Geological problems in the effective development of deep shale gas: a case study of Upper Ordovician Wufeng-Lower Silurian Longmaxi formations in Sichuan Basin and its periphery
He Zhiliang1,2,3, Nie Haikuan1,2,4, Hu Dongfeng5, Jiang Tingxue1,6, Wang Ruyue1,2,4, Zhang Yuying7, Zhang Guangrong8, Lu Zhiyuan8
1. State Key Laboratory of Shale Oil and Gas Enrichment Mechanisms and Effective Development, Beijing 100083, China;
2. Sinopec Key Laboratory of Shale Oil/Gas Exploration & Production, Beijing 100083, China;
3. Department of Science and Technology, China Petroleum & Chemical Corporation, Beijing 100728, China;
4. Sinopec Petroleum Exploration and Production Research Institute, Beijing 100083, China;
5. Sinopec Exploration Company, Sichuan Chengdu 610041, China;
6. Sinopec Research Institute of Petroleum Engineering, Beijing 100101, China;
7. School of Earth Resources, China University of Geosciences, Hubei Wuhan 430074, China;
8. School of Energy Resources, China University of Geosciences, Beijing 100083, China
Deep shale gas is the main alternative field for shale gas exploration and development in China. The deep shale gas in Wufeng Formation and Longmaxi Formation in Sichuan Basin and its periphery has a geological environment of high temperature, high pressure and high crustal stress. With the increase of deep overburden pressure, the reservoir porosity is reduced by 15%-20%, the permeability by 90%-95%, and the contribution of fractures in shale to permeability is decreased significantly. The deep gas content varies in different regions in Wufeng Formation and Longmaxi Formation, but generally varies little in the middle-shallow shale that has been exploited. The gas content is mainly controlled by the original sedimentary conditions and later preservation conditions. Deep shale underwent less structural uplift and erosion, and had good oil and gas preservation conditions. Deep shale formations are characterized by high temperature, large crustal stress, and high stress difference, which can easily lead to the enhanced shale plasticity, difficulties in fracture initiation and propagation, and high closure pressure in shale. For this reason, the proppant was cracked, thus influencing the propping degree of fracturing fractures; fracture conductivity decreases rapidly, and it is difficult to maintain the long-term conductivity. The biogenic siliceous shale in the WF2-LM4 graptolite zone is characterized by high quartz content and strong resistance to compaction, which are conducive to the formation and preservation of effective reservoirs. However, due to the large brittleness and rapid development of natural fractures, the lower limit of "sweet window" of the shale may exceed 5 km, which is the optimal interval for deep shale gas development. The enrichment degree of deep shale gas is mainly related to the superior congenital sedimentary and diagenetic conditions, burial and hydrocarbon generation and expulsion history, amplitude of later uplift, and differences in structural deformation. Shale gas can be fully exploited to successfully achieve the large-scale effective development of deep shale gas by optimizing the distribution areas of deep shale with high brittleness, high porosity and permeability, high pressure coefficient and high gas conten, establishing a suitable method of volume fracturing treatment in deep shale, and a reasonable production system through continuous optimization.
何治亮, 聂海宽, 胡东风, 蒋廷学, 王濡岳, 张钰莹, 张光荣, 卢志远. 深层页岩气有效开发中的地质问题——以四川盆地及其周缘五峰组—龙马溪组为例[J]. 石油学报, 2020, 41(4): 379-391.
He Zhiliang, Nie Haikuan, Hu Dongfeng, Jiang Tingxue, Wang Ruyue, Zhang Yuying, Zhang Guangrong, Lu Zhiyuan. Geological problems in the effective development of deep shale gas: a case study of Upper Ordovician Wufeng-Lower Silurian Longmaxi formations in Sichuan Basin and its periphery[J]. Acta Petrolei Sinica, 2020, 41(4): 379-391.
ZHANG Jinchuan,LI Yuxi,NIE Haikuan,et al.Geologic setting and drilling effect of the shale cored Well Yuye-1,Penshui County of Chongqing[J].Natural Gas Industry,2010,30(12):114-118.
DONG Dazhong,ZOU Caineng,YANG Hua,et al.Progress and prospects of shale gas exploration and development in China[J].Acta Petrolei Sinica,2012,33(S1):107-114.
WANG Zhigang.Reservoir formation conditions and key efficient exploration & development technologies for marine shale gas fields in Fuling area,South China[J].Acta Petrolei Sinica,2019,40(3):370-382.
Strategic Research Center of Oil and Gas Resources,Ministry of Land and Resources.Investigation and evaluation and selection of favorable areas of the potential of shale gas resources in China[M].Beijing:Science Press,2016.
[5]
HE Zhiliang,LI Shuangjian,NIE Haikuan,et al.The shale gas "sweet window":"the cracked and unbroken" state of shale and its depth range[J].Marine and Petroleum Geology,2019,101:334-342.
HE Zhiliang,HU Zongquan,NIE Haikuan,et al.Characterization of shale gas enrichment in the Wufeng-Longmaxi Formation in the Sichuan Basin and its evaluation of geological construction-transformation evolution sequence[J].Natural Gas Geoscience,2017,28(5):724-733.
JIANG Tingxue,ZHOU Jian,ZHANG Xu,et al.Overview and prospect of fracture propagation and conductivity characteristics in deep shale gas wells[J].Scientia Sinica Physica,Mechanica & Astronomica,2017,47(11):114603.
[8]
FAN Li,THOMPSON J W,ROBINSON J R.Understanding gas production mechanism and effectiveness of well stimulation in the Haynesville shale through reservoir simulation[R].SPE 136696,2010.
[9]
BAIHLY J D,ALTMAN R M,MALPANI R,et al.Shale gas production decline trend comparison over time and basins[R].SPE 135555,2010.
