch Jr, R. W, "An overview of recent advances in hydraulic fracturing technology", International meeting on petroleum engineering, Society of Petroleum Engineers (1986)
- Wang, J, "The influence offracturing fluids on fracturing processes: a comparison between water, oil and SC-CO2", Rock Mechanics and Rock Engineerin, 51(1), pp.299~313 (2018)
- Wang, L, "Waterless fracturing technologies for unconventional reservoirs-opportunities for liquid nitrogen", Journal of Natural Gas Science and Engineering, 35, pp.160~174 (2016)
- Wanless, H. R, "Pennsylvanian geology ofa part ofthe southern Appalachian coalfield (Vol. 13)" (1946), Geological Society of America
- Wu, Y. S, "Gas flow in porous media with Klinkenberg effects, Transport in porous Media, 32", Transport in porous Media,, 32(1), pp.117~137 (1998)
- Ju Hyeon Yu, "Hydraulic properties measurement of tight sandstone for CO2 geological storage", Geosciences Journal, 20(4), pp.551~559 (2016), 한국지질과학협의회[DOI]
- Zhang, P, "Experimental investigation on the influence ofhigh pressure and high temperature on the mechanical properties of deep reservoir rocks", Rock mechanics and rock engineering, 48(6), pp.2197~2211 (2015)
- Zhang, Z, "Advances in waterless fracturing technologies for unconventional reservoirs", Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 41(2), pp.237~251 (2019)
- Zhuang, L, "Cyclic hydraulic fracturing of pocheon granite cores and its impact on breakdown pressure, acoustic emission amplitudes and injectivity", International Journal ofRock Mechanics and Mining Sciences, 122, pp.104065~ (2019)
- Zou, C, "Tight g as sandstone reservoirs in China: characteristics and recognition criteria", Journal ofPetroleum Science and Engineering, 88, pp.82~91 (2012)