[10]
GENTZIS T.Review of the hydrocarbon potential of the Steele Shale and Niobrara Formation in Wyoming,USA:a major unconventional resource play?[J].International Journal of Coal Geology,2016,166:118-127.
CHEN Zuo,ZENG Yijin.Present situations and prospects of multi-stage fracturing technology for deep shale gas development[J].Petroleum Drilling Techniques,2016,44(1):6-11.
[12]
American Association of Petroleum Geologists,Energy Minerals Division.Unconventional energy resources:2017 review[J].Natural Resources Research,2018,28(4):1661-1751.
[13]
GENTZIS T.A review of the thermal maturity and hydrocarbon potential of the Mancos and Lewis shales in parts of New Mexico,USA[J].International Journal of Coal Geology,2013,113:64-75.
NIE Haikuan,TANG Xuan,BIAN Ruikang.Controlling factors for shale gas accumulation and prediction of potential development area in shale gas reservoir of South China[J].Acta Petrolei Sinica,2009,30(4):484-491.
MA Xinhua,XIE Jun.The progress and prospects of shale gas exploration and exploitation in Southern Sichuan Basin,NW China[J].Petroleum Exploration and Development,2018,45(1):161-169.
XIE Jun,ZHAO Shengxian,SHI Xuewen,et al.Main geological factors controlling high production of horizontal shale gas wells in the Sichuan Basin[J].Natural Gas Industry,2017,37(7):1-12.
CHEN Xu,FAN Junxuan,ZHANG Yuandong,et al.Subdivision and delineation of the Wufeng and Lungmachi black shales in the subsurface areas of the Yangtze platform[J].Journal of Stratigraphy,2015,39(4):351-358.
NIE Haikuan,WANG Hu,HE Zhiliang,et al.Formation mechanism,distribution and exploration prospect of normal pressure shale gas reservoir:a case study of Wufeng Formation-Longmaxi Formation in Sichuan Basin and its periphery[J].Acta Petrolei Sinica,2019,40(2):131-143.
JIN Zhijun,HU Zongquan,GAO Bo,et al.Controlling factors on the enrichment and high productivity of shale gas in the Wufeng-Longmaxi formations,Southeastern Sichuan Basin[J].Earth Science Frontiers,2016,23(1):1-10.
NIE Haikuan,JIN Zhijun,MA Xin,et al.Graptolites zone and sedimentary characteristics of Upper Ordovician Wufeng Formation-Lower Silurian Longmaxi Formation in Sichuan Basin and its adjacent areas[J].Acta Petrolei Sinica,2017,38(2):160-174.
[21]
HE Zhiliang,NIE Haikuan,ZHAO Jianhua,et al.Types and origin of nanoscale pores and fractures in Wufeng and Longmaxi shale in Sichuan Basin and its periphery[J].Journal of Nanoscience and Nanotechnology,2017,17(9):6626-6633.
[22]
NIE Haikuan,SUN Chuanxiang,LIU Guangxiang,et al.Dissolution pore types of the Wufeng Formation and the Longmaxi Formation in the Sichuan Basin,South China:implications for shale gas enrichment[J].Marine and Petroleum Geology,2019,101:243-251.
DONG Wenqiang.Effects of temperature and effective stress on stress sensitivity of shale reservoirs[J].Petrochemical Industry Application,2018,37(3):62-66.
HE Zhiliang,NIE Haikuan,ZHANG Yuying.The main factors of shale gas enrichment of Ordovician Wufeng Formation-Silurian Longmaxi Formation in the Sichuan Basin and its adjacent areas[J].Earth Science Frontiers,2016,23(2):8-17.
[25]
GUO Xusheng,HU Dongfeng,LI Yuping,et al.Geological factors controlling shale gas enrichment and high production in Fuling shale gas field[J].Petroleum Exploration and Development,2017,44(4):513-523.
[26]
HE Zhiliang,HU Zongquan,NIE Haikuan,et al.Characterization of shale gas enrichment in the Wufeng Formation-Longmaxi Formation in the Sichuan Basin of China and evaluation of its geological construction-transformation evolution sequence[J].Journal of Natural Gas Geoscience,2017,2(1):1-10.
FAN Cunhui,LI Hu,ZHONG Cheng,et al.Tectonic fracture stages and evolution model of Longmaxi Formation shale,Dingshan structure,Southeast Sichuan[J].Acta Petrolei Sinica,2018,39(4):379-390.
NIE Haikuan,ZHANG Jinchuan,MA Xiaobin,et al.A preliminary study of negative adsorption phenomena of shale adsorption gas content by isothermal adsorption[J].Earth Science Frontiers,2013,20(6):282-288.
JI Liming,WU Yuandong,HE Cong,et al.High-pressure hydrocarbon-generation simulation and pore evolution characteristics of organic-rich mudstone and shale[J].Acta Petrolei Sinica,2016,37(2):172-181.
YU Lingjie,FAN Ming,CHEN Hongyu,et al.Isothermal adsorption experiment of organic-rich shale under high temperature and pressure using gravimetric method[J].Acta Petrolei Sinica,2015,36(5):557-563.
LI Donghui,NIE Haikuan.A new method to calculate shale gas content based on gas reservoir characterization-a case study of Wells JY 1 and PY 1 in Sichuan Basin and its surrounding areas[J].Oil & Gas Geology,2019,40(6):1324-1332.
WANG Pengfei,JIANG Zhenxue,HAN Bo,et al.Reservoir geological parameters for efficient exploration and development of Lower Cambrian Niutitang Formation shale gas in South China[J].Acta Petrolei Sinica,2018,39(2):152-162.